ionic+charge

__Metal Ions:__

The general rule of thumb for predicting a metal's ionic charge is that it will lose all of its valence electrons. The number of electrons the metal loses will be numerically the same as its charge.

Because metals lose negatively charged electrons, they will have more protons (positively charged) than electrons, and the net effect of this will make the metal ion positively charged.

Example: sodium metal (not the ion) has one valence electron (it is in group 1). When it becomes ionized, it loses that one valence electron. The sodium ion will therefore have 11 protons and 10 electrons, and will therefore have a +1 charge.

__Nonmetal Ions:__

A nonmetal will gain enough electrons to reach eight electrons (octet rule). Each electron added to its valence shell will increase its ionic charge by -1, because it will have one more electron than it has protons.

Example: the oxygen atom is in group 6, and will have 6 valence electrons. When it becomes an ion, it will gain 2 electrons to have the all-important 8 valence electrons. Therefore as an ion, it will have 2 more electrons than protons, and have a charge of -2.

Watch this video that briefly explains oxidation numbers across the periodic table"

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