Chemistry Ch.2 Chemical Names and Formulas

Nomenclature

Rules for writing chemical names and formulas

Compound

Two or more elements joined by chemical bonds

Chemical formulas

Show which elements and how many atoms of each are in a representative unit of a compound

Example of chemical formula

“Co” is the element cobalt; “CO” is a compound of 1 carbon and 1 oxygen

Subscripts

Show the number of atoms of each element. No visible subscript implies only one atom of that element.

Example of subsripts

H₂SO₄ contains _ hydrogen atoms, _ sulfur atom, and _ oxygen atoms

Binary compound

a compound containing just 2 elements.

The names of binary compounds will end in

“-ide”

(Look for two capital letters)

Ex. Which are binary compounds- Al₂O₃ SF₆ H₂SO₄

Al₂O₃ and SF₆

How a chemical is named depends on

the type of compound formed,

i.e. the combination of metals and non-metals

Metal + non-metal

Ionic compound, ex. Al₂O₃

-Ionic compounds containing polyatomic ions

-Ionic compounds containing multivalent metals

Non-metal + non-metal:

Covalent/Molecular Compound, ex. CO₂

Starts with “H”

Acids, ex. H₂SO₄

Metal + metal =

an alloy

Ionic bond

A chemical bond formed by the electrostatic attraction between oppositely charged ions, a metal and a non-metal. “Opposites attract”

Ion

an atom or group of atoms that have a pos. or neg. charge from transferring electrons to/from another atom.

Cation

Pos. charged metal due to giving away one or more electrons. Name does not change.

Cation exaple

Na+1 = sodium ion, Al+3 = aluminum ion

Anion

negatively charged n.m. due to taking one or more electrons. End of name will change to “-ide”.

Anion example

Cl-1 = chloride, O-2 = oxide

All of the ions stick together in a proportion that the net change is

zero

An ionic formula unit represents the

proportion of ions

To name ionic compounds,

write the name of the cation followed by the name of the anion

The subscript is not included in the name.

Naming Ionic Cpds

“salts”

Not all iconic compounds are _____ ; some contain _________

binary, polyatomic ions

Monatomic Ion

a single atom with a charge

Polyatomic Ion

more that one atom that together have a charge. If it contains oxygen, it is also called an oxyanion.