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Atoms are made of protons, with positive charges, and electrons, with negative charges. When an atom, usually of a metal, loses an electron, it becomes an ion with a positive charge. When an atom of a non-metal gains electrons, it becomes a negative ion. The charge of the ion is determined for metals by subtracting the number of electrons from the number protons and vice versa for non-metals.
Example Sodium (Na) ion with 11 protons and 10 electrons. The net charge is thus:
11 protons....11+
-10 electrons..10-
Net Charge= +1
Therefore the ion is labled Na+1
Ionic Compounds are formed when ions combine. They are represented by empirical formulas not molecular formulas. For example: Sodium Chloride, made up of Na+ ions and Cl- ions, is represented by the empirical formula NaCl. The formula unit is the lowest