You will learn: to write and read 4 types of chemical formulas

1. Ionic Compounds

2. Polyatomic Compounds

3. Molecular Covalent Compounds

4. Acids/ Bases

When 2 or more elements are chemically combined they are called a molecule or compound.

H2 + O2 H2O

Na + Cl NaCl

atom is the smallest whole unit of an element…….

A molecule is the smallest whole unit of a compound……..

Writing Chemical Formulas

Regardless of where or how a pure chemical compound is prepared, it is composed of a fixed proportion of elements.

“If it is water

it is always 2 hydrogen for every one oxygen… H2O

If it is carbon dioxide

it is always one carbon for every 2 oxygen…CO2…

**Law of Definite Proportions** **Law of Definite Proportions**

• Remember:– Valence Outer shell electrons involved in chemical reactions

– Octet Rule: Most stable condition is 8 electrons in outer shell

– Oxidation #: a + or – number which tells how many electrons were lost

gained

shared when bonding atoms.

Label empty periodic chartLabel empty periodic chart

Writing Ionic Binary Compounds(metal + nonmetal) ws 7.1

1. Write + oxidation number atom first 2. Write – oxidation number atom second3. Do cross-over method for subscripts4. The compound is in a neutral or “ground state”. The formula’s oxidation #’s must add up to equal zero. 5. Must have lowest common factor

Na + N Ca + P

Ba + F Mg + O

Ba + Sb Li + S

Ca + O Sc + Al

1. Write first element name2. Drop last syllable of second element and add ide 3. Transition metals use Roman Numerals to show

oxidation #

• LiF CuCl

NaBr CuCl2

KI FeO

Naming Binary Ionic Compounds

(Stock System) ws 7.2

Ternary Compounds

Polyatomic Ions Poly = many atoms in a group

When writing these formulas use the group as a whole.

Ca + ClO3

Na + SO4

NH4 + PO4

No need to use ( ) if only one group worksheet 7.3, 7.4

1. Nonmetals only 2. Prefixes give the number of each element

( show numbers)3. Second element ends in ide4. O or A at end of prefix is dropped if element

begins with a vowel. { monoxide … not---monooxide}{pentoxide … not– pentaoxide}

P4S5 tetraphosphorus pentasulfide

Si2Br6 disilicon hexabromide

CH4 carbon tetrahydride ws-7.7

Naming Molcular Compounds

Writing Formulas for Molecular Covalent Compounds NM + NM

• Follow wording… do NOT figure oxidation #

Antimony tribromide

Hexaboron monosilicide

Chlorine dioxidews 7.8

formulas for Molecular Covalent = NM+Nm

1. Make sure Nonmetals + Nonmetals

2. The less electronegative element is written first

3. The element written second will keep its normal negative oxidation #.

4. The first element will keep its normal oxidation # but will be positive.

5. Use the cross-over method

6. The algebraic sum of the ox# must equal zero

1. make sure NM + NM 2. The less electronegative element is written first3. The element written second will keep its normal negative oxidation #. 4. The first element will keep its normal oxidation # but will be positive. 5. Use the cross-over method6. The algebraic sum of the ox# must equal zero

Nitrogen + fluorine

Oxygen + sulfur

Phosphrous + chlorine

Bromine + carbon

Naming Acids 2 common types of Acids

Binary Acids OxyacidsHydrogen + one other element hydrogen + Polyatomic

w/Oxygen Hydro + root name & ic Root name + Suffix + acid

HBr hydrobromic acid If polyatomic ended in ‘ate’

HCl hydrochloric acid (NO3)- nitrate ion then

H2S hydrosulfuric acid HNO3 = nitric acid

HCN hydrocyanic acid (SO4)-2 sulfate ion then

H2SO4 = sulfuric acid

“notice hydrogen not part of name”

It is important to remember that these hydrogen – containing compounds are named as acids only when they are in water solutions.

Example: HCl----hydrogen chloride is a gas. But dissolved in water it is hydrochloric acid.

Memorize: HCl hydrochloric acid HNO3 nitric acid H2SO4 sulfuric acid

HC2H3O2 acetic acidH2CO3 carbonic acid H3PO4 phosphoric acid

We will learn more acids and bases in chapter 17 later I would put these on an index card

Acids and Bases

Six Acids to memorize

Hydrochloric

Nitric

Sulfuric

Phosphoric

Carbonic

Acetic

Bases:

metal + hydroxide

Sodium hydroxide

Potassium hydroxide

Calcium hydroxide

4 ways to name chemicals1st step----make sure you know

which method

M+NM NM+NM Ternary Compounds Acids

Nameing Oxyanions