Matter and AtomsMatter and Atoms

Chapter 2Chapter 2((Page 36Page 36))

Essential QuestionEssential Question

How does kinetic energy determine the How does kinetic energy determine the phases and physical properties of matter?phases and physical properties of matter?

Vocabulary: section 1Vocabulary: section 1

SubstanceSubstance MixtureMixture Physical propertyPhysical property Physical changePhysical change Chemical propertyChemical property Chemical changeChemical change Chemical reactionChemical reaction ScaleScale MicroscopicMicroscopic macroscopicmacroscopic

ElementElement Periodic tablePeriodic table Element symbolElement symbol Atomic numberAtomic number PeriodPeriod GroupGroup Atomic mass unitAtomic mass unit Avogadro's numberAvogadro's number

The “stuff” that we are made of is called matter.

Chemistry tells us how one kind of matter can be changed into a completely different kind of matter.

What are things made of?

Everything in the world is made up of Everything in the world is made up of small particles called atomssmall particles called atoms

Atoms are the smallest form of matterAtoms are the smallest form of matterThe atoms that are in your body are the The atoms that are in your body are the

same as the atoms that are in rocks, same as the atoms that are in rocks, water, plastic and metalswater, plastic and metals

Your body, plastic and wood all have high Your body, plastic and wood all have high amounts of carbon amounts of carbon

Chemistry is the study of matter, how it is Chemistry is the study of matter, how it is formed, and how one type of matter can formed, and how one type of matter can become another type of matterbecome another type of matter

There are over 1 million different types of There are over 1 million different types of matter around the classroommatter around the classroom

Scientists use different techniques to find Scientists use different techniques to find out if things (substances) are pure or out if things (substances) are pure or mixturesmixtures

A substance is matter that cannot be A substance is matter that cannot be separated into different kinds of matter by separated into different kinds of matter by physical means such as sorting, filtering, physical means such as sorting, filtering, drying, dissolving, heating or coolingdrying, dissolving, heating or cooling

Corn oil is a pure substance and salad Corn oil is a pure substance and salad dressing is notdressing is not

What are things made of?

How many different kinds of substances can you identify?

Is “pure orange juice” a pure substance?

“Pure orange juice”

• Water• Flavoring chemicals• Citric acid• Sugars• Fruit pulp• …

Orange juice may say pure on the Orange juice may say pure on the container, but it is actually made up of container, but it is actually made up of many different things (so it is a mixture)many different things (so it is a mixture)

Orange juice can be separated into water, Orange juice can be separated into water, different flavoring chemicals, citric acid, different flavoring chemicals, citric acid, sugars and fruit pulpsugars and fruit pulp

A mixture is anything that contains more A mixture is anything that contains more than one substancethan one substance

Wood is also a mixture because it is made Wood is also a mixture because it is made up of water, tannic acid, lignin and other up of water, tannic acid, lignin and other chemicalschemicals

mixture: matter that contains more than one substance. substance: a kind of matter that can’t be separated into other substances by physical means such as heating, cooling, filtering, drying, sorting, or dissolving.

Corn oil is a pure

substance

Oil and vinegar dressing is

a mixture of substances

Physical properties are properties that can Physical properties are properties that can be measured using the 5 sensesbe measured using the 5 senses

Color, density, malleability (able to be Color, density, malleability (able to be beaten into sheets), brittle, solid, liquid, or beaten into sheets), brittle, solid, liquid, or gas, hard, soft, wet, dry are all physical gas, hard, soft, wet, dry are all physical propertiesproperties

Physical changes are changes in state: Physical changes are changes in state: from solid to liquid to gasfrom solid to liquid to gas

Look at your desk – What is it made of?

wood, metal…

Can you think of a few physical properties?

is it heavy?

is it bendable?

does it feel cold?

can you scratch it?

…

Physical changes include changes in shape, phase or temperature.

Chemical properties – can only be observed when one Chemical properties – can only be observed when one substance changes into a different one ( such as substance changes into a different one ( such as rusting)rusting)

Chemical change – any change that transforms one Chemical change – any change that transforms one substance into a different one (and are hard to reverse)substance into a different one (and are hard to reverse)

Chemical changes are created by chemical reactionsChemical changes are created by chemical reactions Chemical reaction – any process that changes a Chemical reaction – any process that changes a

substance into a different onesubstance into a different one Examples of chemical reactions include turning cloudy, Examples of chemical reactions include turning cloudy,

temperature change, bubbling, and color changetemperature change, bubbling, and color change

Chemical properties are observed when a substance changes into a different substance.

Iron RustChemical change

Signs that a

chemical change has occurred

Scales are used by scientists to measure samples and to find out specific information

A meter scale measures things that are large (length of a car), a centimeter measures things that are small (the length of a book), and a millimeter measures things that are microscopic or really small (like the thickness of a fingernail, or a penny)

The universe can be understood using different scales for different types of data needed

Macroscopic scales measures things as small as tiny bacteria to things as large as planets

Microscopic scales measures things that are really small 10-9 or smaller

Assignment

Take a new sheet of paper and fold it into three sections

Write your name, the title of the chapter and the number

On the first section from the sheet of paper, please write six things that you learned from your notes so far that could appear on your test.

All matter in the world is made up of atomsAtoms make up everything that you can

taste, smell, see and touchA single grain of sand contains over 200

million million atomsA single grain of sand is 10-10 meters in

diameter so it would take 10, 000, 000, 000 atoms side by side to measure one meter in length

Sand has a mineral called feldspar in it that is a substance

Feldspar contains the elements oxygen, silicon and potassium

Elements are the smallest forms of matter that have similar characteristics

Elements can also be called specialized atoms, or atoms with unique characteristics

Oxygen atoms look, act and react differently to silicon atoms

How would you organize all those elements?

The periodic table is a special table designed to show all 118 atoms, where they are located and what other atoms they are similar to

The periodic table arranges elements according to how they combine with other elements (chemical properties) out of the 118 elements, only 88 – 92 atoms occur naturally

Most of the periodic table is made up of metals (on the left and in the middle), and the nonmetals are found on the right

Metals are shiny solids at room temperature (except mercury), conduct heat and electricity, and are malleable (beaten into sheets) and ductile (can be made into wires)

Non metals are poor conductors of heat and electricity and they are brittle (break easily)

Only one nonmetal bromine is a liquid at room temperature

The periodic table

Increasing atomic number

Incr

easi

ng a

tom

ic n

umbe

r

HydrogenLightest elementAtomic number: 1

UraniumHeaviest naturally occurring elementAtomic number: 92

Increasing atomic number

Incr

easi

ng a

tom

ic n

umbe

r

Each element on the periodic table has an atomic number that identifies it and makes it different from all other elements

The atomic number is the number of protons an element has (positive in charge)

The number of protons also is the same as the number of electrons an element has (negative in charge)

Atoms of each element are neutral in charge since the positives and negatives cancel out

Elements in the periodic table are arranged from the lightest to the heaviest (in progressive order)

The periodic table of elements was put together by early scientist who saw similarities between certain elements

For example, lithium, sodium, and potassium reacted with oxygen in ratios of two metals for each oxygen

The rows (from left to right) shows elements as they increase in the number of protons (atomic number)

The columns shows all the elements with the most similar characteristics such as reactivity and number of electrons in the outer shells

The periodic table organizes elements according to how they combine with

other elements (based on their chemical properties).

Assignment

On the same sheet of paper, (in the second section), please write six more things that you learned from your notes so far that could appear on your test.

Each element in the periodic table has its own box that identifies it with special features

Each box has an upper case letter then one or two lower case letter which identifies it (called the symbol)

Each box also has a small number called the atomic number (the number of protons the element has)

Each box also has a larger number called the atomic mass (equal to the number of protons and neutrons combined)

Neutrons are sub atomic particles like protons and electrons that are found in the nucleus with the protons

Each row in the periodic table is called a period and each column is called a group or family

Elements that belong to the same group (column) have

similar chemical properties.

Reminder

1 atomic mass unit (amu) = 1.66 x 10-24 g

Period 1 has only 2 elementsPeriod 2 has 8 elementsPeriod 3 has 8 elementsPeriod 4 has 18 elementsPeriod 5 has 18 elementsPeriod 6 has 32 elementsPeriod 7 has 32 elements

An element is so small that you need a small unit just to measure them

Atomic mass unit (amu) is 1.66 x 10-24 g The atom carbon has a weight of 12 amu Hydrogen has a weight of 1 amu The large number in each square of the periodic

table is an element’s average weight in amu The atomic mass has two important

interpretations: 1. the mass of a single atom in amu, 2. the mass of one mole of atoms in grams

We cannot measure amu easily so we use larger units called grams. So, when you see the atomic mass of carbon (12 amu) we use 12 grams to represent one mole of carbon, 1 amu of hydrogen is 1 gram and 16 amu of oxygen represents 16 grams which all equal one mole of carbon, hydrogen and oxygen respectively

In one mole of every substance is a very large number 6.022 x 1023 which is called Avogadro’s number

Scientist know that amu are too small to work with daily so they work with moles of atoms

A mole of atoms is the same as the atom, or elements atomic weight (in grams)

There are two types of problems used to calculate answers:Moles to mass of substanceMass in grams to number of moles of sample

One mole contains 6.02 x 1023 atoms

Avogadro’s number

How many moles are in 100 g of sulfur (S)?

Asked: The number of moles

Given: The element is sulfur and there are 100 g

Relationships: One mole of sulfur has a mass of 32.065 g

How many grams of calcium (Ca) do you need to have 2.50 moles of calcium?

Asked: The number of grams

Given: The element is calcium and there are 2.50 moles

Relationships: One mole of calcium has a mass of 40.078 g

Class Assignment

Write a one three dollar summary of what you learned in this section (be very specific and be very thorough).

Turn to page 66 and answer questions 1 – 11 then turn in the assignment.

Honors Chemistry Homework:

page 67 # 30 - 40

Vocabulary: section 2Vocabulary: section 2

MoleculeMolecule CompoundCompound Chemical formulaChemical formula Ball and stick modelBall and stick model Structural diagramStructural diagram Space filling modelSpace filling model Molecular surfaceMolecular surface Ionic compoundIonic compound ionion

Formula massFormula mass

If you cut a piece of

wax, is it still wax?

If you cut that smaller

piece again, is it still

wax?

When does it stop

being wax?

A bowl of wax can be broken down over and over until it cannot be broken down anymore without loosing its properties and you would have a molecule of wax

A single molecule is the smallest particle a substance can be

A molecule is two or more atoms bonded together

Wax is a compound made up of carbon and hydrogen

Pure elements are hard to find in nature

molecule: a group of atoms chemically bonded together.

compound: a substance containing more than one element in which atoms of different elements are chemically bonded together.

One H2O moleculeOne H2 moleculeOne O2 molecule

Most elements are so reactive that they are hardly found pure in nature

Gold is an element that can be found pure in nature

Hydrogen and oxygen easily form water instead of being in their pure form

Salt is also a compound of sodium and chlorine Pure sugar is also a compound made up of

carbon hydrogen and oxygen

Compounds and mixtures are different Mixtures are not combined chemically When compounds are made the elements that

make them up give up their individual properties and the compound has new properties

A compound is a molecule with two or more different atoms combined chemically

Soda is a mixture of sugar, water and carbon dioxide (not chemically bonded)

There are only 26 letters of the alphabet and yet there are tens of thousands of words in a dictionary

There are 92 naturally occurring elements and so there are trillions of compounds possible

Paraffin is made up of 21 carbon and 44 hydrogen atoms in a long chain

Aspirin is made up of 9 carbon, 4 oxygen and 8 hydrogen

What do all these have in common?

They are made up of only 3 types of atoms:

carbon, oxygen and hydrogen.

The properties of a compound depend more on

the exact structure of the molecule

than on the individual elements from which it is made.

Assignment

On the same sheet of paper, (in the third section), please write six more things that you learned from your notes so far that could appear on your test.

Many things that we use daily are made of plastics (man made polymers)

Polymers are repeating chains of molecules

Polyethylene is a polymer used to make bags, bottles, toys and other daily items

Rayon was the first artificial silk produced and was made of cellulose polymers

Chemical formulas are the way that scientist use to identify compounds

Chemical formulas tell the compounds needed and how many of each are required to make the compound correctly

H2O tells you that to make water you need two hydrogen and one oxygen (the 2 is called a subscript)

Compounds contain different ratios of elements

The properties of compounds depends on the structure of its molecules more than the individual elements that make them

For example, aspirin fights swelling and pain, but if any of the carbons or hydrogen are removed, the structure changes and the properties are no longer there

The same 21 atoms in aspirin can be rearranged to make other compounds that are not useful to us in daily life (acetyl benzoyl peroxide,

To completely describe a real molecule you must know its composition as well as its structure

Knowing the composition is not enough since there are a number of ways that the molecules can be arranged

There are 5 ways that a compound can be represented: chemical formula, structural diagrams, ball and stick model, space filling model, and molecular surface

Assignment

On the same sheet of paper, (on the back side of the paper), please write six more things that you learned from your notes so far that could appear on your test.

Structural diagram shows bonds, connections between atoms in the molecule

Ball and stick model gives you the three dimensional with angels

Space-filling model shows how close the atoms really are and how they overlap in each other’s space

Molecular surface model combines the ball and stick model to give transparent view of the molecule

Chemical Bonds and Electrons

A chemical bond forms when atoms transfer or share electrons.

A covalent bond is formed when atoms share electrons.

Types of Bonds Ionic bond- a chemical bond resulting from

electrostatic attraction between positive and negative ions (between a metal and non metal)

pure ionic bond - electrons are transferred. Ionic compounds cannot form molecules

because each atom has a chemical bond with the atom next to it as well as an associated bond with the elements around it

An ion is a charged atom with a positive (metal) or negative (nonmetal) charge

Types of Bonds

Covalent bond- a chemical bond resulting from the sharing of electrons between two atoms (between two nonmetals)

Formula mass

The sum of the atomic mass values of the atoms in a chemical formula is called the formula mass.

Assignment

On a blank sheet of paper, (in the second section of the back side), please write six things that you learned from your notes so far that could appear on your test.

Moles and Avogadro’s Number A mole is equal to an elements atoms mass (the

big number in the square of the elements periodic box)

A mole is also equal to the sum of all the elements in a molecule or a compound

Avogadro’s number is 6.022 X 1023 atoms This number represents the number of atoms

that can be counted in one mole of a substance Even though the masses will change from atom

to atom, the amount of atoms will always be the same in one mole 6.022 X 1023

Sample Questions

What is the mass of 1 mole of methane with the chemical formula CH4?

How many moles are in 100 grams of water?

How many moles are in 25 g of copper oxide (CuO)?

Questions Cont.

How many grams are in 2.3 moles of butane (C4H10)?

How many moles are in 30g of baking soda (NaHCO3)?

AssignmentWrite a three dollar summary of what you

learned in this section (be very specific and be very thorough.

Turn to page 66 and answer questions 12 – 18 then turn in the assignment.

Honors Chemistry Homework:

page 67 # 42 - 46

Vocabulary: section 3Vocabulary: section 3

Homogeneous mixtureHomogeneous mixture Heterogeneous mixtureHeterogeneous mixture SolutionSolution SolventSolvent SoluteSolute DissolvedDissolved ConcentrationConcentration dilutedilute

ConcentratedConcentrated SolubilitySolubility InsolubleInsoluble MolarityMolarity Molar volumeMolar volume Dalton’s law of partial Dalton’s law of partial

pressurespressures

A recipe calls for you to “mix until homogeneous.”

What does that mean?

A mixture that is uniform throughout. Different samples may have different compositions.

Most matter is made up of many different compounds

A homogeneous mixture is where all parts of the mixture are uniformly mixed (a sample taken from the top is the same as a sample taken from the bottom)

Brass is made up of 70 % copper and 30 % zinc (if you take a sample of brass from different locations they would be the same percentage throughout)

A heterogeneous solution is one where samples taken would have different concentrations of what makes them (example Italian dressing or concrete)

Now you have four types of matter Homogeneous mixture – more than one type of

matter mixed together uniformly Heterogeneous mixture – more than one type of

matter mixed differently throughout Element – a substance containing only one type of

atom Compound – a substance containing more than one

type of atom chemically bonded together

A solution – a mixture that is homogeneous A solvent – a substance that makes up the

biggest percentage of the mixture (usually a liquid)

Solutes – any substance in a solution other than the solvent

Dissolved – when molecules of a solute are completely separated from each other and dispersed into a solution

What happens when sugar is added to water?

A solution is obtained.

Concentration of a solution describes how much of each solute there is compared to the total solution

A solution is said to be dilute when there is very little solute compared to the total solution

Mixing one gram of sugar in 99 mL of water makes 100 grams of dilute sugar solution (a 10 gram sample of this solution only contains 0.1 g of sugar compared to 9.9 g of water)

These four solutions contain the same solvent and solute.

Which one is the most concentrated solution?Which one is the most dilute solution?

A solution is concentrated when there is a lot of dissolved solute compared to solvent ( 5 grams of sugar dissolved in 5 grams of water)

Solubility – the amount of solute that is capable of being dissolved in a solvent

Solubility is often listed as grams dissolved per 100 ml of solvent

Solubility is often given with a temperature because it changes with temperature

Things are called insoluble when they do not dissolve in a given solvent

concentration: the amount of each solute compared to the total solution.

solubility: the amount of a solute that will dissolve in a particular solvent at a particular temperature and pressure.

Solubility of common substances in water at 25oC

Assignment

On the same sheet of paper, (on the third side of the back side), please write six things that you learned from your notes so far that could appear on your test.

Calculating solution volume from solute and concentration

mass of solute

Concentration g/L =

liters of solution

mass of solute

liters of solution =

concentration

Example

If the concentration of a sugar solution is 75 g/L, how much solution do you need if you want 10 g of sugar?

Asked – volume of solution

Given – 10 grams of solute and concentration of 75 g/L

Solve 10 g / 75 g/L = 0.133 liters = 133 ml

If the concentration of a sugar solution is 75 g/L, how much solution do you need if you want 10 g of sugar?

Asked: Volume of solution

Given: 10 g of solute and concentration of 75 g/L

Relationships:

Solve:

mass of soluteLiters of solution

concentration in g L

100.1 13333

75

gL or

gL

Lm

Try

If the concentration of a sugar solution is 90 g/L, how much solution do you need if you want 15 g of sugar?

Asked – volume of solution

Given – 15 grams of solute and concentration of 90 g/L

Solve: g / g/L = liters = ml

Calculating solute mass from solution and % concentration

mass of solute

Concentration % = X 100 Mass of solution

concentration

mass of solute = mass of solution X

100

Example

How much menthol do you need to make 10 kg of mouthwash if the concentration of menthol is 0.05 %?

Asked – mass of solute

Given – 10 kilograms of solution, and concentration of 0.05%

Solve 10 kg X (0.05 / 100) = 0.005 kg = 5 g

How much menthol do you need to make 10 kg of mouthwash if the concentration of menthol must be 0.05%?

Asked: Mass of solute

Given: 10 kg of solution, solute concentration of 0.05%

Relationships:

Solve:

%

100

concentration inmass of solute mass of solution

0.05%10 0.005

105

0kg kg or g

Try

How much menthol do you need to make 17 kg of mouthwash if the concentration of menthol is 0.15 %?

Asked – mass of solute

Given – 17 kilograms of solution, and concentration of 0.15%

Solve kg X ( / 100) = kg = g

Molarity is the number of moles of solute per liter of solution

Molarity helps scientist control the ratios of different molecules in reactions

When chemist know the molarity, they can figure out how many moles are needed, and how many milliliters of solution are needed

To find the molarity you must know how many moles of solute are dissolved in the solution

Steps to finding molarityCalculate the formula massUse the formula mass to figure out how many

moles there areCalculate molarity by dividing the number of

moles by the volume of solution

Example

10 g of citric acid C6H8O7 is added to 500 mL of water. What is the molarity of the resulting solution?

Asked – find the molarity of the solution

Given – amount of solute, citric acid and volume of solution

Molarity = moles of solute / volume of solution

Solve: formula mass (6 x12 + 8 x 1 + 7 x 16)

# moles = 10 g / 192 g/mol = 0.052 moles

Molarity = 0.052 / 0.5 L = 0.104 M

Try

25 g of citric acid C6H8O7 is added to 600 mL of water. What is the molarity of the resulting solution?

Asked – find the molarity of the solution

Given – amount of solute, citric acid and volume of solution

Molarity = moles of solute / volume of solution

Ascorbic acid = Vitamin C

Vitamin C acts as a food preservative by reacting with oxygen (O2)Ascorbic acid

C6H8O6

Asked: Volume of solution

Given: Concentration (1M) and balanced reaction

Relationships:

According to the balanced reaction we need 2 moles of ascorbic acid for every mole of O2.

moles solute

molarityvolume of solution L

How much (volume) of a 1 M ascorbic acid solution will completely react with 0.02 moles of oxygen (O2)?

Asked: Volume of solution

Given: Concentration (1M) and balanced reaction

Relationships:

According to the balanced reaction we need 2 moles of ascorbic acid for every mole of O2.

Solve: That means we need 0.04 moles of ascorbic acid:

Answer: 40 mL of the solution contains 0.04 moles of ascorbic acid, which is enough to react with 0.02 moles of oxygen (O2).

0.040 4

10.04

moles solute molesvolume L L or

molaritL

Mm

y

moles solute

molarityvolume of solution L

How much (volume) of a 1 M ascorbic acid solution will completely react with 0.02 moles of oxygen (O2)?

Class Assignment

Write a three dollar summary of what you learned in this section (be very specific and be very thorough).

Turn to page 66 and answer questions 19 – 29 then turn in the assignment.

Honors Chemistry Homework

page 69 # 47 - 52

Air takes up less space under high pressure.

Standard

Temperature and

Pressure

molar volume: the amount of space occupied by a mole of gas at STP. It is equal to 22.4 L.

0oC

1 atm

Many mixtures are gases, like air Gases can contract and expand to fill the

container they are in Concentration in a mixture is usually given as a

percent by volume (because gases at the same temperature, same pressure have the same volume per mole)

The volume is 22.4 L, the temperature is O oC and the pressure is 1 atmosphere also

know as STP

The air you breathe is a mixture!

Air is made up of a mixture of gases Dry air contains about 78% nitrogen, 21% oxygen

and 1% other gases The air we breath has about 1% moisture in it and

at sea level it has a pressure of 101,325 pascals or 101.325 Kpa (1 atm)

This 101.325 is the total pressure from all the gasses in air

Dalton (a chemist) came up with a law known as the law of partial pressures

Partial pressures

The total pressure in a mixture of gases is the

sum of the partial pressures

of each individual gas in the mixture.

Gas A

Gas BGas C

Gas A Gas B

Gas CTotal pressure

=

+

+

Partial pressure of A

Partial pressure of C

Partial pressure of B

Partial pressures

Test:Test: - - Next week Tuesday or Thursday Next week Tuesday or Thursday

depending on your class. depending on your class.

Homework requirement: Homework requirement: Learn all terms and Learn all terms and conceptsconcepts covered on this topic. covered on this topic.

Make sure you have all assignments Make sure you have all assignments between between page 36 and 69page 36 and 69 completed and completed and turned in turned in by your test date.by your test date.