CHAPTER 4.CHAPTER 4.MATTER & ENERGYMATTER & ENERGY

CHM130GCC

4.1 Three States of Matter:

solid, liquid, and gas Gas: Particles are far apart and are in constant motion.– Gases have no set shape, they assume

shape of the container.– Gases have no set volume, it is variable

If volume increases, particles move farther apart.

If volume decreases, particles move closer together.

Liquid: Particles are close together but are free to flow around one another.

– Liquids assume shape of the container.

– Volume is constant (can’t compress).

Solid: Particles are packed tightly together & organized in a rigid pattern; the atoms vibrate in place.– Solids have a definite, fixed shape.

– Volume is constant.

Cool animations

3 States Of Matter – Scroll down and click on all the states of matter animations and the phase change animation (some may not work which is why there are several options)

Ways to Draw the States of Matter

physical changes – learn these 6 terms

4.2 Definitions• Element – one type of atom only, can be

single atoms (He) or diatomic molecules (O2), cannot be broken down further chemically

• Compound – two or more different atoms bonded together, can be broken down chemically into elements

• Pure – all particles are the same, cannot be physically separated

• Mixture – two or more different particles mixed together, can be physically separated

(top picture is pure element, bottom is pure compound)

Examples•Mixtures

• Metal alloys like 18-K gold, brass• Sand, granite• Tap water • Air which consists of nitrogen, oxygen,

and other trace gases.•Pure

• Salt (NaCl) is a compound• Diamond (carbon) is an element• Distilled water is a compound• Mercury is an element

element compound mixture

For each figure, indicate if it represents an element, a compound, or a mixture

A = element

B = cmpd

C = mix

D = element

E = cmpd

F,G = mix

H = element

4.3 Elements1. Each element has a unique name, symbol,

and number2. Capitalize first letter of element name:

hydrogen H, carbon C3. If there’s a 2nd letter it is lower case: helium

He, calcium Ca, cobalt Co

Careful! CO is carbon monoxide not cobalt

Most symbols are from English names:

hydrogen H; oxygen O; Helium He

Some are from Latin names:

lead Pb (plumbum) gold Au (aurum means “golden dawn”)

KNOW THE NAMES AND SYMBOLS OF THE FIRST 20 ELEMENTS

OF THE PERIODIC TABLE & THE FOLLOWING

Ag silver Au gold Pb lead

Br Bromine I iodine Hg mercury

Let’s name them!Periodic Table: You already know many of these

4.4 nonmetals, semimetals, and metals

(Fig. 4.5)

1. Nonmetals (except H) are located on the right side of the stair-step line

2. Semimetals are touching the stair-step line following B (except Al which is metal)

3. Metals are on the left side of the stair-step line

Properties of Metals vs. Nonmetals

Metals Nonmetals

shiny appearance dull appearance

malleable, ductileAll solids but Hg

Brittle solidsMany gases

density – usually highmelting point - high

density – usually low melting point low

Good conductors of heat & electricity

Poor conductors (make better insulators)

Semimetals (metalloids) Have properties in between

Physical States of the Elements at 25 ˚C and normal atmospheric pressure KNOW THESE

Only mercury (Hg) and bromine (Br2) are liquids

H2, N2, O2, F2, Cl2, and all Noble gases (Group VIIIA) are gases

All other elements are solids

04_06.JPGPhysical States of the elements

7 Diatomic elementsDiatomic means two atoms

bonded together

Have no fear of ice cold Beer!

H2(g) N2(g) F2(g) O2(g) I2(s) Cl2(g) Br2 (l)

Two Diatomic ElementsBromine Br2(l) and Iodine I2(s)

I should be able to point at any element and you tell me 1. Solid, liquid, or gas2. Name (for some of them)3. Diatomic or not4. Metal, semimetal, nonmetal

Let’s play! I’ll point at several elements…

This is how we draw Atoms of an Element

Molecules of an Element if same

2 or more atoms bonded together =

Molecules of a Compound if different

Ex: water = H2O 2 H atoms, 1 O atombut water is not bonded H-H-O

Ex: How many atoms in potassium nitrate = KNO3

___ K, ___ N, ___ O atomsbut it is not bonded K-N-O-O-O

4.5 Chemical formulas tell us

- type of atoms = element symbols

- # of those atoms = subscripts (don’t show 1)

-But NOT their bonding order

1 1 3

Another Example

Ex: (NH4)3PO4

What is the total number of atoms?

How many atoms of each element are present in Viagra: C22H30N6O4S ?

____ C, ____ H, ___ N, ____O, _____S22

30 6 1

(NH4)3 = 3 NH4’s = 3 ( 1 N + 4 H) = 3N + 12 HTOTAL: 3 N, 12 H, 1 P and 4 O’s = 20 atoms

4

Law of Definite Composition

Compounds always contain the same elements in the same proportion by mass.

Ex: H2O always contains 11.2 % H and 88.8 % O by mass whether you have a glass full, a swimming pool or an ocean.

4.6 Physical properties - color, odor, taste, texture, melting point, physical state (s, l, or g), density, solubility, conductivity, hardness

Chemical properties - describe how a substance reacts or behaves. (explosive, corrosive, toxic, inert, reactive, rusts, oxidizes, decomposes, etc.)

4.7 Physical change: a change that keeps chemical composition the same, the molecules stay the same with the SAME formula.

Physical Changes ARE changes in state (s l g)

Ex: boiling water, melting gold, freezing alcohol, breaking glass, dissolving salt in water, dry ice

subliming

Note that the H2O molecules remain H2O regardless of whether the sample is a solid, liquid, or gas; changes in physical state are physical changes

Review Physical Changes – know these terms!

Physical ChangesAtoms are always moving, even in solid state.

When you heat ice, the water particles gain kinetic energy and move faster.

When particles gain enough energy to overcome attractive forces the solid will melt liquid.

If we keep heating the liquid, the particles gain more KE & move even faster gaseous state

Chemical Changes: a process that changes the chemical composition, the molecules break apart and rearrange. The formula CHANGES.

(aka chemical reactions) Starting substance is destroyed and a new substance with different properties is formed.

Ex: burning gas

Indicators of chemical reaction:

These may indicate chemical change

• oxidation of matter (burning or rusting)• release of gas bubbles (fizzing) without

heating (thus not boiling)• formation of solid (precipitation)• release of heat or light• change in color or odor

CHEMICAL REACTIONS

REACTANTS PRODUCTS

Starting substances are called reactants; New substances formed are called products.

Ex: 2 H2 H22 + O + O22 2 H2 H22OO

Ex: Chemical reaction between

sodium metal Na(s) and chlorine gas

Cl2(g). They produce salt, NaCl, which is a

totally different chemical with

different formula and properties than the

reactants.

4.8 LAW OF CONSERVATION OF MASS4.8 LAW OF CONSERVATION OF MASSMatter or mass cannot be created or destroyedMatter or mass cannot be created or destroyed

mass of the reactant(s) = mass of the product(s)

Two reactants make 4.0 grams of product. If one reactant was 1.5 grams, the other was ________2.5 g

4.9 Kinetic Energy - Energy of motion

ExamplesWater flowing over a damWorking outDancingBurning gasoline

Potential Energy- Stored Energy

Examples

Water behind a dam

Gasoline or coal

Chemical bonds in food

Car at top of roller coaster

KE, Temp, and physical state• As kinetic energy increases and molecules

move and vibrate faster, the temperature ____________. As kinetic energy increases a solid will eventually turn into a ____________. And as the KE increases even more it will eventually turn into a ____________.

• KE and T are related directly or indirectly?

• Which state of matter has lowest KE? Highest?

increases

liquid

gas

solidgas

4.10 Law of Conservation of Energy Energy cannot be created or destroyed, only converted from one form to another.

Ex: When we digest food its stored energy (potential) is converted to kinetic energy to do work.

6 Other Forms of Energy

Radiant (light, UV, radiowaves, etc.)

Heat

Chemical (stored in bonds)

Electrical

Mechanical

Nuclear

Chapter 4 Self Test

Page 107•Try # 1, 4-11, 14-16•Answers in Appendix J