Physical ScienceCHEMISTRY REVIEW

Why do atoms Bond?

Brainstorm:

What is the Octet Rule?

Types of Bonds

Colvalent:

Ionic:

Writing Formulas

When writing a formula it is important to remember that every compound has a charge of zero, unless stated otherwise This means that the charge of the anions (negative)

and cations (positive) will add up to zero

Binary compounds are made of two monatomic ions Monatomic ion are ions that contain only one type

of element (i.e you can find it on the periodic table) Ex Na+, H+, O-2, N-3

Charges are found on the periodic table

Example of binary compounds NaCl, CaCl, KF, Li2O

Polyatomic Compounds These compounds contain polyatomic ions

A polyatomic ion is made up of more than one ion but it acts just like monatomic ions do

Charges and names of polyatomic ions can be found on the back of your periodic tables

**note** polyatomic ions are ALWAYS anions (negative)

Examples: NO3-

CO3-

SO4-

Writing FormulasFind how many of each ion that you

need to make the overall charge equal zeroHint: use the charges to determine how

many atoms you needNa+1 C-4

Ca+2 C-4

Ca+1 (PO4)-3

K O

Na (PO4)

Naming rules Covalent naming:

1. Always write the least electronegative element first

2. The more electronegative element is then written, but to it the suffix –ide is added to it

Ex oxygen- oxide

fluorine- fluoride

nitrogen- nitride

3. We now find the problem of distinguishing between compounds with more than one formula (ex CO, CO2)

To prevent this from occurring we add a greek prefix to the element names

1- mono 6- hexa

2- di 7- hepta

3- tri 8- octa

4- tetra 9-nona

5- penta 10- deca

Note: when an element’s name begins with a vowel, the vowel at the end of the prefix is dropped;Example: monoxide vs monooxide

You Try

NF3

N2O4

OF2

Ionic BondsRules

1. Separate the compound into cations and anions Cations- the name will stay the same

Ex. Ca+2 stays as calcium

Anions- the suffix –ide is added to the element name Ex. Br – becomes bromide Ion

2. To name the ionic compound add the names of the ions together

Ex. CaBr2 calcium + bromide = calcium bromide

Examples:

K2O

CaF2

BaO

Polyvalent metals3. Some metals can have more than one charge

therefore we have to distinguish which charge the metal has

FeO- looking at the periodic table Fe could have a +2 or a +3 charge

To find it’s charge, look at the charge on the anion (and the number of these charges)

Ex. FeO has one anion with a -2 charge, therefore the Fe must balance that charge and have a +2 charge (the total anion and the total cation charges must be equal)

4. Now that the charge on Fe is known as +2, we have to show that in it’s name

We do this by adding a roman numeral to the cation

FeO- Fe has a +2 charge therefore the roman numeral II is added after iron

FeO- iron (II) oxide

1 I 4 IV

2 II 5 V

3 III 6 VI

Note only metals with more than one charge have to have the roman numeral added to itEx. Gallium (Ga) only has one charge; which is

+3, therefore we don’t have to add the roman numeral to it’s name

Use the periodic table to determine which metals can have more than one chargeIn pairs look at the periodic table and list those metals

that can have more than one charge

Balancing Equations

1. Write down the unbalanced equation

2. Draw boxes around each chemical formula- never ever change anything inside the boxes

3. Make an element inventory- write down how many of each element you have

4. Write numbers in front of the boxes to try to get the same number of atoms on each side of the equation

Some of Mrs. Lalonde`s Helpful Hints for balancing equations

Save H for next to last, and O until last.IF everything balances except for O, double all

the coefficients and try again. (Shortcut) Polyatomic ions that appear on both

sides of the equation should be balanced as independent units

Zn + HCl ---> ZnCl2 + H2

KClO3 ---> KCl + O2

Zn + HCl ---> ZnCl2 + H2

S8 + F2 ---> SF6

Fe + O2 ---> Fe2O3

C2H6 + O2 ---> CO2 + H2O