KF Chemistry1st 6 weeks Exam Review

Week 6 CCASeptember 26, 2014

Pure Substances vs. Mixtures

• Pure substance: matter that has a fixed (constant) composition and unique properties. Contains only 1 type element or compound; homogeneous

MixtureMixture: : Contains at least 2 Contains at least 2 PHYSICALLYPHYSICALLY

combined compounds; can be homogeneouscombined compounds; can be homogeneous

or heterogeneousor heterogeneous

Elements• pure substance that cannot be separated into

simpler substance by physical or chemical means.

Compounds

Pure substance composed of two or more different elements joined by chemical bonds.

– Made of elements in a specific ratio that is always the same– Has a chemical formula– Can only be separated by chemical means, not physically

Mixtures• A combination of two or more pure

substances that are not chemically combined. Zn + Cu

• substances held together by physical forces, not chemical

• No chemical change takes place • Each item retains its properties

in the mixture • They can be separated physically

3 classes of MIXTURES

Solution homogenous

Colloid homogenous

Suspension heterogenous

Examples salt water, air

Soot, fog, mayonnaise

Muddy water, Italian dressing

Particle Type ions, atoms Small Clusters Large Clusters

Particle Size

Scatter Light? (TYNDALL EFFECT)

Settle while standing?

Separate by filtration?

small medium large

No

No

No

No

No

yes yes

yes

yes

Mixtures vs. Compounds

http://www.bbc.co.uk/schools/ks3bitesize/science/chemistry/elements_com_mix_6.shtml

Properties of Matter (4D, Level 3)

• Identify each of the following items as a mixture or a pure substance.• - If a mixture, identify as homogeneous or heterogeneous.• - If a pure substance, identify as a compound or an element.

Sample Type of Sample Type of Mixture or Pure

Substance

Gold

Water

Italian Dressing

Milk

Cobalt

Coffee

Calcium Carbonate

Cake Batter

Physical Properties• Physical Property: Can be observed without

changing the substance composition– Ex: Hardness, Color, Conductivity, Malleability, Melting

Point, Boiling Point

• Physical Change: Properties of the material may change, but the COMPOSITION does not

Gallium – MP is 30°C

Water – MP is 0°C

Chemical Properties• Chemical Property: Can ONLY be observed by

changing the substance composition– Ex: Burn, rot, rust, decompose, ferment, explode,

corrode

• Chemical Change: The COMPOSITION of matter ALWAYS changes

• Also called a chemical reaction

Properties of Matter (4A, Level 2)

• Identify the following properties as physical or chemical.Property Physical Property Chemical Property

Temperature

Bond Strength

Calorie Content

Mass

Density

Reactivity

Length

Melting Point

Properties of Matter (4A, level 3)

• Identify the following changes as physical or chemical.Property Physical Change Chemical Change

A rock is crushed

Condensation of water vapor

Pancakes cook

Salt is dissolved in water

An apple is cut

Food is digested

Alcohol evaporates

Ice melts

Extensive vs. Intensive Properties

• Extensive Properties: Depends on amount• Ex: Volume

• Intensive Properties: Depends on type of matter• Ex: Hardness

Properties of Matter (4B, Level 3)

• Identify the following properties as extensive or intensive.

Property Extensive Property Intensive Property

Temperature

Bond Strength

Calorie Content

Mass

Density

Reactivity

Length

Melting Point

States of Matter• Solid:

• Definite Shape • Definite Volume• Incompressible

• Liquid: • Indefinite Shape• Definite Volume• Not Easily Compressed

• Gas: • Indefinite Shape• Indefinite Volume• Easily compressed

Solid Liquid Gases

Density

Viscosity

Compressibility

Structure

Shape

Volume

Movement

Draw a Picture-Nanoscopic Eyes

States of Matter

The Law of Conservation of Mass

Law of Conservation of MassDuring a chemical change, matter is neither created nor destroyed.

According to the law of conservation of mass, how much zinc was present in the zinc carbonate?

A 40 gB 88 gC 104 gD 256 g

(All practice problems are from TEA released TAKS Tests)

In the procedure shown above, a calcium chloride solution is mixed with a sodium sulfate solution to create the products shown. Which of the following is illustrated by this activity?(A) The law of conservation of mass(B) The theory of thermal equilibrium(C) The law of conservation of momentum(D) The theory of covalent bonding

Use SIGNIFICANT FIGURES to answer• All non-zero numbers are significant

EX: 23.4 is 3 sig.figs., 19 is 2 sig.figs., etc.• All zeros between numbers are significant—

EX: 2003 is 4s.f., 2.07 is 3 s.f., 1.009 is 4 s.f. (captive zeros)• All zeros to the right of numbers aren’t significant if there’s no decimal

EX: 1200 is 2s.f., 1000 is 1. (trailing zeros)• All zeros to the left of numbers aren’t significant if there’s no number in front

EX: 0.0045 is 2s.f. (Leading zeros)• All zeros after a number and a decimal are significant EX: 1.00 is 3 s.f. 230.0 is 4 s.f.

When multiplying and dividing, use the least number of significant figures in your answer.When adding and subtracting, use the least number of decimal places in your answer.

LOOK AT YOUR FORMULA SHEET FOR THE RULES! ! !

SIG FIGS-NOW YOU TRY IT

1. 22.4 x 1.2= 5. 561.25 + 105.2=

2. 1036 x 2.00= 6. 124.12 - 104.121=

3. 0.00686/19.00= 7. 343.2 x 510=

4. 1.200/13.686= 8. 100.25 + 68.750=

Scientific NotationOpen (Enter 6.022nd (Blue or Yellow button)EE ( , button above 7)Type in the exponent 23)

Your screen looks like: (6.02E23)

Close )

Open (

EE

2nd

6

.03

DO NOT ENTER x 10

22

(6.02E23)

change these numbers from Standard Notation to Scientific Notation

1) 9872432

2) .0000345

3) .08376

4) 5673

5) 356890

6) 80345

7) 0.00000075

8) 1000

Use this example to help you learn how to find neutrons

Example: Carbon (C)Atomic Number = 6Mass Number = 12

#Protons = 6#Electrons = 6#Neutrons = (mass number) – (atomic number)

= (12) – (6) = 6

Element Name

Symbol Atomic Number

MassNumber

Number of Electrons

Number of Protons

Number of Neutrons

aluminum Al 13 13 13 14

bismuth

calcium 20

copper

iodine 129

82

8

50

30

Isotopes of Carbon Naturally occurring carbon consists of three isotopes, 12C, 13C, and 14C. State the

number of protons, neutrons, and electrons in each of these carbon atoms.

12C 13C 14C 6 6 6

#P _______ _______ _______

#N _______ _______ _______

#E _______ _______ _______

Average Atomic Mass35Cl has atomic mass 34.97 amu (75.76%) and 37C has atomic mass 36.97 amu

(24.24%). • Use atomic mass and relative abundance of each isotope to calculate the

contribution of each isotope to the weighted average.

34.97 x 75.76 = 26.49 amu 10036.97 x 24.24 = + 8.961 amu

100 • Sum is atomic mass of Cl 35.45 amu

Use this worked to example to practice the upcoming problems!

28

Average Atomic Mass of Magnesium

Isotopes Mass of Isotope Abundance 24Mg = 24.0 amu 78.70% = ______

25Mg = 25.0 amu 10.13% = ______

26Mg = 26.0 amu 11.17% = ______

Find the Average Atomic mass of Magnesium

29

Average Atomic Mass of Boron

Isotopes Mass of Isotope Abundance

10B = 10.013 amu 19.8% = ______

11B = 11.009 amu 80.02% = ______

Find the Average Atomic mass of Boron

Contrast & Compare Fission vs. Fusion

ALPHA & BETA DECAY (12B, Level 3)What is the alpha particle?__________________________________________

What is the beta particle?___________________________________________

Define gamma rays________________________________________________