Unit #5 - Matter & Atoms Day 1 - What is Chemistry??? Let’s watch “The Supercharged World of Chemistry!”

Unit #5 - Matter & Atoms

Day 1 - What is Chemistry???

Let’s watch “The Supercharged World of Chemistry!”

What is Matter?

Matter: Anything that has mass and takes up space.

Matter is made up of particles called atoms.

Let’s identify the stuff around

us that is matter

So what is Chemistry again?

Chemistry: the study of the

properties of matter and how

matter changes.

Changes in Matter

Matter can change Examples: Freeze, cut, burn, etc. 2 types of changes

1. Physical changes

2. Chemical changes

Physical Changes

Physical Change: any change that alters the form or appearance of matter, but does not make any substance in the matter into a different substance– You start and end with same thing (see below)

Examples: 1) Change of State:

Physical Changes (cont.)

Examples: 2) Change in shape or form:

Chemical Changes

Chemical Change: a change in matter that produces one or more new substances– Start and end with different substances with

different properties Usually irreversible (can’t change back) Examples: burning, rusting, milk going sour

Molecules in Chemical Changes

The atoms arrange to make a new substance

Signs of Change

Physical– Size– Shape– Texture

Chemical– Temperature– Color– Bubbles/fizzing– Smoke– Smell

Is it a chemical or physical change?

Sugar dissolving in tea

•Chemical Change

•Physical Change

OOPS!

Did it change size, color, shape (Physical Change)?

orDid it become different matter (Chemical

Change)?

Correct!


Logs burning

•Chemical Change

•Physical Change

OOPS!



Change)?

Correct!


Breaking water up by separating it into hydrogen and oxygen

•Chemical Change

•Physical Change

OOPS!



Change)?

Correct!


Cutting paper

•Chemical Change

•Physical Change

OOPS!



Change)?

Correct!


Crushing an aspirin

•Chemical Change

•Physical Change

OOPS!



Change)?

Correct!


Metal rusting

•Chemical Change

•Physical Change

OOPS!



Change)?

Correct!


An egg rotting

•Chemical Change

•Physical Change

OOPS!



Change)?

Correct!


An egg breaking

•Chemical Change

•Physical Change

OOPS!



Change)?

Correct!

Day 2 – Properties of Matter

Egg in water and saltwater demo!

Italian Dressing Demo!

Properties of Matter

Weight Mass Volume Density Solubility

Color Odor Shape Texture Hardness

Weight

Weight: Measure of the force of gravity on an object.

All objects on Earth are attracted toward the center by gravity

Weight changes on different planets with different gravities

On moon, you are 1/6 of what you weigh on Earth

Mass

Mass: amount of matter in an object.

Mass does not change with location

Units of mass: grams (g) and kilograms (kg)

Volume

Volume: the amount of space that matter occupies

Units of volume: liter (L),

milliliter (mL) = cm3

Example: Can of pop is

355 mL

Volume (cont.)

Measuring Solid Objects – – 1) Measure Length, Width

and Height

Volume: L x W x H cm3

2) Drop in Graduated

Cylinder

1 milliliter (mL) = 1 cm3

Density

Density: Relationship between the mass of a material in a given volume.

D = Mass / Volume (g/cm3)

What has a higher density?– Trash bag of sand vs. Trash bag of feathers

Density (cont.)

A block of wood –– Mass = 200 g– Volume = 250 cm3

Density = 200 g / 250 cm3

= 0.8 g/cm3

Water = 1.0 g/cm3

Since Density of wood < Density of water…

Wood will float!

Solubility

Solubility: how much solute will dissolve into the solvent.

Determined by – – 1) Temperature– 2) Pressure

Other Physical Properties of Matter

Color Odor Shape

Texture Hardness

Homework Questions

1) What property of matter is measured in cubic centimeters?

2) How are milliliters related to liters?

3) A plastic box is 15.3 cm long, 9.0 cm wide and 4.5 cm high. What is its volume?

4) A piece of metal has a volume of 38 cm3 and a mass of 277 g.

a) What is its density?

b) Choose the identity of the metal from the following list:

Iron = 7.9g/cm3 ; Tin 7.3 g/cm3; Lead 11.3 g/cm3; Zinc 7.1 g/cm3

Day 3 – States of Matter

States of Matter: Solid

SOLID: Fixed shape, fixed volume, high density, particles extremely close together, vibrate, low energy

Solid H2O: Below 0°C

States of Matter: Liquid

LIQUID: No fixed shape, fixed volume, particles move freely, takes shape of container

Liquid H2O: Between 0-100°C

States of Matter: Gas

GAS: No fixed shape, no fixed volume, particles move freely, large distance between particles

Gaseous H2O: Above 100°C

State of Matter: Plasma

Plasma: gas-like mixture of electrically charged particles

States of Matter: Plasma (cont.)

- Found in EXTREME temperatures like the sun and stars

-Can be made by ionizing a gas

State of Matter Changes

Most substances go through a phase change when heated or cooled.

Model 1: Representations of Molecules in Three Phases

Melting

Freezing

Boiling

Condensation

Heating Curve

Model 2: Temperature of a Substance as Heat is Added Over Time

Changes Between Solid and Liquid

Melting Point: temperature at which a solid changes to a liquid.

Added heat energy makes molecules vibrate faster and faster until they break free from their fixed positions

Water: 0°C

Changes Between Solid and Liquid (cont.)

Freezing Point: temperature at which a liquid turns into a solid.

Opposite of Melting Point

When heat is taken away, particles of a liquid move slower and slower and lose their energy

Water: 0°C

Changes Between Liquid and Gas

Vaporization: change from a liquid to a gas. Particles in liquid gain energy

and speed up to form a gas

Two types:

1) Evaporation: vaporization occurs

on the surface of a liquid

2) Boiling: vaporization occurs below

the surface as well as at the

surface.– Boiling Point: temperature at which

a liquid boils

Changes Between Liquid and Gas (cont.)

Condensation: the change from a gas to a liquid

Opposite of Vaporization energy Example: Dew, Clouds

Change Between Solid and Gas

Sublimation: surface particles of a solid change directly to a gas

Do not pass through liquid state Example: Dry ice = solid carbon dioxide

Day 4 – Grouping Substances

We can group substances by their physical properties. Let’s remember, some of them are:

Weight Mass Volume Density Solubility

Color Odor Shape Texture Hardness

Why do we need to group substances?

Substances may be set apart or combined Mixture: made of two or more substances Heterogeneous mixture:

the different parts can be

seen Homogenous mixture:

evenly mixed so the

different parts cannot be

seen

How can you separate mixtures?

1) Magnetic Attraction -

Example: If you had a

mixture of iron, copper,

silver pellets, you could

remove the iron with a

magnet, because copper

and silver pellets are not

magnetic metals


Filtration-

Example: If you had a mixture of water, salt and sulfur, sulfur would be

removed

-Depends on solubility-

Example: Salt, sugar,

baking soda (soluble)

Flour (not soluble)


Distillation: a liquid solution is boiled Substances with different boiling points will

boil at different temperatures

Evaporation: when waterevaporates, it leaves other

Substances behind

Grouping by other physical properties

Odor: Water vs. Vinegar

Conductivity: metals have varying levels of conductivity

Elements

Element: a pure substance that cannot be broken down into any other substance by a chemical reaction.

The simplest substances Each element has its own physical and

chemical properties

Homework Questions

1) How does a heterogeneous mixture differ from a homogeneous mixture?

2) Why is saltwater a mixture?

3) Imagine a beaker containing water, sand, and salt. The salt is totally dissolved in the water. The contents of the beaker are then poured through filter paper in a funnel over a flask. After 15 days, the flask contains only solid salt particles.

Sand water salt

Soluble material:

Insoluble material:

Solvent:

Day 5 – The Periodic Table of the Elements

How is a calendar organized?

The Periodic Table

Periodic Table: a chart of the elements showing the repeating pattern of their properties.

The Periodic TablePatterns of properties emerged when elements were first arranged in order of increasing atomic mass.

Examples of Early Patterns in the Periodic Table

Fluorine (F) and Chlorine (Cl) are both gases that irritate the lungs and make similar compounds.

Silver (Ag) and Copper (Cu) are both shiny metals that tarnish if exposed to air.

What is Atomic Number?

Atomic Number: The number of protons in the nucleus (the center) of an atom in an element.

Helium has an atomic number of 2 because there are 2 protons in the atom’s nucleus

Atomic Mass: how much one atom weighs, in AMU (atomic mass units)

Periodic Table Boxes

Atomic number is on top

The symbol is in the middle.

– Can be one capital letter like “O” for oxygen

– Can be one capital letter and one lowercase like “Au” for gold

Element name is below that

How is the Periodic Table organized?

Period: Rows (across) are organized by atomic number

Groups or Families: Columns (down) are organized by chemical properties of the elements.

– Each column of elements share things in common like:

How they react to other substances

Ability to rust or burn Magnetic or not

What are the different sections?

Nonmetals: e.g., He Metals: e.g., Cu, Zn Metalloids: elements that have

some of the characteristics of both metals and nonmetals

e.g., B, Si, As

MetalsMost of the elements are metals and they share commonproperties: Luster: shininess Malleability: can be hammered or rolled into flat sheets or other

shapes. Ductility: can be pulled out into a long wire. Conductivity: ability to transfer heat or electricity to another

object.

Alloys

Don’t confuse pure elements like gold, silver, and copper with something called alloys.

Alloys: are mixtures or combinations of pure elements together.

– For example, brass, steel, and bronze are alloys. These are not elements because they can be broken into the elements that formed them.

– Bronze = Copper and Tin

Compounds

Compound: a pure substance made of two or more elements chemically combined.

Chemical Formula: the representation of the elements in the compound and the ratio of atoms.

Examples:

CO2 = Carbon and Oxygen

H2O= Hydrogen and Oxygen

NaHCO3 = Sodium, Hydrogen, Carbon and Oxygen

Day 6 – Simple Compounds and Chemical Formulae

Review:

Compound: a pure substance made of two or more elements chemically combined.

Chemical Formula: the representation of the elements in the compound and the ratio of atoms.

Compounds have properties that are different from the uncombined elements.

Simple Compounds

1) CO2 = 1 Carbon atom and 2 Oxygen atoms

Carbon Dioxide

2) H2O = 2 Hydrogen atoms and 1 Oxygen atom

Water

3) NaCl = 1 Sodium atom and 1 Chlorine atom

Salt

4) CO = 1 Carbon atom and 1 Oxygen atom

Carbon Monoxide

Compounds

Not compounds… He2 , O2 , N2

Two atoms, but only one element

Molecules: when two or more atoms held by a chemical bond form a larger particle.

Chemical Equations

Chemical Equation: a short way to show a chemical reaction, using symbols instead of words.

All chemical equations have a common structure: – What substance do you start with and what you end

with

Chemical Equations

Reactants: substances you have at the beginning.

Products: new substances formed after the chemical reaction.

Reactant + Reactant Product + Product

CaCO3 CaO + CO2

Conservation of Mass

Conservation of Mass Principle: During a chemical reaction, matter is not created or destroyed.

Therefore, the total mass of the reactants must equal the total mass of the products.

Closed System: matter is not allowed to enter or leave. It enables you to measure all of the matter before and after a chemical reaction.

Balancing Chemical Equations

A chemical equation MUST show the same number of each type of atom on both sides of the equation.

Reactants Products

Fe + S FeS


Is this chemical equation balanced?

H2 + O2 H2O


2H2 + O2 2H2O

Now we’re balanced!


How would you balance the following?

____Mg + ____O2 ____MgO

Day 8 – Acids and Bases

Acids

Acid: a substance that tastes sour, reacts with metals and other compounds, and turns blue litmus paper red.

Examples:

Hydrochloric Acid: HCl

Sulfuric Acid: H2SO4

Acids are Sour!

Fruits like lemons, oranges and limes are sour because they are acidic!

They all contain citric acid

Can you think of some other foods that may be acidic?

Acid and Metal Reactions

Corrosive: the quality of acids “eating away” at other materials.

Indicators

Indicator: a compound that changes color when in contact with an acid or a base.

Scientists can use litmus paper to identify an acid.

ACID turns BLUE

litmus paper RED

Bases

Base: a substance that tastes bitter, feels slippery, and turns red litmus paper blue.

Opposite of Acids! Examples:

Sodium Hydroxide: NaOH

Ammonia: NH3

Taste and Feel of Bases

Bases taste bitter! Bases feel slippery!

Turns RED litmus paper BLUE!

(B=Base B=Blue)

Where can you find acids and bases?

Acids– Foods: fruits and vegetables– Body: vitamins, lactic acids, stomach acids– Home: cleaning hard surfaces– Industry: fertilizers, batteries

Bases– Food: baking soda– Home: ammonia cleaners– Industry: making cement and mortar

pH Scale

pH Scale: a range from 0 to 14 to measure if a substance is an acid or a base.

Lower than 7 is acidic Exactly 7 is neutral = pure water Higher than 7 is basic

pH Scale

Demonstration

Day 9 - Atoms

Atom: the smallest particle of an element.

Nucleus: the center of the atom.

The nucleus is made of two subatomic particles:

Proton: a positively charged particle inside the nucleus.

Neutron: a particle inside of the nucleus with a neutral charge.

Atoms are made of protons (+), neutrons, and electrons (-).

Electrons

Electron: a negatively

charged particle outside

of the nucleus. Electrons move rapidly

in every direction in a

“cloud” outside of the nucleus. Atoms have no charge, since the negative charge of

the electron balances with the positive charge of the proton

Diagram of the Atom

Molecules

Molecule: two or more atoms that are joined by a chemical bond.

STUDY ISLAND TIME!

Homework

1) What are the three subatomic particles? 2) How do they differ in their electric

charges? 3) Why do atoms have no electric charge

even though their subatomic particles do? 4) Can a molecule be made of only one

atom? Why or why not?

Documents

Unit #5 - Matter & Atoms Day 1 - What is Chemistry??? Let’s watch “The Supercharged World of Chemistry!”