1. Sem 1 Final Review Chapters 1- 5

2. States of Matter Fixed = solid Variable shape = liquid
Variable shape and volume = gas

3. 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

4. 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

5. Pure vs. Mixture
Pure substances are either elements (all same atom) or compounds (all the same molecules)
Mixtures must have more than one substance.

6. 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

7. 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

8. Diatomic Elements
When these elements are alone and uncharged, they will exist as molecules
H N2 O2 F2
Cl2
Br2 I2

9. 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.

10. Atomic notation Zn-65 p = 30 n = 35 e = 30 Zn-66 p = 30 n = 36 e = 30
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 p = 30 n = 35 e = 30
Zn p = 30 n = 36 e = 30

11. Ionic Compounds Write the correct formula for these: Sodium sulfide
Magnesium oxide
Iron(III) nitrate
Aluminum phosphate

12. Ionic Compounds Write the correct formula for these:
Sodium sulfide = Na2S
Magnesium oxide = MgO
Iron(III) nitrate = Fe(NO3)3
Aluminum phosphate = AlPO4

13. Naming Compounds Write the name for these: AlCl3 CrCl3 PCl3 BeI2
Cu(NO3)2
NO2

14. 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

15. 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
25500
4.2x103
2.50x10-2
3.505x10-3
2.55x104
4200
0.0250

16. 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’

17. Counting Sig Figs All non-zeros are sig figs (123456789)
Zeros at the beginning are never sig figs
Zeros bewteen numbers are always sig figs
Zeros at the end are only sig figs if there is a decimal point

18. 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.)
x 16.2 = (round to 3 sig figs) 8510
= (round to 1 decimal) 541.8

19. 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?
60 min
60 sec
(3.25)(60)(60)
3.25 hr
11700 sec = = X X
(1)(1)
1 hr
1 min

20. 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.
floats
D = 0.80 g/mL
1.0 g/mL
D = 1.25 g/cm3
sinks