IONS AND THEIR COMPOUNDS

REMEMBER HOW WE CAN PREDICT ION CHARGES FROM THE PERIODIC TABLE

IONIC COMPOUNDS

NaCl

MgCl2

Li3N

AlCl3

K2O

Metal + NonMetal Cations and Anions

both present Overall charge of

compound = 0 Number of electrons

given = number of electrons taken

Examples Pattern:

OVERALL CHARGE MUST = 0

Na+1 + Cl-1 = NaCl

Mg+2 + 2Cl-1 = MgCl2

3Li+1 + N-3 = Li3N

Al+3 + 3Cl-1 = AlCl3

2K+1 + O-2 = K2O

GIVE THE FORMULAS FOR THE COMPOUNDS THAT CONTAIN THE FOLLOWING PAIRS OF IONS

Ca2+ and S2-

Sr2+ and F-

Fe3+ and Cl-

Na+ and S2-

Mg2+ and O2-

CaS

SrF2

FeCl3

Na2S

MgO

NAMING TYPE I IONIC COMPOUNDS

Type I ionic compounds = the metal present forms only one type of cation

Metals in Groups 1, 2, 16 and 18, along with Al (3+), Zn (1+) and Ag (1+).

NAMING TYPE I BINARY IONIC COMPOUNDS

The cation is always name first and the anion second

A simple cation (from a single atom) takes its name from the name of the element. E.g. Na+ is called “sodium” in the names of the compounds containing this element.

A simple anion is named by taking the first part of the element name and adding –ide. E.g. Cl- ion is called “chloride”

Write the name for the compound by combining the names of the ions

“Sodium Chloride”

NAME THESE COMPOUNDS NaI

CaO

CaS

MgO

AlCl3

MgI2

Sodium Iodide

Calcium Oxide

Calcium Sulfide

Magnesium Oxide

Aluminum Chloride

Magnesium Iodide

MORE PRACTICECh 4, p. 119 and 121

Problems 6, 25, 41, and 42

TRANSITION METALS COMPLICATE THINGS

Many transition metals can form more than one cation. These cations have different charges

E.g. Au can form Au+ and Au3+, Fe can form Fe2+

and Fe3+

To indicate these different charges in the names of compounds, chemists use a system of Roman numerals conveying the different “oxidation numbers” of the cations

E.g. AuCl3 is called “Gold (III) Chloride; AuCl is called “Gold (I) Chloride)

The Roman numeral indicates the charge of the cation, NOT the number of ions present!!!!!!!

NAMING TYPE II BINARY IONIC COMPOUNDS

Type II compounds – the metal present can form 2 or more cations that have different charges (this will usually be a transition metal)

Give name of cation, the roman numeral indicating the cations charge, and the name of the anion (the root of the element forming the ion + -ide)

E.g. Fe2O3 = Iron (III) Oxide; FeO = Iron (I) Oxide

NAME THESE COMPOUNDS

HgO

PbCl4

HgCl2

SnBr4

CoCl3

Mercury (II) Oxide

Lead (IV) Chloride

Mercury (II) Chloride

Tin (IV) Bromide

Cobalt (III) Chloride

MORE PRACTICECh 4, p. 118, 122

Problems 8 and 44