What are ionic compounds made up of
A concentration of atoms or groups of atoms where electrons are transferred from one to another
General properties of ionic compounds
- High melting point
- High boiling point
- Hard but brittle (not malleable or ductile)
- Does not conduct electricity in the solid state
- Good conductors in the liquid state or aqueous
- Varies from soluble to insoluble in water
Structure of ionic bonding
- No free moving electrons
- Charged particles are not free to move in the solid state, when it melts they become free to move and conduct electricity
- 3D lattice (crystal lattice
- Large number of cations and anions
What is ionic bonding
The force of electrostatic attraction between oppositely charged ions through the bonding of a non-metal and a metal
Polyatomic ions
- Ions containing 2 or more atoms (can be from different elements)
- Fixed ratio
- Subscripts are used to indicate the ratio of ions in the crystal lattice
Empirical formula
Simplest whole number ratios of particles
What is the valency of an atom
The measurement of its ability to bond with other atoms
What happens to the name of polyatomic ions that contain oxygen
They usually end in ‘ite’ or ‘ate’
What happens to the name of simple non-metals in ionic bonding
They stay the same but end with ‘ide’
What happens to the name of metals in ionic bonding
Nothing, they stay the same
Steps of ionic bonding
- One set of atoms (generally metal) lose electrons and become positively charged ions
- These lost electrons are transferred to the other set of atoms
- The other set of atoms (generally non-metal) become negatively charged ions
Why do ionic compounds have a high melting point
Because a high amount of energy is required to overcome the electrostatic attraction between ions
Electrolyte
A solution or molten substance that conducts electricity by means of the movement of ions
Why do metal atoms lose electrons in ionic bonding
They have weakly held valence electrons due to low ionisation energies and electronegativity
Why do non-metals gain the electrons in ionic bonding
They have strongly held valence electrons due to their high ionisation energies an electronegativity
Rules for writing a chemical formula
- Write the symbol for the positively charged ion first
- Use subscripts to indicate the number of each ion in the formula
- Do not include the charges of the ions in a balanced formula
Rules for writing polyatomic ion formulae
- If different elements are present then they are combined into fixed ratios
- The group of atoms have a single unit with a specific charge
- Subscripts are used to indicate the number of each kind of atom in the ion
What happens if more than one polyatomic ion is required in a formula to balance the charge
Brackets with the required subscript after them are placed
