What is an ion?
An atom or group of atoms that has a net electric charge because it has lost or gained electrons.
What is a cation?
A positively charged ion formed when an atom loses electrons. Example: Na⁺
What is an anion?
A negatively charged ion formed when an atom gains electrons. Example: Cl⁻
Why do atoms form ions?
Atoms form ions to achieve a full outer electron shell
Which type of elements usually form cations?
Metals usually form cations.
Which type of elements usually form anions?
Non-metals usually form anions.
In ionic compounds
what must the total charges do?
Write the formula for sodium chloride using ions.
Na⁺ + Cl⁻ → NaCl
Write the formula for magnesium chloride using ions.
Mg²⁺ + 2 Cl⁻ → MgCl₂
How do you determine the subscripts in an ionic compound formula?
Balance the total positive and negative charges so the compound is neutral.
In an ionic compound formula
which ion is written first?
How do you name NaCl?
Sodium chloride
How do you name MgCl₂?
Magnesium chloride
What is a polyatomic ion?
An ion made of two or more atoms that acts as a single charged particle. Example: SO₄²⁻
Give an example of an ionic compound with a polyatomic ion.
Calcium sulfate → Ca²⁺ + SO₄²⁻ → CaSO₄
Why are subscripts important in chemical formulas?
Subscripts show the correct number of each ion needed to balance charges in a neutral compound.
