Writing Formulas and Naming Compounds

When compounds form, the net charge always equalszero. The number of + always equals the number of -.

3+3-

Lets picture what happens• Na+ + Cl- are attracted to

each other.

• Na+ and O2- are attracted to each other.

Na+

Na+

Cl-

O2-Na+

NaCl

Na2O

Your turn: Use the following ions to make as many compounds as you can. You may use your ion sheet.

• potassium• magnesium• Gallium• Lithium

• chloride• oxide• hydroxide• phosphide• phosphate

• Cl1-

• O2-

• (OH)1-

• P3-

• PO43-

Li3PGaPMg3P2K3PP3-

Ga(OH)3Mg(OH)2KOH(OH)1-

Li2OGa2O3O2-

KClCl1-

Li1+Ga3+Mg2+K+

MgCl2 GaCl3 LiClK 2O MgO

LiOH

K+ Mg2

+

Ga3+ Li+

Cl-

O2-

OH-

P3-

Potassiumchloride

Potassiumoxide

Potassiumhydroxide

Potassiumphosphide

Magnesiumchloride

Magnesiumoxide

Magnesiumhydroxide

Magnesiumphosphide

galliumphosphide

Oxidation number

• The charge on a monatomic ion is called the oxidation number.

• An ion with more than one atom, has a different oxidation number on each atom, so the sum of the oxidation numbers equals the charge of the ion.

• Your ion sheet lists some common oxidation numbers for metals .

Reading Isotopes

S32

16

2-

Mass number

Charge or oxidation number

atomic number = number of

protons

Reading Isotopes

F19

9

1-

Mass number

Charge or oxidation number

atomic number = number of

protons

What is the oxidation numbers of sulfur in this compound?

CaSO4

2+ 4 of 2- = -8

?

0 = 2 - 8 + ?? = 6

What is the oxidation numbers of phosphorous in this compound?

Na3 PO4

3 sets of 1+

4 of 2- = -8

?

0 = 3 - 8 + ?? = 5

• Write the formula for the following compounds:– calcium

chloride– sodium

cyanide– magnesium

oxide

CaCl2

Na CN

Mg

MAKE SURE THECHARGES AREBALANCED!

O

• Write the formula for the following compounds:– silver and

fluorine– nickel (II) and

sulfur– chromium (III)

and bromine

Ag F

Ni S

Cr

MAKE SURE THECHARGES AREBALANCED!

Br3

4. Write formulas for the following.

• barium sulfate

• barium sulfide

• magnesium phosphate

• strontium bromide

• chromium (III) acetate

• Ba2+

• SO42-

• S2-

• Mg2+

• PO43-

• Sr2+

• Br1-

• Cr3+

• C2H3O21-

BaSO4

BaS

Mg3(PO4)2

…….

mass number = number of protons + number of neutrons

atomic number = number of protons

# neutrons = mass # - atomic #

# electrons = # protons

Explain lead-207’s parts

Pb207

82

mass number

atomic number

Naming Binary inorganic compounds.

Al2S3

Aluminum Al3+

SulfideS2-

K3P

PotassiumK+

PhosphideP3-

The charges not needed for naming most compoundsThe charges are only needed for writing chemical formulas.

Naming Binary inorganic compounds containing transition metals.

Cr2S3

chromium (III)Cr3+

SulfideS2-

Cu3P

copper (I)Cu+

PhosphideP3-

The charges ARE needed for naming these compoundsThe charges are also needed for writing chemical formulas.

To name covalent compounds

• Covalent compounds are composed of two or more nonmetals which share electrons. (Some metalloids are covalently bonded as well).

• USE PREFIXES mono = 1 penta = 5di = 2 hexa = 6tri = 3 hepta = 7tetra = 4 octa = 8

prefix if not mono-nameof less electronegative atom, prefix of second atom– ending ide

Naming covalent compounds

• CO2

• CO

• P2O5

mono = 1 penta = 5di = 2 hexa = 6tri = 3 hepta = 7tetra = 4 octa = 8

• carbon dioxide• carbon monoxide• diphosphorous

pentoxideTry SF6

sulfur hexafluoride

Naming Organic Compounds

• Organic compounds have one or more carbons, surrounded with hydrogens.

• They may have double or triple bonds, and may include oxygen, or other atoms.

• They are named by counting the “carbon backbone” and applying a prefix

• “Functional Groups” provide the rest of the name.

meth = 1eth = 2prop = 3but = 4pent = 5hex = 6hept = 7oct = 8non = 9…

Naming Organic Compounds

• Butane = 4 carbons

• CH3CH2CH2CH3

• Heptane = 7 carbons

• CH3CH2CH2CH2CH2CH2CH3

• Octane = 8 carbons

• CH3CH2CH2CH2CH2CH2CH2CH3

meth = 1eth = 2prop = 3but = 4pent = 5hex = 6hept = 7oct = 8non = 9…