Ions and Ionic Bonds

An ion is an atom or group of atoms that have either lost or gained electrons, giving it a net charge.
When an atom loses one or more electrons, it becomes a positive ion or a cation.
When an atom gains one or more electrons, it becomes a negative ion or an anion.
The number of protons remains the same during ion formation, it’s the electron count that changes.
Isotopes can also form ions by gaining or losing electrons.
Transition metals, found in Groups 3-12 of the Periodic Table, can form multiple types of ions with different charges.

An ionic bond is the electrostatic force of attraction between oppositely charged ions. It typically occurs between a metal and a non-metal.
The formation of an ionic bond involves the donating and accepting of electrons. The metal atom donates, and the non-metal atom accepts to complete their outer electron shells.
The structure formed by the ions in an ionic compound is called an ionic lattice. This lattice is a regular repeating pattern of ions, extending in three dimensions.
Ionic compounds tend to have high melting and boiling points because of the strong electrostatic forces holding the ions together in the lattice.
Most ionic compounds are soluble in water because water molecules can pull the ions away from the lattice.
An ionic compound in the molten state or dissolved in water can conduct electricity because the ions are free to move and carry charge.

When writing the formula for an ionic compound, the overall charge should be zero, as compounds are neutral.
The charge of each ion is considered to ensure the compound is neutral. If one ion is +2 and the other is -1, for example, it would require two of the -1 charged ions to balance the charge.
In a stable ionic compound, the sum of the charges on the cations is equal to the sum of the charges on the anions.
The formula of an ionic compound is written as the symbol of the cation followed by the symbol of the anion.
Subscripts are used to indicate the number of ions needed to balance the charge in the compound.
For example, the formula for sodium chloride is NaCl because one sodium ion (Na+) and one chloride ion (Cl-) are needed to balance the charge.