Nomenclature

Naming Compounds

Chemical Bonding Part 2

Rules for Formulas

All atoms must achieve stable electron configuration (full valence)

The formula must be electrically neutral– The sum of the positive and negative

charges must equal zero

Why do we write the metal first?

Usually the least electronegative element is written first, followed by the more electronegative element

Both in binary covalent and in binary ionic

Electronegativity

Metals First

Metals go first because they are less electronegative than non-metals

How do we name our formulas?

Name the cation first, then the anion

Do not include the numbers in the name

Example:

BaCl2 = Barium Chloride

Transition Metals

Form more than one type of cation

Must use Roman Numerals to distinguish which cation is in the formula

Roman Numerals are ONLY used in the NAME, not in the formula

The Roman Numeral stands for the charge on the cation, NOT THE SUBSCRIPT in the formula

Formula vs. Name

FeN = Iron III Nitride

Cu2O = Copper I Oxide

SnO = Tin II Oxide

SnO2 = Tin IV Oxide

How do I figure out what to name it?

Polyatomic Ions

Ions that are made up of more than one element

The elements stay together and act as one unit in chemical reactions

Together the elements still carry a charge

How does that work?

Na+ + PO43- = Na3PO4

Mg2+ + PO43- = Mg3(PO4)2

How do I figure out what to name it?

What do Ionic Compounds look like?

Ionic compounds form salts

Think of table salt

Cations are smaller than the parent atom

Anions are bigger than the parent atom

The compounds formed become tightly packed spheres of atoms

Sizes of Ions

The Positions of the Centers of the atoms (form a matrix)

Review

Simple Binary Ionic Compounds use the simple names of the ionsTransition Metals with more than one charge use Roman Numerals in the name, not in the formulaPolyatomic ions use the name of the ionNames and formulas are cation first, then the name of the anion