matter matter, does it matter? yes…it does! chemistry is the study of matter and the changes it...

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Matter Matter, does it matter? Yes…it does! Chemistry is the study of matter and the changes it undergoes.

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Matter Matter, does it matter?

Yes…it does!

Chemistry is the study of matter and the changes it undergoes.

Matter

Something is considered to be matter if it:

Has mass

Takes up space What are some examples?

We define matter by using two criteria.

Matter

Not Matter

Ideas

Energy

Happiness

Light

Love

Classifying matter - Why?

1. To organize what we have

2. When things are organized – we know what we have

3. And more importantly, we know what we do NOT have.

Matter

Does it have a fixed formula? Yes No

Substance Mixture*Having a fixed formula *No fixed formula*Cannot be separated by *Can be separated physical means by physical means

Classifying matter

Substances Can it be separated chemically?

No Yes

Element Compound*Simplest form of matter *Two or more elements

*Cannot be broken down further * Can be broken down

*Found on the periodic table

H2O -> H2 + O2

Classifying matter

Substances: element or compound Elements- simplest kind of matter

cannot be broken down any simpler and still have properties of that element!

all one kind of atom. Compounds are substances that can be

broken down only by chemical methods when broken down, the pieces have

completely different properties than the original compound.

made of two or more atoms, chemically combined (not just a physical blend!)

Symbols & Formulas Currently, there are 117 elements -Only 92

of the 115 presently known elements occur naturally.

Elements have a 1 or two letter symbol, and compounds have a formula.

An element’s first letter always capitalized; if there is a second letter, it is written lowercase: B, Ba, C, Ca, H, He

Some elements pair up and only exist as diatomic molecules

Hydrogen, Nitrogen, Fluorine, Oxygen, Iodine, Chlorine, and Bromine are always found as diatomic molecules:

How do I remember this? H N F O I Cl Br •HONClFIBr (say HONKLE-fibber) •BrINClHOF (say Brinckle-hoff) •I Have No Bright Or Clever Friends •ClIF H Bron •HOFBrINCl Twins (twins because they exist in pairs) •There are seven such elements. The first one is the first element Hydrogen; the rest form a 7 on the periodic table: N, O, F across, then going down Cl, Br, I.

Elements vs. CompoundsCompounds can be broken down

into simpler substances by chemical means, but elements cannot.

A “chemical change” is a change that produces matter with a different composition than the original matter.

What does this drawing represent?

Is this a compound, element, or both?

What does this drawing represent?

Is this compound, or element?

Answer: Element

What does this drawing represent?

Is this a compound, element, or both?

What does this drawing represent?

Is this a compound, or element?

Answer: compound

What does this drawing represent?

Is this a compound, element or both?

What does this drawing represent?

Is this a compound, or element or mixture of both?

Answer: both compounds and elements

Unnumbered Figure, pg. 9

Investigating Chemistry, 2nd Edition

© 2009 W.H. Freeman & Company

Identify each of the containers as containing either elements, compounds, or both

Unnumbered Figure, pg. 9

Investigating Chemistry, 2nd Edition

© 2009 W.H. Freeman & Company

Identify each of the containers as containing either elements, compounds, or both

Answers:Elements: bCompounds: a, d, eBoth compounds and elements: c

Classifying matter

Mixtures

Is every sample taken the same?

No Yes

Heterogeneous Homogenous*Every sample is different *Every sample is the same*Usually easy to separate * Called “Solution”

Solute Solvent What gets dissolved Usually water

Copyright © Cengage Learning. All rights reserved

Have variable composition.

Mixtures

Homogeneous Mixture

Heterogeneous Mixture

Having visibly indistinguishable parts; solution.

Having visibly distinguishable parts.

Copyright © Cengage Learning. All rights reserved

Homogeneous Mixtures

Copyright © Cengage Learning. All rights reserved

Homogeneous vs. Heterogeneous Mixtures

Classification of Matter

Describing Matter Properties used to describe matter

can be classified as:

1) Extensive – depends on the amount of matter in the sample

- Mass, volume, calories are examples

2) Intensive – depends on the type of matter, not the amount present

- Hardness, Density, Boiling Point

Properties are…Words that describe matter (adjectives)Physical Properties- a property that can

be observed and measured without changing the material’s composition.

Examples- color, hardness, m.p., b.p.Chemical Properties- a property that

can only be observed by changing the composition of the material.

Examples- ability to burn, decompose, ferment, react with, etc.

Physical Properties Chemical Properties

Temperature AmountColor OdorMelting point SolubilityElectrical conductivity Hardness

Rusting (of iron) Combustion (of coal) Tarnishing (of silver) Hardening (of cement)

Some Examples of Physical and Chemical Properties

Properties of CompoundsQuite different properties than their

component elements.Due to a CHEMICAL CHANGE, the

resulting compound has new and different properties:• Table sugar – carbon, hydrogen,

oxygen• Sodium chloride – sodium, chlorine• Water – hydrogen, oxygen

States Of MatterSolids:

.

States Of MatterLiquids:

Indefinite shape, definite

volume

Take the shape of container

Particles are close

together, but mobile

Particles move slowly

States Of MatterGases:

Indefinite shape

Indefinite volume

Take the shape and volume of container

Particles are far apart

Particles move fast

States Of MatterPlasma: Energized gases

Do not have a fixed volume. They are mostly empty space and can be compressed.

Do not have a fixed shape. They tend to fill the entire container.

States Of MatterHow do we change states of matter?

It requires energy.

What does the energy do?

It makes the molecules move. This causes friction, which results in heat being generated

4th state: Plasma - formed at high temperatures; ionized phase of matter as found in the sun

Solid Liquid Gas

Melt Evaporate

CondenseFreeze

38

Learning Check S1

Match: (1) solid, (2) liquid, or (3) gas.

____ A. Has a definite volume, but shape of the container.

____ B. Its particles are moving rapidly.

____ C. Fills the volume of a container.

____ D. Particles are in a fixed structure.

____ E. Particles are close together, but mobile.

39

Solution S1

Match: (1) solid, (2) liquid, or (3) gas.

_2_ A. Has a definite volume, but shape of the container.

_3_ B. Its particles are moving rapidly.

_3_ C. Fills the volume of a container.

_1_ D. Particles are in a fixed structure.

_2_ E. Particles are close together, but mobile.

Physical vs Chemical Properties

Properties are - Words that describe matter (adjectives)

Physical Properties- a property that can be observed and measured without changing the material’s composition.

Examples- color, hardness, m.p., b.p.Chemical Properties- a property that can

only be observed by changing the composition of the material.

Examples- ability to burn, decompose, ferment, react with, etc.

Physical vs. Chemical ChangePhysical change will change the visible

appearance, without changing the composition of the material.Boil, melt, cut, bend, split, crack Is boiled water still water?

Can be reversible, or irreversibleChemical change - a change where a

new form of matter is formed.Rust, burn, decompose, ferment

How to tell the difference

Physical and Chemical Changes

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Change in the form of a substance, not in its chemical composition. Example: boiling or freezing water

Can be used to separate a mixture into pure compounds, but it will not break compounds into elements. Distillation Filtration Chromatography

Physical Change

Physical Change

Substance may seem different, but the way the atoms link up is the same.

It’s a physical change ifIt changes shape or size

It dissolvesIt changes phase (freezes, boils, evaporates, condenses)

Changes the way the molecules link up

Makes new substances

Chemical Change

It’s a chemical change if….

It burns

Temperature changes without heating/cooling

It’s a chemical change if...

It bubbles (makes a gas)

It’s a chemical change if...

It changes color

It forms a precipitate

What kind of change is it if someone...

Tears up paper?Physical changeMixes salt and water?Physical change

What kind of change is it if someone...

Burns paper?Chemical changeEvaporates salt water?Physical change

What kind of change is it if someone...

Mixes vinegar and baking soda?

Chemical change

Chemical ChangeA change in which one or more substances are converted into different substances.

Heat and

light are often evidence of a chemical change.

Chemical ChangesThe ability of a substance to undergo

a specific chemical change is called a chemical property.• iron plus oxygen forms rust, so the

ability to rust is a chemical property of iron

During a chemical change (also called chemical reaction), the composition of matter always changes.

Recognizing Chemical Changes1) Energy is absorbed or released

(temperature changes hotter or colder)

2) Color changes

3) Gas production (bubbling, fizzing, or odor change; smoke)

4) formation of a precipitate - a solid that separates from solution (won’t dissolve)

5) Irreversibility - not easily reversed

But, there are examples of these that are not chemical – boiling water bubbles, etc.

Conservation of Mass During any chemical reaction, the

mass of the products is always equal to the mass of the reactants.

All the mass can be accounted for:Burning of wood results in products

that appear to have less mass as ashes; where is the rest?

Law of conservation of mass