Many metals form ionic bonds when they react with non-metals. Compounds so formed are known as ionic compounds.
Ions: Positive or negative charged atoms are known as ions. Ions are formed because of loss or gain of electrons. Atoms form ion to obtain electronic configuration of nearest noble gas, this means to obtain stable configuration.
Positive ion: A positive ion is formed because of loss of electrons by an atom. Following are some examples of positive ions.
Sodium forms sodium ion because of loss of one electron. Because of loss of one electron; one positive charge comes over sodium.
Na ⇨ Na+ + e−
Similarly; potassium gets one positive charge by loss of one electron.
K ⇨ K+ + e−
Magnesium forms positive ion because of loss of two electrons. Two positive charges come over magnesium because of loss of two electrons.
Mg ⇨ Mg+ + + 2e−
Similarly calcium gets two positive charges over it by loss of two electrons.
Ca ⇨ Ca+ + + 2e−
Negative ion: A negative ion is formed because of gain of electron. Some examples are given below.
Chlorine gains one electron in order to achieve stable configuration. After loss of one electron chlorine gets one negative charge over it forming chlorine ion.
Cl + e− ⇨ Cl−
Similarly, fluorine gets one negative charge over it by gain of one electron forming chloride ion; in order to achieve stable configuration.
F + e− ⇨ F−
Oxygen gets two negative charge over it by gain of two electrons forming oxide ion; in order to obtain stable configuration.
O + 2e− ⇨ O− −
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