Atoms are usually neutral (same number of protons (+) and electrons (-)). However, atoms want a full outer electron shell (like noble gases - this is the Octet Rule). To achieve this, they can gain or lose electrons.
When an atom gains or loses electrons, it becomes an ion – an atom with an electrical charge.
Opposites attract! The positive cation and the negative anion are pulled together by strong electrostatic forces. This attraction forms an ionic bond, creating an ionic compound.
Ionic compounds form crystal lattice structures, not individual molecules.
Ionic compounds are electrically neutral overall. The total positive charge from the cations must exactly balance the total negative charge from the anions.
Example: Magnesium (Mg²⁺) and Chlorine (Cl⁻).
Polyatomic Ions: Some ions are groups of atoms bonded together with an overall charge (e.g., Sulfate SO₄²⁻). Treat them as a single unit when balancing charges. If you need more than one polyatomic ion, use parentheses: e.g., Ca(NO₃)₂.
Transition Metals: Metals like Iron (Fe) and Copper (Cu) can form ions with different charges (e.g., Fe²⁺ and Fe³⁺). Their names include a Roman numeral to show the charge: Iron(II) for Fe²⁺, Iron(III) for Fe³⁺.