1. chemical bond- link between atoms Nucleus attracts valance electrons
Chem chapt. 7 notes
chemical bond- link between atoms
Nucleus attracts valance electrons
Ionic bond- where 1 atom gives up e and the other takes them - TRADING ELECTRONS
covalent bond- share e in the valance level so both have full shell
Bonds can be pure Ionic or Covalent or somewhere in between (polar covalent),
polar covalent means the electrons are not evenly shared)
nonpolar covalent means even sharing Ca Br

2. if you take something from groups 1-2,
and bond to atom from group 16-17, most likely ionic.
if you bond 2 nonmetals, covalent,
closer atoms are together, less polar they are

3. chart pg have students
Put this chart on their Periodic Table.
Just subtract the electronegativity
And match them to the chart on the next page

4. 4
ionic
1.7
polar .4
nonpolar

5. Octet rule- all atoms gain, lose or share electrons
in order to have a full valance shell.
How many valance electrons do atoms start with? depends on their group- remember group 1 has 1 ( they are a 1s1 or 2s1 or whatever)
group 2-12 have 2, group 13 has 3 up to group 18 which has 8.
sometimes it is useful to draw the valance electrons, in a method called Lewis dot notation

6. the Lewis dot notation
simply shows the valance electrons as dots around the atoms chemical symbol. only hint is to put them top/bottom/left/right, then go back and make pairs. •
Na• •C•
•• •
••Br •• ••

7. Once you know how many valance e- you
How an ion is written-
Once you know how many valance e- you
have you can decide how many it would
lose or gain.
Left half loses, will make positive ions
group one all become + 1 ions Na +1
group 2-12 all are +2 ions, Fe+2
Group , Al +3 group C+/- 4
Right side gains e- become negative
Group , so N-3
GRoup so O -2 and G 17 are -1

8. monatomic ions Na+ and Cl- Ca +2 and P-3
or polyatomic ions
these are groups of atoms with a charge
SO4 -2 or NO3 -1
still put them into reactions the same way. still
balance charges Cl H Cl H Na Cl Cl H

10. covalent compounds
How do you know something is a covalent molecule - it has nonmetals only. H, C, O, N, S, P and a few times the halogens or others will get in the game
To name them - use prefixes to tell how many of each are in the compound
*prefixes for covalent compouns
* mono-1 penta 5 nona-9
di-2 hexa 6 deca-10
tri-3 hepta 7
tetra-4 octa-8

11. technically you only use mono with Oxygen when it is with C, N, or S.
Lets try some!!!
CO carbon dioxide
CO carbon monoxide
NO nitrogen trioxide
N2O3 Dinitrogen trioxide
PCl3 Phosphorus trichloride
H2O Dihydrogen oxide
technically you only use mono with Oxygen when
it is with C, N, or S. O N O C

12. Other notes to know about naming
hydrates- have water bound up in the molecule, so we add the word hydrate to them along with a prefix to tell how many
Copper sulfate pentahydrate CuSO4 5H2O
if that same substance has the water removed it is "anhydrous"
MgSO4 7H2O

13. if it is binary, like HCl HF H2S
Also there are a whole group of compounds called acids,which have hydrogen attached to a molecule
mostly these look like ionic compounds except the positive ion is Hydrogen
if it is binary, like HCl HF H2S
Name these by calling them Hydro ____ ic acid
IF with polyatomic ion, Like H3PO4 or H2SO4
drop the hydro and just use _____ ic acid
there are 2 exceptions-
H2SO3 is sulfurous acid and HNO2 is nitrous acid e

14. characteristics of ionic and covalent molecules!
ionic crystals covalent molecules
never alone, always in lattice much stronger molecules
always polar, can be solids liquids or gases
metal with non metal polar or non polar ( O2, CO2)
gasoline, oil, etc
organic- made of or makes up
living things
all solids brittle crystals will dissolve in water and
in organic
dissolve in water not in organic substances like gasoline
substances
conduct electricity do not conduct electricity
in and of living things- sugars,
proteins, DNA
found in the ground, caves, geods, diatomic ions in the air
found in parts of gems very high melting points
N2 O2 H2 CO2
very low melting points

15. Lets try one! check these statements against your notes and make a guess about what this is!
white powdery substance
dissolves in water
dissolves in rubbing alcohol
melts and burns over bunsen burner
doesn't conduct electricity

16. Gerometry, and lewis structures.
Used for covalent compounds, they show all shared and unshared electrons
Give a picture of a covalent compound, and how all atoms share electrons to have eight.

17. Rules to writing
Count all valance electrons before
Put one atom in middle. It should be carbon if you have it, or whatever atom is single.
If 3 singles, then choose the one with the lowest electronegativity
Put all other atoms around the central atom ( like lewis dots) and fill in lines to show bonds
Now fill in with free electrons, by pairs, till all atoms have 8.
Count valance electrons in picture, they should match the count you made in step one
If they do not match, make double bonds until they do.