What are cations and anions? Explain with examples.

A cation is an ion with a positive charge. Anions are ions
with a negative charge.

An easy way to remember the
difference is;

a ca+ion (the T becomes a plus
sign)

a
negative
ion

When atoms gain or lose
electrons, so that the number of electrons does not equal the number of protons in the
nucleus, the imbalance in electric charge results in a
ion. While it is technically possible for any atom
to form either a cation or anion, in everyday life, the ionic charge is often determined
by the element's location on the periodic table according to its number of valence
electron (those on the outermost part of the atom). Generally speaking, atoms don't want
to have partially-filled electron shells, so they'll gain electrons if that's the
easiest way to fill the shell, or lose them if that's the easiest way to empty the shell
out.

Metals usually form cations, and nonmetals usually
form anions. Groups 1A, 2A, 3A, the D-block transition metals, and the F-block
lanthanides and actinides form cations. Examples include hydrogen, magnesium, iron,
aluminum and uranium. Groups 5A, 6A and 7A form anions - examples include nitrogen,
sulfur and chlorine. Groups 4A and 8A tend not to ionize.