In generalAn ion is an atom or group of atoms with a charge. This means
that the ion has gained (- ions) or lost (+ ions) 1, 2, 3, or 4 electrons. A
single atom with a charge is called a "simple ion" and a "polyatomic ion" is a
group of atoms with a charge (OH-, NH4+,
MetalsMetals form + ions... their names often end in "-ium."
"-ides"Negative ions end with "-ide", "-ate", or "-ite." Single atoms
end with "-ide" (exception... hydroxide). See below for the 1-, 2-, and 3-
"-ates"When you see an ion whose name ends in "-ate," the ion has many
oxygen atoms. How many and what the charge is must simply be memorized.
"-ites"Once you have the "-ates" memorized, the "-ites" are easy... the
same charge, but one LESS oxygen atom.
Families I, II, III, VI, and VIIAt least 15 of the ions are easy
because their charge can be determined from their position on the periodic
The 1+ IonsThe elements in the first column of the table
(H+, Li+, Na+, K+, etc.) all form 1+
ions. WHY?... they lose one electron to have the same number of electrons as the
stable noble gases.
The 2+ ionsThe elements in the second column of the table
(Mg2+, Ca2+, Sr2+, Ba2+, etc.)
WHY?... these lose TWO electrons to have the same number of electrons as the
stable noble gases.
The 3+ ionAluminum forms a 3+ ion.
The 1- IonsThe family (VIIA) next to the noble gases all form 1- ions
(F-, Cl-, Br-, I-). WHY?... these
atoms GAIN 1 electron to have the same number of electrons as a noble gas. Note
that H CAN form "hydride," the H- ion...
The 2- IonsFamily VIA elements form 2- ions, O2- and
S2- (also, Se2- and Te2-). Same reasoning...
the atoms GAIN 2 electrons to have the same number of electrons as noble
The 3- IonsN, P, As, and Sb form 3- ions as they gain 3
Metals with TWO ValencesMercury, Tin, Copper, and Iron have two
forms... there is no rule to help you with the charges... but the smaller charge
ends with "-ous" and the higher charge ends with "ic."
Miscellaneous TipsWhen you see "bi-" (bicarbonate, bisulfate, etc.)
just add in a H+ ion and adjust the charge...
There is a series of ions
There is also
a series like this with bromate and iodate.
Last Tip... practice,