Naming Molecular Compounds & Acids. Molecules Molecule – two or more atoms covalently bound...

Naming

Molecular Compounds & Acids

Molecules

• Molecule – two or more atoms covalently bound together

• Diatomic molecule – two of the same atom bound together

Diatomic Elements

• H, N, O, F, Cl, Br, I or the Magnificent 7• Have No Fear Of Ice Cold Beverages • These elements exist as diatomic molecules in their most

stable state. • For example:

– Br Br2

– I I2

– N N2

– Cl Cl2– H H2

– O O2

– F F2

Binary Molecular Compounds

• Binary covalent compounds contain 2 nonmetals

• No Polyatomic Ions!!!!!

• No Charges!!!!

Naming Binary Covalent Compounds

• Before you can name binary covalent compounds, you MUST know the prefixes!

• Mono• Di• Tri• Tetra• Penta• Hexa • Hepta• Octa • Nona• Deca

• 1• 2• 3• 4• 5• 6• 7• 8• 9• 10

Rules for naming Binary Covalent Compoundsex. N2F4

• Name the prefix for the number of atoms of the first element (ex. Di-)

• Then name the first element (ex. Dinitrogen)• Name the prefix for the number of atoms of

the second element (ex. Dinitrogen tetra-)• Than name the root of the second element

with the ending –ide

(ex. Dinitrogen tetrafluoride)

Note…• If the 1st prefix is mono….DROP IT!

– Ex. CO is carbon monoxide NOT monocarbon monoxide

• When the prefix ends in an o or a, and the name of the element begins with a vowel, the o or a is often dropped– EX. CO4 would be carbon tetroxide NOT carbon

tetraoxide

Examples

• What is the name of N2O4? N2 di nitrogen

O4 tetra oxide

Since oxide begins with a vowel, we will drop the a in tetra Dinitrogen tetroxide

More examples

• Name SO2

S mono sulfur But mono is with the 1st element, so it will

be dropped sulfur O2 dioxide

Sulfur dioxide

More examples

• Write the formula for dichlorine monoxide Dichlorine Cl2 Monoxide O Cl2O

More examples

• Write the formula for disulfur dichloride Disulfur S2

Dichloride Cl2 S2Cl2

Acids

• Acids can be recognized because the start with H

• Examples– HCl

– H2SO4

– HI

Acids

• Acids are in aqueous solution (aq)

• For the purposes of this class, we will assume that if it begins with H, we will name it according to the rules of naming acids

Rule #1 - naming acids• If the anion ends in –ide, the acid will be

named…

• Hydro (root) – ic acid

• Examples• HCl

• Hydrochloric acid

• HI

• Hydroiodic acid

• H2S

• Hydrosulfuric acid

Rule #2 – naming acids• If you have an H plus an anion ending in –ate,

the acid will be named…

• (root) – ic acid

• Examples

• H2SO4

• Sulfuric acid

• HNO3

• Nitric acid

• H3PO4

• Phosphoric acid

Rule # 3 – naming acids• If you have an H plus an anion ending in –ite,

the acid will be named…

• (root) – ous acid

• Examples

• H2SO3

• Sulfurous acid

• HNO2

• Nitrous acid

• H3PO3

• Phosphorous acid

Writing formulas for acids• When writing formulas for acids you MUST

look at the charges of the anion and add as many hydrogens as needed to cancel out the negative charge (because hydrogen is +1)– Example: Phosphoric acid

– Phosphate = PO4-3

– So, phosphoric acid = H3PO4

Remember…

ate ic

ite - ous

More examples

• H2SO3

• H2CO3

• HF• Nitrous acid• Perchloric acid• Iodic acid

• Sulfurous acid• Carbonic acid• Hydrofluoric acid

• HNO2

• HClO4

• HIO3

Rules for Writing Formulas

• Three sets of rules, ionic, covalent, Three sets of rules, ionic, covalent, and acidsand acids

• To decide which to use, decide what To decide which to use, decide what the first substance is.the first substance is.

• If is a If is a metalmetal or or polyatomicpolyatomic ion use ion use ionicionic..

• If it is a If it is a non-metalnon-metal use use covalentcovalent..• If it is If it is hydrogenhydrogen, use , use acidacid rules rules

Hydrates

• Some compounds trap water crystals when they form.

• These are hydrates.• Both the name and the formula needs to

indicate how many water molecules are trapped.

• In the name we add the word hydrate with a prefix that tells us how many water molecules.

Hydrates

• In the formula you put a dot and then write the number of molecules.

• Calcium chloride dihydrate = CaCl22

• Chromium (III) nitrate hexahydrate = Cr(NO3)3 6H2O

Mixed examples(remember to figure out what type of

compound it is 1st!)

• KClO2

• CO2

• H2SO4

• NH4Br

• CuCO3

• Fe2O3

• HClO

• Potassium chlorite• Carbon dioxide• Sulfuric acid• Ammonium bromide• Copper (II) carbonate• Iron (III) oxide• Hypochlorous acid

More Mixed Examples

• Carbon tetrachloride• Phosphorous pentachloride• Aluminum oxide• Copper (II) nitrate• Chlorous acid• Hydrophosphoric acid• Iron (III) hydroxide

• CCl4• PCl5• Al2O3

• Cu(NO3)2

• HClO2

• H3P

• Fe(OH)3