MaterialsSchool Certificate Topic

Outcomes• a) identify that a new compound is

formed by rearranging atoms rather than by creating matter x

• b) classify compounds into groups based on common chemical characteristics

• c) construct word equations from observations and written descriptions of a range of chemical reactions

• d) identify a range of common compounds using their common names and chemical formulae

• e) qualitatively describe reactants and products in the following chemical reactions:

• i) combustion x• ii) corrosion• iii) precipitation x• iv) acids on metals and acids on carbonates• v) neutralisation• vi) decomposition x• f) describe the role of indicators. x

Spelling WordsReactantsProductsCombustionCorrosionPrecipitationCarbonateAcidalkali

• Neutralisation• Decomposition• Indicator• chemical• Formulae• Equation• Element• compound

Materials – An Introduction

For most of the nineteenth century, products were made out of naturally occurring materials. Billiard balls, for example, were made out of the ivory from elephant tusks.

In 1869, John Hyatt developed an alternative for ivory, called “celluloid”. This was the first commercially produced artificial plastic.

In 1884, Louis Bernigaut used the same substance to make shiny fibres/threads. This was called “rayon”. At the same time photographic film was also made using Hyatt’s celluloid.

In 1907, “Bakelite” was made. This is a mouldable plastic which can become hard and insoluble after heating. This was useful for moulded insulation, valves, pipes, knobs, buttons, knife handles and even billiard balls.

Questions• Outline the reasons why an

alternative was needed for using ivory.

• Start a timeline to show the development of plastics. Do you know how to do a proper timeline?(You can continue to complete this as we study plastics further.)

b) classify compounds into groups based on common chemical characteristics

• Renewable and Non renewable• Natural and Synthetic• Organic and Inorganic• Biodegradable and Non biodegradable• Commercially Viable• Minerals• Amorphous• Ionic• Molecular• Acids• bases

Elements and Compounds-revision

• Materials can be elements or compounds.• Sometimes materials need to be separated from

mixtures.• To Do:

– Recall the definitions for “element”, “compound”, and “mixture”.

– List all of the materials you can think of that are used today.

– How can you classify the materials used into two main groups? (Hint: Think back to ivory and plastic)

– Draw up a table classifying the materials the class has identified.

Metals and Non Metals• Elements can be divided into metals and

non metals. So, too, can materials used.• Compare the properties of metals and

non metals. (What is a “property” of something?)

• To Do: Draw up a table to show the similarities and differences between metals and non metals. This is the most effective way to answer a “Compare” question. Do you know how to draw up a proper table for your School Certificate?

Drawing up a Table.• A table should always have a Heading which is relevant to

what you want to show. Eg “Properties of Metals and Non Metals”

• There should be clear columns and rows. It is best to do this using ruled lines.

• Work out how many columns you need. Make sure that they will not be too confusing and shows the relationships clearly.

• How many rows do you need? Do not forget the row for the headings.

• Fill in the information. If it is not making sense/ getting too complicated, or you are repeating the same thing over and over (particularly units of measurement) work out how to simplify it and fix this.

• So … for the task you have to do… there can be many different ways to complete this task and get full marks in your examination. Have a go. Check with others in the class.

Properties of Metals and Non Metals

Property Metals Non MetalsMalleability Yes No

Ductility Yes No

Conductor of Electricity

Yes No (except Carbon)

Conductor of Heat Yes No

Density Very (atoms packed tightly)

Lower

States Existing In Solid, Liquid (Hg) Solid, Liquid and Gas

Electronegativity Low Higher

Metals as Materials• Pure Metals – eg. Gold, Copper, Aluminium. Not many can be

used in this form because they are usually too soft, expensive, reactive or will corrode. (What does this term mean?

• Alloys – a metal combined with one or more other elements. (forming a compound) The properties of the alloy made are different from the original base metal used. Eg. Brass – base metal is copper; Steel = iron +small amounts of carbon. The more carbon added, the stronger that type of steel will be (plus also more expensive)

• Native metals – metals that are in their natural state when mined. Eg gold, silver, platinum and copper. They are found this way because they are unreactive. (Think back to Year 9 Reactions topic)

• Ores – when the metal is found as a compound (in the minerals in rocks) and is economically viable to mine. eg – aluminium from bauxite (aluminium oxide). The ore needs to be extracted and then processed to separate the metal from the rock.

Copy this table down. Can you see any trends?

Copy this table into your book

d) identify a range of common compounds using their common names and chemical formulae

Metals In The CrustMetals make up only a quarter of the Earth’s crust. Oxygen and silicon make up the rest. Oxygen is by far the most abundant, being combined with metals as oxides or with silicon as silicon dioxide in sand or silicates

Skill: Now convert the pie chart into a table in your book.

Skill – Drawing up a Pie Chart• The diagram on the other slide showed a pie

chart. – What is a pie chart?– How can you draw one in a Science exam?

Pie charts are a mandatory skill for you to know for your School Certificate so lets make sure you can draw one properly.

Pie charts show relative percentages or proportions of a whole. In other words, it is showing the fraction that each factor makes up as a percentage of all that is available, or counted.

Drawing a Pie Chart• Use a compass to draw a circle. (Yes you will need to bring

one to your exams.)• How many degrees in a circle? Work out roughly (but as

accurately as possible) the fraction that each factor makes up in the pie. Do you need a hand with working out fractions? ASK NOW.

• Calculate the number of degrees this fraction is equal to. NEED A HAND?

• Using a protractor (yes you need one of these as well) work out where to draw each sector line, and draw these in, using a ruler.

• Now – this is the part most students forget – MAKE UP A KEY – showing each factor and the colour/pattern that indicates each one.

• Eg. = aluminium• Now colour each section .

– NOW DRAW THE PIE CHART FOR THE ABUNDANCE OF METALS IN THE EARTH’S CRUST, USING THE TABLE YOU MADE EARLIER.

Minerals Used in Everyday

Life

• How many household products are made of a single mineral? Which ones are combinations?

• About how many minerals are needed to make a computer? Why?

• What is the most prevalent mineral/material in items in an office? Are you surprised by it? Research this material and find out all of the products that it makes. What would happen if we run out of it?

• Where do most of the minerals found in a house come from?

• Think about all of the mining and drilling necessary to create these products we use every day. What does this indicate about the mining industry?

Minerals And Ores

• All other metals are found combined with other elements as compounds. Minerals are rocks containing large amounts of a particular metal. If there is sufficient metal to make it worth mining, it is called an ore. Mining produces valuable metals and creates jobs. Sometimes, however, mining is not worth its expense or the negative effects on society and the environment.

Mining for Minerals • Why does gold sink to the

bottom when miners "pan" for gold?

• Describe the tools and engineering challenges of making a shaft mine safe for mineral extraction by miners.

• How is gypsum transformed into building materials? Can you name other minerals that you have in your home that were recovered through mining?

• Are mined materials renewable or non-renewable resources?

Even though minerals are very useful as materials, the processes needed to recover them, and refine them present problems for the environment.

Mining for OresUnderground mines are used for

the mining of deep ores but water penetration, possible collapse, venting of poisonous and explosive gases and the provision of fresh air for the miners are problems that must be managed.

If the ore is close to the surface, open-cut mining is easier. An overburden of soil is removed and the ore is dredged out, creating benches, or steps that spiral into the hole. These are also used as access roads to haul the ore to the surface by truck. Open-cut mines cause problems including unsightliness, pollution of surrounding areas with dust, pooling of water, destruction of land above the ore, and the need to repair the land after mining ceases.

COMPARE open cut and

underground mining.

HINT: A table is usually the

clearest way to answer a

“Compare” question (show similarities and

differences)

The Mining Process

Before mining begins, we need to know:• How much ore is there and how concentrated is it?• How deep is the ore? What type of mine is needed?• Is the site close to existing ports and rail lines?• Which workers can be employed?• Who owns or controls the land? • What water and air pollution will it cause?• What

damage will be done to the environment • What is the cost of building the mine and the

processing plants, and repairing the environmental damage?

• What is the current and expected future price of the metal?

• What profit is expected?

Concentration Of The Ore

Impurities and waste called gangue are mined with the ore. The mined material is crushed by rollers or by large steel balls that fill a large rotating drum called a ball mill. Gravity and sieves separate some of the gangue, with the remainder then separated by froth-flotation. This is a technique pioneered in Broken Hill, in which the crushed ore floats away on a frothy emulsion of oil and water, leaving the gangue behind. The ore is now ready for extraction.

Separating Metals from their Ores Electrolysis

• Electrolysis uses a huge amount of electricity and is used only when there is no cheaper method available.

• A voltage is applied to a molten sample or solution of the ore and the positive metal ions move to the negative electrode. When it gets there, the ion is forced to take back its outer-shell electrons to form metal atoms that then plate the electrode. Sodium is extracted from rock salt by this method.

FIRST – Lets revise the structure of the atom, particularly shells and charges of particles. Do you remember how atoms gain an overall charge?

What does this look like?

A Diagram of Electrolysis for you to copy.

PRACTICAL Electrolysis

EXTENSIONCase Study of Electrolysis.

• Sodium (NaCl) is made by electrolysis of sea water or, rock salt. The salt is melted to break the salt crystals into its ions, then converted into pure elements by electrolysis.

• At the negative electrode:Na+ + e– -------- Na

• and at the positive electrode:2Cl– --------- Cl2 + 2e-

• Overall,2NaCl(l)---------- 2Na(l) + Cl2(g)

Separating Metals from their Ores Heat

• Heat is sometimes enough energy to extract the pure metal. This is called smelting.

• The more reactive metals such as lead, iron and zinc need carbon or carbon monoxide (CO) to help the conversion along.

• To extract iron, coke (a source of carbon), limestone (CaCO3) and iron ore (Fe2O3) are heated in a blast furnace.

What does this look like?

• Smelting of iron occurs as a series of chemical reactions. First the coke reacts to form carbon dioxide:

• First the coke reacts to form carbon dioxide:C(s) + O2(g)-------- CO2(g)

• Limestone then decomposes, forming calcium oxide and more carbon dioxide:CaCO3(s)--------- CaO(s) + CO2(g)

• Carbon dioxide reacts with more coke, forming carbon monoxide:CO2(g) + C(s)--------- 2CO(g)

• This reacts with the iron ore to form molten iron, which then runs to the bottom of the furnace:Fe2O3(s) + 3CO(g)--------- 2Fe(l) + 3CO2(g)

EXTENSIONCase Study of Heat

• Waste calcium oxide reacts with sand in the iron ore, forming calcium silicate:

• CaO(s) + SiO2(s)-------- CaSiO3(l)• Calcium silicate is called slag and floats on the

molten iron.• More stable metals only need roasting in air. Most

copper is extracted by roasting copper(I) sulphide, found in an ore called copper pyrites:

• Cu2S(s) + O2(g)-------- 2Cu(l) + SO2(g)

Case Studies in Materials• Copy this table into your book. You will use

one of these for each case study completed.

Material Composition S/L/G Positives Negatives Questions

Materials Used in

Medicine

Materials for Joint Replacement in Humans

• Generally, the most common materials used in orthopaedic implants are metals and a type of plastic called polyethylene.  These two material types are combined in most joint implants, that is, one component is made from metal, and one from polyethylene. When properly designed and implanted, the two components can rub together smoothly while minimizing wear. 

• While some pure metals have excellent characteristics for use as implants, most metal implants are made from a mixture of two or more metals. These mixed metals are called alloys. By combining metals, a new material can be created that has a good balance of the desired characteristics. The most common metal alloys used in orthopaedic implants are stainless steels, cobalt-chromium alloys, and titanium alloys.

Materials Used in Implants• Draw up a table to COMPARE the

materials used in surgical replacements.

• The headings should be –– Name of material– Type of material– Composition– Properties– Uses

Metals Used in ImplantsStainless Steel • Stainless steel is a very

strong alloy, and is often used in implants to help repair fractures, such as bone plates, bone screws, pins, and rods. 

• Stainless steel is made mostly of iron, with other metals such as chromium or molybdenum added to make it more resistant to corrosion.

• There are many different types of stainless steel. The stainless steels used in orthopaedic implants are designed to resist the normal chemicals found in the human body.

Cobalt-chromium Alloys

Cobalt-chromium alloys are also strong, hard, biocompatible, and corrosion resistant. These alloys are used in a variety of joint replacement implants, as well as some fracture repair implants, that require a long service life. While cobalt-chromium alloys contain mostly cobalt and chromium, they also include other metals, such as molybdenum, to increase their strength

Parts used in a hip replacement.

Titanium Alloys Titanium alloys are considered to be biocompatible.  They

are the most flexible of all orthopaedic alloys. They are also lighter weight than most other orthopaedic alloys.  Consisting mostly of titanium, they also contain varying degrees of other metals, such as aluminum and vanadium.

Titanium Pure titanium may also be used in some implants where high strength is not required. It is used, for example, to make fiber metal, which is a layer of metal fibers bonded to the surface of an implant to allow the bone to grow into the implant, or cement to flow into the implant, for a better grip.

Tantalum Tantalum is a pure metal with excellent physical and biological characteristics. It is flexible, corrosion resistant, and biocompatible

Problem with Using Metals #1-

The Activity Series• Experiment. Add a small piece of

magnesium to dilute hydrochloric acid. Note the reactivity. Repeat with iron and copper. Record your results in a table.

• Metals vary in their reactivity with other substances. Eg magnesium( ) reacted vigorously with dilute HCl, iron ( ) bubbled slowly and copper ( ) didn’t react at all.

PRACTICAL Activity Series of Metals

• Aim: to see which is the most reactive metal magnesium, iron or copper.

• Materials: 3 test tubes, test tube rack, small clean pieces of Mg, Fe and Cu, solutions of magnesium nitrate, iron nitrate and copper nitrate.

• Method:

• Add a small piece of Mg to 3 test tubes. Add

Results• Rule up a table to record your results.

Discussion questions.1. Which metal reacted with all of the solutions?

Write word equations to show these reactions.2. Which metal reacted with none of the solutions?3. Which is the most reactive metal? Least

reactive?ConclusionList the metals in order from most to least reactive.

Activity Series• Using large numbers of metals and

their solutions, chemists have come up with a list of metals from most to least reactive.

• This is done by studying the results of displacement reactions.

• A more reactive metal will displace a less active metal from solution.

• Sodium + copper nitrate → sodium nitrate + copper

• Some metals lose their electrons more easily than others. These metals are reactive and are harder to extract. Different extraction techniques are required, depending on the metal’s position in the activity series.

Look at this table – summarise the trends.

Activity Series – A Summary of TrendsAs we move up the activity series:

• the chance of metals reacting with chemicals becomes greater

• the metals become less stable• there is less chance of finding the metals in their

natural state• the compounds of the metals become more

stable and more difficult to break down• the extraction process becomes more difficult and

more expensive. Eg sodium needs to be extracted by electrolysis whereas lead is extrcted by smelting. Gold and silver are found as metals in nature as they are unreactive.

Processing of Materials to Make Implants for Surgical Procedures.

PlasticsPolyethylene

• Polyethylene is a type of plastic commonly used on the surface of one implant that is designed to contact another implant, as in a joint replacement.

• Polyethylene is also the material used to make milk cartons but he polyethylene used in orthopaedic implants is a much higher grade. In fact, a special type of medical-grade polyethylene was developed specifically for use in orthopaedic implants. 

• Polyethylene is very durable when it comes into contact with other materials. When a metal implant moves on a polyethylene surface, as it does in most joint replacements, the contact is very smooth and the amount of wear is minimal.   

• Patients who are younger or more active may benefit from polyethylene with even more resistance to wear. This can be accomplished through a process called crosslinking, which creates stronger bonds between the elements that make up the polyethylene. The appropriate amount of crosslinking depends on the type of implant. For example, the surface of a hip implant may require a different degree of crosslinking than the surface of a knee implant.

Ceramics Ceramic materials are usually made by pressing and heating metal oxides (typically aluminium oxide and zirconium oxide) until they become very hard. These ceramic materials are strong, resistant to wear, and biocompatible. They are used mostly to make implant surfaces that rub together but do not require flexibility, as in the surfaces of a hip joint.

Composites

• Composite materials are made by mixing two or more separate materials without creating a chemical bond between the materials. For example, carbon fibres may be added to another material to provide additional strength, but the two materials do not combine in a way that creates a new material. Metal alloys and ceramics are not considered to be composite materials because their ingredients are chemically bonded to create a new material. 

• On a larger scale, two layers of different materials can be

combined to create a composite material with the desired characteristics. The stem of a hip implant, for example, may consist of layers of two different materials that together provide the desired combination of strength and flexibility.

Materials Used in Building

Comparing Building Materials

Questions to Answer.

* Identify which material seems to break most easily in tension? In compression?

* Make a survey of all the materials around you in the room. List any signs of wear and tear, and which parts look as though they are about to come apart, break, or fail in some way?

* Go on a "materials" scavenger hunt where you live. Identify structures made out of the eight materials described in the materials lab? Why do you think each material was a good choice for that structure?

* What materials are used to build houses and apartment buildings where you live? Why do you think these materials were chosen?

* If you travelled to another location, do you think the buildings people live in would be made of different materials? Why or why not?

* Which materials would you choose to make 1) a bridge, 2) an office skyscraper, and 3) a dam wall? Give reasons for your choices.

Wood as a Material• Wood Pros+Cons

Strengths: Cheap, lightweight, moderately strong in compression and tensionWeaknesses: Rots, swells and burns easily

• Wood ApplicationsBridges, houses, two- to three-story buildings, roller coasters

• Wood is cheap and pretty strong in compression. That's why people build houses out of wood!

• It isn't easy to break a block of wood because wood is strong when it is pulled in the direction of its fibres. It would be three times easier to break a block if it was stretched from the top and bottom, across the direction of its fibres.

Plastic as a MaterialPlastic PropertiesType: High-strength plastic fabric Ingredients: Long chains of moleculesPros+ConsStrengths: Flexible, lightweight, long-lasting, strong in compression and tensionWeaknesses: ExpensiveApplicationsUmbrellas, inflatable roofs over sports arenasPlastic Compression Compared to steel, plastic can be squeezed easily, but it takes a lot of effort to make it break. The long chains of molecules that make up plastic can be pulled and pushed in many directions without failing.

• Plastic Tension Plastic can be stretched pretty far before it finally breaks. The long chains of molecules that make up plastic can be pulled in many directions without snapping. That's one of the reasons why circus tents are made of plastic fabric!

Practical – Packaging Materials

• Compare properties of styrofoam and rice based packaging material.

• See Steve Spangler site on TALE (DET intranet)

Aluminium as a Material

• PropertiesType: Aluminium alloy Ingredients: Aluminium with magnesium & copper

• Pros+ConsStrengths: Lightweight, doesn't rust, strong in compression and tensionWeaknesses: Expensive

• ApplicationsAirplane wings, boats, cars, skyscraper "skin"

• Compression It is pretty hard to break an aluminium block. That's because the magnesium and copper inside this block makes it almost as strong as steel!

• Tension It isn’t easy to break an aluminium block. That's because aluminium, when combined with metals like magnesium and copper, is almost as strong as steel!

Brick as a Material

PropertiesIngredients: Burned clayPros+ConsStrengths: Cheap, strong in compressionWeaknesses: Heavy, weak in tensionApplicationsWalls of early skyscrapers and tunnels, domesCompression It is very hard to make brick crumble. Bricks are very strong in compression. That's why early houses were made of brick!Tension A brick can be pulled apart easily! That's because bricks are very weak in tension.

Concrete as a Material

• PropertiesIngredients: Cement, water, small stones

• Pros+ConsStrengths: Cheap, fireproof and weatherproof, moulds to any shape, strong in compressionWeaknesses: Cracks with temperature changes, weak in tension

• ApplicationsEarly arch bridges and domes

• Compression Concrete has to be squeezed really hard to make it break. That's because concrete is very strong in compression.

• Tension It is possible to pull apart the small stones and cement in a concrete block easily. That's because concrete is weak in tension

Iron as a Material• Iron Properties

Type: Cast iron Ingredients: Iron with lots of carbon

• Iron Pros+ConsStrengths: Moulds to any shape, strong in compressionWeaknesses: Weaker than steel in tension, breaks without warning

• Iron ApplicationsArch bridges, cannons, historic domes

• Iron Compression It isn’t easy to squeeze a cast-iron block. Cast iron is strong in compression. That's why early arch bridges were made of cast iron.

• Iron Tension It is easy to pull a cast-iron block apart. That's because cast iron is brittle -- it snaps without warning.

Steel as a Material

• PropertiesType: High-strength steelIngredients: Iron with a touch of carbon

• Pros+ConsStrengths: One of strongest materials used in construction, strong in compression and tensionWeaknesses: Rusts, loses strength in extremely high temperatures

• ApplicationsCables in suspension bridges, trusses, beams and columns in skyscrapers, roller coasters

• Compression Steel has to be pushed extra hard to make it bend and break. Steel is stronger than any other material in compression. That's why engineers choose steel beams and columns to support most skyscrapers.

• Tension Steel has to be pulled incredibly hard to make it break because steel is stronger than any other material in tension. That's why the cables in the Golden Gate Bridge are made of steel.

Comparing Different Types of Steel

• This interactive activity and illustrated text offers an in-depth explanation of steel and other alloys and how they've affected modern technology. An interactive table displays the contents and characteristics of seven elements that are commonly used in the production of steel alloys. Two text essays detail iron and steel production and why the non-corrosive, rust-resistant, and lightweight properties of stainless steel have revolutionized industries from medicine to transportation.

Questions to Answer

1. Identify four different materials that contain iron? 2. Identify the main strengthening element in steel? 3. Contrast steel and iron? 4. Compare steel and stainless steel 5. Identify the element that gives stainless steel its shiny surface? 6. List some advantages of stainless steel? 7. Discuss, using examples, how stainless steel has impacted technology?

Problem with Using Metals #2 - Corrosion

• For rusting of iron to take place, both oxygen and water must be present as either liquid or vapour. The rusting process can be accelerated by salts or heat.

• The rusting reaction is basically Iron + Oxygen - Iron Oxide

This is an oxidation reaction

PRACTICAL Corrosion of Metals

How Has Science Helped to Overcome This Problem?

Corrosion Protection – New Materials Are Made.

Galvanising• Another method is to coat the surface or attach another

more reactive metal. • Galvanised iron is iron dipped in molten zinc. • Zinc is more reactive than iron and will react instead of

it. This is called sacrificial protection. • Scratches and chips will not rust, as long as some zinc

is close by. • Nails and roofing materials are commonly made from

galvanised iron. Reactive magnesium blocks are often bolted onto steel structures such as piers and deepwater gas rigs and oil rigs at sea. The magnesium sacrifices itself to protect the structure.

Materials of the Future

The ability to improve on current materials, or develop new materials in the future, depends on understanding what makes materials different from one another…

Assessing Materials -

Making a Bike Helmet

QUESTIONS TO ANSWERBubble wrap and egg cartons are two of the materials used to solve the problem of protecting the water balloons.

1. Describe the properties of each material that make it a good choice.

2. Outline any downsides to using either one?

3. Propose other materials would you use? Justify your selection?

EXTRATake a look at some bike helmets.

• Assess the materials that make up a bike helmet.

• List other criteria you think designers need to take into consideration?

Making a Bike Helmet• Bubble wrap and egg cartons are two of the

materials used to solve the problem of protecting the water balloons. Describe the properties of each material that make it a good choice. Are there any downsides to using either one? What other materials would you use? Why?

• Did you notice how the water balloons came to a complete stop very suddenly when they hit the wall and then the floor? How did the homemade helmets protect the balloons at the moment of impact?

• Take a look at some bike helmets. In addition to the materials that make up a bike helmet, what other criteria do you think designers take into consideration?

• Structure-Property Relationships Revision• PART I VOCABULARY• For questions 1-9, use the word bank below. All words will be used one time.• condensation• deposition• evaporation• freeze• gas• liquid• melt• solid• sublimation• 1. The phase change from gas to liquid is called ____________________________.• 2. Ice is the ________________ phase of water.• 3. This phase of water is invisible. __________________________• 4. ______________________ occurs when energy is added to liquid water.• 5. Frost is an example of ______________________________.• 6. Ice will ___________________ when energy is added to it.• 7. The phase change from solid directly to gas is called ______________________.• 8. When liquid water loses energy it will __________________________.• 9. When water vapor cools it turn into a ___________________________.

• 10. Describe the arrangement of the water molecules in their solid form.• __________________________________________________________________• __________________________________________________________________• 11. What happens to the arrangement of the molecules in ice when energy is added?• __________________________________________________________________• __________________________________________________________________• 12. What physical changes occur when ice melts?• __________________________________________________________________• __________________________________________________________________• 13. What causes the physical changes in water when it melts?• __________________________________________________________________• __________________________________________________________________• 14. Describe the arrangement of the water molecules when liquid water evaporates.• __________________________________________________________________• __________________________________________________________________• 15. What physical changes occur to water as it vaporizes?• __________________________________________________________________• __________________________________________________________________

Labelling a Diagram

Why Do Materials Have Different Properties?

"So if the same molecules are in the solid, liquid, and vapour forms of water, why are their properties so different?" The properties of a material are affected not just by the kinds of atom in it, but also by how they are arranged, and how free they are to move around. There are different forms of carbon, from graphite to buckyballs.

Carbon New 'smart'

materials for the brain

• December 21st, 2008 in Nanotechnology / Materials Research done by scientists in Italy and Switzerland has shown that carbon nanotubes may be the ideal "smart" brain material. Their results, published December 21 in the advance online edition of the journal Nature Nanotechnology, are a promising step forward in the search to find ways to "bypass" faulty brain wiring.

Scanning electron microscope image of a metal electrode (dark region in centre of image) coated with carbon nanotubes

The research shows that carbon nanotubes, which, like neurons, are highly electrically conductive, form extremely tight contacts with neuronal cell membranes. Unlike the metal electrodes that are currently used in research and clinical applications, the nanotubes can create shortcuts between the two compartments of the neuron, resulting in enhanced neuronal excitability.

What is a “nanotube”

* Tiny tubes about 10,000 times thinner than a human hair

* Made of rolled up sheets of carbon hexagons.

* Discovered in 1991 by researchers at NEC* Have the potential for use as minuscule wires or in ultra small electronic devices. * To build these devices, scientists need to be able to manipulate the Nanotubes in a controlled way. * IBM researchers using an atomic force microscope (AFM), an instrument whose tip can apply accurately measured forces to atoms and molecules, have recently devised a means of changing a nanotube's position, shape and orientation, as well as cutting it

Eg 2. Carbon – Graphite/ diamonds/buckyballs.

• Chemical Formula: C In the the mid-16th century, a violent storm knocked over several trees in Borrowdale, England, uncovering a large deposit of a black substance that was first thought to be lead. More than 200 years later, an English scientist discovered that the substance was not actually lead, but a type of carbon instead. The substance was named graphite, after the Greek word meaning "to write," since that is how people used the substance. Graphite is a black silver with a metallic to dull luster. It has a hexagonal crystal system with crystals that are opaque. Due to its high temperature stability and chemical inertness graphite is a good candidate for a refractory material. It is used in the production of refractory bricks and in the production of Mag-carbon refractory bricks. Amorphous graphite is used in metallurgy, pencil production, and paint production.

What is Amorphous?• Define the word “amorphous”.1. Try to separate the word out into

syllables – a – morph – ous. What could each syllable mean? (This can help in an exam when you cannot use a dictionary.

2. Use a dictionary to check how close you were.

3. Write down the meaning in your own words.

Carbon - Diamond

Chemical Formula: C Diamonds were first mined over 4,000 years ago in India. During this period, however, diamonds were of no use as jewellery. Louis de Berqueur, was the first who discovered how to cut facets of a diamond, changing the world of fine jewellery. The diamond is not only found in India but also in South Africa, Brazil, Russia, Austria, and Arkansas. A diamond can be used for several things. The most obvious includes a gemstone for jewellery purposes. It is also used for various industrial functions, such as cutting, grinding, and polishing. These characteristics make the diamond "a girl's best friend."

Diamond's tight crystalline structure slows down light like no other known colourless substance. Diamond is crammed with electrons - no substance you have ever seen has atoms more densely packed - so light pokes along at less than 80,000 miles per second. That's more than 100,000 miles per second slower than in air.

How does the chemical structure of diamond give it these unique properties?

Why do Diamonds Sparkle?• Light enters a faceted gemstone

from all sides, but it may bounce back and forth several times inside before it finds a clean, straight shot out. All this changing direction accomplishes something very dramatic, because so-called white light actually contains all of the rainbow's colours. Each colour - red, orange, yellow, green, blue, and violet - bends and reflects inside the diamond slightly differently. The farther the light travels, the more the colours separate, or "disperse." Bounce light inside a diamond just two or three times and the colours disperse spectacularly. Diamond-like substitutes, including "cubic zirconia," a crystalline compound synthesized from the elements zirconium and oxygen, attempt to mimic this light-dispersing property, though they fall short of diamond's brilliance and unrivalled hardness.

NOTE: Do you remember Reflection and Refraction from Year 9? Maybe it is time to revise this.

Diamond Questions• Explain what happens to the speed

of light when it travels through a diamond.

• Account for the sparkle of diamonds?

• Propose what you think happens to the energy lost as light slows down?

• Explain why diamonds are so hard?

Carbon – “Bucky Balls”

• Buckminsterfullerene is a spherical shaped allotrope of carbon discovered in 1985.

• Chemical Formula: C60

• Three professors are credited with the discovery of fullerenes, a family of symmetrical carbon-cage molecules. Buckyball is the the most abundant and well-known carbon-cage molecule consisting of 60 carbon atoms. This huge molecule is being studied by many scientists for its ability to serve as a conductor, insulator, semiconductor, and superconductor.

Contrast the terms amorphous and allotrope?

• CONTRAST = Show the differences

• Now answer the question in your book.

Eg3. Carbonates – Another way to use Carbon as a material.

• Carbonates are widely used as pharmaceuticals, detergent, and pesticides.

• Chemical Formula of the carbonate ion: CO3 2-

• Carbonates were studied extensively by geologists. Common carbonates are barium carbonate, calcium carbonate, lead carbonate, and strontium carbonate. Carbonate is the salt of carbonic acid. Calcium carbonate is a brittle white rock, used in many buildings. Lithium carbonate is used to treat manic phases for bipolar disorder/manic depression. Carbonic acid is found in carbonated beverages, giving them a tart flavour.

Revision• Elements-are pure substances which

contain only one type of atom. Eg helium, oxygen, gold.

• Diags.

• Compounds are pure substances which contain 2 or more different types of atoms bonded together in fixed proportions. Eh water, methane, sodium chloride.

• Diags.

More complicated compounds

• Are made by reacting acids with different types of substances.

• These compounds are called salts.• Salts are named after the acid which

makes them.

What are carbonates?• Salts which react with acids to form a new salt,

carbon dioxide and water.• Carbonate + acid → salt + carbon dioxide + water

Naming salts• Salts are

named after the acid which they are made of.

acid formula Salt name ending

Hydrochloric HCl _ chloride

Sulfuric H2SO4 _ sulfate

nitric HNO3 _nitrate

phosphoric H3PO4_phosphate

Some Reactions which make salts

• Acid + alkali → salt + water• Acid + reactive metal → salt +

hydrogen• acid + carbonate → salt + carbon dioxide +

water

Exercises.• Complete these equations.• Acid + carbonate →

• Sodium carbonate + hydrochloric acid →• Calcium carbonate + hydrochloric acid →• Magnesium carbonate + sulfuric acid →• Lithium carbonate + sulfuric acid →• Potassium carbonate + nitric acid →• Aluminium carbonate + nitric acid →

Set 2• Acid + alkali →

• Sodium hydroxide + hydrochloric acid →• Magnesium hydroxide + hydrochloric acid →• Calcium hydroxide + sulfuric acid →• Ammonium hydroxide + sulfuric acid →• Sodium hydroxide + nitric acid →• Lithium hydroxide + nitric acid →

• A lot of alkalis are called ____________ .

Answers to Set 2• Acid + alkali → salt + water

• Sodium hydroxide + hydrochloric acid →sodium chloride + water• Magnesium hydroxide + hydrochloric acid →magnesium chloride

+ water• Calcium hydroxide + sulfuric acid →calcium sulfate + water• Ammonium hydroxide + sulfuric acid → ammonium sulfate +

water • Sodium hydroxide + nitric acid → sodium nitrate + water• Lithium hydroxide + nitric acid → lithium nitrate + water

• A lot of alkalis are called hydroxides .

Set 3. • Acid + reactive metal →• Sodium+ hydrochloric acid → • Calcium + hydrochloric acid → • Zinc + sulfuric acid →• Gold + sulfuric acid →• Iron + nitric acid →• Potassium + nitric acid →

Answers to Set 3. • Acid + reactive metal → salt +

hydrogen• Sodium+ hydrochloric acid → sodium chloride +

water• Calcium + hydrochloric acid →calcium chloride +

water• Zinc + sulfuric acid →zinc sulfate + water• Gold + sulfuric acid →no reaction• Iron + nitric acid →iron nitrate + water• Potassium + nitric acid →potassium nitrate +

water

the arrangement of atoms in a material

determines the properties. Eg

diamond and graphite are both made of

carbon atoms, buy they are arranged

differently.

What determines the properties of materials?

Testing Properties of Materials

• Dr. Chris Muhlstein explains that researchers learn about the scientific basis for failure of materials by running experiments in the lab, using a simple shape like a glass rod to calculate the strength of material and predict its failure. The same tests can be done at the micro and nano scale using tiny specimens.

Practical – Testing Materials• Materials such as metals (aluminium, iron,

copper, etc.), ceramics (silicon carbide, porcelain) or polymers (milk jugs made of polyethylene) are tested by scientists and engineers to reveal certain mechanical properties such as the maximum stress a material can withstand. The stress at which a material breaks is a measure of its strength. In this lesson you will be testing the strength of a delicious material you know as chocolate!

Write the heading for this practical in your book.

Aims of this experiment• Students will determine the amount of

stress required to break various candy bars.

• Students will examine how a various substances break and infer a cause for the type of break.

• Students will relate the candy bar experiment to the importance of nanotech laboratory work and how it is commercially and economically beneficial.Write an aim for this experiment. Which one above

is relevant?

• Predict the required stress to break each candy bar.

• Compare the amount of stress required to break various chocolate bars.

• Account for the differences in amounts of stress needed.

PFA: How Has Science Helped Society?

• Fracture surfaces can reveal how and why a material has failed. An image of a fracture surface has features or shapes that we can use to understand where a material failed and why. Scientists use an optical microscope or a scanning electron microscope to read a fracture surface at high magnifications, much like we read maps to find our way.

Research Task• ASSESS the materials used in ONE of

the following – Pacemakers– Cochlear implants– A really good website is this one:http://www.chilli.net.au/~science/links_science.htmGo to 9.3 medical technology-bionics.

How to Answer This Question

• Assess – Make a judgement of value, quality, outcomes,

results or size

1. State the issue/topic

2. What criteria (features) would you be looking at to decide the value of the material?

3. What are the positives for the material used? Remember to match these with the criteria.

4. What are the negatives for the material used?

5. Now weigh up the positives and negatives of the material - refer back to your criteria that you set. Make a brief statement which answers the question.

Do not be emotive – Stick to the facts.

Do not be too general – have facts.

Make sure that what you have written makes sense and uses key science words.

Glossary• biodegradable. Able to be broken down into simpler substances by the

activities of living organisms • composting. Breaking down plant and animal material using

microorganisms. For successful composting there must be sufficient water and air to allow the microoganisms to break down the material.

• decomposer organism. An organism, usually a bacterium or a fungus, that breaks down organic material into simple chemical components, thereby returning nutrients to the physical environment.

• greenhouse gas. A gas that is transparent to incoming solar radiation and absorbs some of the longer wavelength infrared radiation (heat) that the Earth radiates back. The result is that some of the heat given off by the planet accumulates, making the surface and the lower atmosphere warmer.

• monomer. A molecule that can join with other molecules to form a large molecule called a polymer. A monomer is the smallest repeating unit in a polymer chain.

• photosynthesis. The process in which green plants (and some microorganisms) use energy from light to make carbohydrates from carbon dioxide and water.

• polymer. Polymers are large molecules that are made up of many units (monomers) linked together in a chain. There are naturally occurring polymers (eg, starch and DNA) and synthetic polymers (eg, nylon and silicone).