1. 20F Chemistry Review Part 1
This should be review of stuff learned last year-ish…if you don’t remember it, then you have more work to do to get caught up

2. Electron (e-) Proton (p+) nucleus Neutron (n0) nucleus
orbit/energylevel
Proton (p+)
nucleus
Neutron (n0)
nucleus

3. Number of protons and neutrons (p+ + no)
We will not be building Bohr diagrams this course, but you should remember how do use these numbers
Number of protons (p+)
[OR electrons (e-) since atoms are neutral]
Remember electrons are so small as to be essentially “massless” – the whole mass of the atom is really just the number of p+ and no in the nucleus
Number of protons and neutrons (p+ + no)

4. Atoms that have the same number of protons but a different number of neutrons are called Isotopes.
At Mass = 1
At Number = 1
At Mass = 2
At Number = 1
At Mass = 3
At Number = 1
These are ALL considered Hydrogen
– based on the proton number

5. An atom that has lost or gained an electron is called an ion
Atoms can either gain or lose electrons
Gain - negatively charged ion
Lose - positively charged ion H
neutral atom H+
positive ion
(cation) H-
negative ion
(anion)
An atom that has lost or gained an electron is called an ion

6. Octet rule: atoms react to acquire a full outer shell:
Called valence shell
Gain an e- from another atom
Lose an e- to another atom
Share an e- with another atom
Ionic bond
Covalent bond
Note
Metals typically lose e-
Non-metals typically gain e-

7. NOTE
These numbers might be called “combining capacity” “valences” or “charges” +1 +3 -3 -2 -1 +2
+4/-4
Non-metals
gain e-
Metals lose e-
Remember: The number of the column is equal to the valence electron number. Know that and you figure out the number of electrons lost or gained – the ionic charge

8. Mg Cl Cl S Cl Cl MgCl 2 SCl 2 ionic compound covalent compound - +2 -
metal
non-metal
non-metal
non-metal
MgCl 2
SCl 2
ionic compound
covalent compound - +2 Mg Cl Cl S - Cl Cl
Gain / lose – called a “formula unit”
Sharing – called a “molecule”
A compound has different characteristic properties than the atoms which form it.

9. I Have No Bright Or Clever Friends
Diatomic Elements:
Elements that are most commonly found in a
covalent bond with itself (not as single atoms)
I Have No Bright Or Clever Friends
I H N Br O Cl F2
NOTE
“Greediest” elements that must have a full octet, so they covalently bond with themselves when alone – BUT when bonded to another element there is no longer a reason to be diatomic

10. Notice: oxygen is not diatomic in a bond…
Chemical formula gives the following information:
The different elements in the compound
The number of atoms in the compound
Notice: oxygen is not diatomic in a bond…

11. Remember the subscript applies to what is directly in front of it
Brackets: subscripts outside a bracket multiply by everything inside the bracket. 3
Mg(NO3)2 1 1
Coefficient: total # of molecules present O N Mg O N
Remember the subscript applies to what is directly in front of it
Mg: 1 · 3 = 3
N: 1 · 2 · 3 = 6
O: 3 · 2 · 3 = 18

12. Subscripts · Coefficients (type)
Compound
Coefficient
Total of each element
Subscripts · Coefficients (type)
2 NaNO3 2
Na: 1 · 2 = (I) formula unit
N: 1 · 2 = 2
O: 3 · 2 = 6
2 Al(NO3)3
Al: 1 · 2 = (I) formula unit
N: 1 · 3 · 2 = 6
O: 3 · 3 · 2 = 18
3 Ca(OH)2 3
Ca: 1 · 3 = (I) formula unit
O: 1 · 2 · 3 = 6
H: 1 · 2 · 3 = 6
4 H2(SO4) 4
H: 2 · 4 = (C)molecule
S: 1 · 1 · 4 = 5
O: 4 · 1 · 4 = 16

13. Writing Ionic Compound Formula
1. Write the symbol of the metallic element first.
2. Place the combining capacity (charge) of one element
as a subscript of the other element.
3. Leave subscripts with a value of 1 out.
4. Reduce the subscripts if possible.
beryllium combines with chlorine + 2 - 1
Be Cl
Be Cl2 1

14. Naming Ionic Compounds
1. Write the full name of the metal ion first.
2. Name the non-metal ion dropping the ending and
adding the suffix “ide.”
beryllium combines with chlorine
BeCl2
beryllium
chlor
ide

15. Here is an example of “reducing” the subscripts
Magnesium combines with Sulfur + 2 - 2
Mg S
Mg S
magnesium
sulph
ide
Here is an example of “reducing” the subscripts

16. Transition metals

17. Transition metals can give away different numbers of electrons.
To avoid confusion:
Brackets are used to show the number of electrons the Transition metal is giving away.

18. Fe Cl Fe Cl FeCl2 FeCl3 Iron (III) chloride Iron (II) chloride + 2 - 1
1. Write the symbol of the metallic element first.
2. Place the combining capacity (charge) of one element
as a subscript of the other element.
3. Leave subscripts with a value of 1 out.
4. Reduce the subscripts if possible.

19. Pb O PbO lead oxide (IV) +4 -2 Write the name of the ionic compound: +1
Pb O
PbO 1 2 2
lead oxide
(IV)
Remember: Always look at the anion to see if it has been reduced. If it has, so has the metal.

20. Prefix Number of Atoms mono 1 di 2 tri 3 tetra 4 penta 5 hexa 6 hepta7
octa 8
nona 9
deca 10
Memorize this…

21. Writing Covalent Compound Formula
1. Write the symbol of each element.
2. Use a subscript to show the number of atoms as indicated by the prefix.
*Do NOT reduce covalent bonds
Prefix
Number of Atoms
mono 1 di 2
tri 3
tetra 4
penta 5
hexa 6 di
phosphorus oxide
penta
P O 2 5

22. Naming Covalent Compounds
1. Write the first non-metal with the appropriate prefix.
*We don’t use “mono” for the first non-metal
2. Write the second non-metal with the appropriate prefix and add the suffix “ide.”
N O 2 4
Prefix
Number of Atoms
mono 1 di 2
tri 3
tetra 4
penta 5
hexa 6 di
nitrogen
tetra
oxide
dinitrogen tetroxide

23. OCl2 oxygen dichloride MgCl2 magnesium chloride CuCl2
Does it have a metal?
YES (ionic)
Is it a transition?
NO (covalent)
NO charges
NO criss-cross
Use prefixs
Ends in “ide” NO
YES
Find charges
Criss-cross
Ends in “ide”
Find charges
Reverse Criss-cross
Use Brackets
Ends in “ide”
OCl2
oxygen dichloride
MgCl2
magnesium chloride
CuCl2
copper (II) chloride