Sem 1 Final ReviewChapters 1- 5

States of Matter

• Fixed = solid

• Variable shape = liquid

• Variable shape and volume = gas

Physical vs. Chemical

• Physical properties can be measured without changing the substance

• Examples: color, shape, mass, density, conductivity, malleability, melting point

• Chemical properties are only apparent when the substance reacts

• Examples: reacts with oxygen, burns, rusts, decomposes when heated

Elements vs. Compounds

• Elements have only one type of atom – they are listed on the periodic table

• Examples: Ag, Cu, Br2, F2, S8

• Compounds have different types of atoms combined as molecules

• Examples: CO, H2O, NH3

Pure vs. Mixture

• Pure substances are either elements (all same atom) or compounds (all the same molecules)

• Mixtures must have more than one substance.

Homogeneous vs.Heterogeneous

• Homogeneous means the ‘same’ throughout

• All pure substances are homogeneous.

• SOLUTIONS are homogeneous mixtures.

• Examples: air, kool-aid, steel (Fe and C)

• Many mixtures are heterogeneous, different areas have different properties

• Example: chicken noodle soup

Periodic Table

• Families (columns) have similar characteristics

• Important families: alkali metals, alkaline earth metals, halogens, noble gases

• Most elements are metals because most elements have 1,2, or 3 outer electrons

• Metals tend to lose electrons to become cations (+) when they form compounds

Diatomic Elements

• When these elements are alone and uncharged, they will exist as molecules

H2 N2 O2 F2

Cl2

Br2

I2

Atomic Structure

• The nucleus of an atom is made of protons and neutrons

• It is positively charged and VERY small.• The electrons surround the nucleus and

create an electron cloud.• The electron cloud is negatively charged

and 10000x bigger than the nucleus.• Remember – you are mostly empty

space.

Atomic notation

Zn6530

Zn6630

The bottom number is the ATOMIC NUMBER = number of protons.

The top number is the MASS NUMBER = protons and neutrons

Elements with the same # of protons but different # of neutrons are called ISOTOPES.

Zn-65 p = 30 n = 35 e = 30

Zn-66 p = 30 n = 36 e = 30

Ionic Compounds

• Write the correct formula for these:

• Sodium sulfide

• Magnesium oxide

• Iron(III) nitrate

• Aluminum phosphate

Ionic Compounds

• Write the correct formula for these:

• Sodium sulfide = Na2S

• Magnesium oxide = MgO

• Iron(III) nitrate = Fe(NO3)3

• Aluminum phosphate = AlPO4

Naming Compounds

• Write the name for these:

• AlCl3• CrCl3• PCl3• BeI2

• Cu(NO3)2

• NO2

Naming Compounds

• Write the name for these:

• AlCl3 = aluminum chloride

• CrCl3 = chromium(III) chloride

• PCl3 = phosphorous trichloride

• BeI2 = beryllium iodide

• Cu(NO3)2 = copper(II) nitrate

• NO2 = nitrogen dioxide

Scientific Notation• Good notation has only one number

before the decimal.

• All of the digits shown in scientific notation are significant digits.

Decimal notation Scientific notation

0.003505

25500

4.2x103

2.50x10-2

3.505x10-3

2.55x104

4200

0.0250

Significant Figures

• Measure all the marks and estimate one digit between the marks.

• When you write the number, the last digit is always a ‘guess’ because its your estimate.

• All the known digits and your estimate are the ’significant figures’

Counting Sig Figs

• All non-zeros are sig figs (123456789)

• Zeros at the beginning are never sig figs 0.00345

• Zeros bewteen numbers are always sig figs 42005

• Zeros at the end are only sig figs if there is a decimal point 3700 3700. 25.00

Using Sig Figs• Sig figs allow us to round our answers

correctly

• When multiplying or dividing, round to the smallest number of sig figs in the problem

• When adding or subtracting, round to the smallest number of places after the decimal (or the last column with sig figs for ever number in the problem.)

525.55 x 16.2 = 8513.91 (round to 3 sig figs) 8510

525.55 + 16.2 = 541.75 (round to 1 decimal) 541.8

Dimensional Analysis• Use equalities to convert numbers/solve

problems

• Set-up so the units cancel

• Multiply the tops, divide by the bottoms

How many seconds in 3.25 hours?

3.25 hr

1 hr

60 min

1 min

60 secX X =

(3.25)(60)(60) (1)(1)

= 11700 sec

Density• Density = mass/volume

• The density of water is 1 g/mL

• Things that are more dense than water will sink in water. If there are less dense they will float on water.

Put these objects in the cylinder of water.

D = 0.80 g/mL

D = 1.25 g/cm3

1.0 g/mL

floats

sinks