Electrons and Bonding.

• Shells are energy levels.
• As the shell number increases, the energy increases.

Orbital: A region around the nucleus that can hold up to two electrons with opposing spins.

S Orbital

• Each shell contains one S orbital.
• It can hold up to 2 electrons as it has one orbital.

P Orbital

• Contains 3 oribitals and can hold up to 6 electrons.

The 4s subshell is filled first and loses electrons before the 3d subshell.

The electrons fill in separate shells first and then start filling up.

Shorthand configurations

• Put the previous noble gas in brackets.
  
• Fill in the rest a normal.

Ionic bonding: The electrostatic attraction between positive and negative ions.

• Metal ion = positive ion = cation
• Non-metal ion = negative ion = anion

To draw

1. Dots and crosses.

2. Square brackets.

3. Charges (small number after brackets).

4. Amount (large number in-front of brackets).

Each ion is surrounded by oppositely charged ions. These ions attract each other from all directions, forming a giant ionic lattice.

Properties

High melting and boiling points;

• Solid at room temperature.
• A lot of energy is needed to break the strong electrostatic forces.

Electrical conductivity;

• Ions aren't free to move as they are held in a fixed giant ionic lattice.
  

Metallic bonding: The attraction of positive ions to delocalised electrons.

High melting and boiling points;

• Attraction between the positive ions and delocalised electrons is strong. More energy is needed to break the metallic bonds and dislodge the ions from their ridgid structure.

Good electrical conductivity;

• The delocalised electrons can move freely anywhere within the metallic lattice.

Ductile;

• Permits metals to be drawn into wires.

Malleable;

• Can be hammered into thin sheets as delocalised electrons 

Metallic bonding: The attraction of positive ions to delocalised electrons.

High melting and boiling points;

• Attraction between the positive ions and delocalised electrons is strong. More energy is needed to break the metallic bonds and dislodge the ions from their ridgid structure.

Good electrical conductivity;

• The delocalised electrons can move freely anywhere within the metallic lattice.

Ductile;

• Permits metals to be drawn into wires.

Malleable;

• Can be hammered into thin sheets as delocalised electrons can move, the metallic structure is in layers that can slide over each other.

Covalent bond: Strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms.

The attraction is localised, solely acting between the shared pair of electrons and the nuclei of the two bonded atoms.

Dative covalent bond: A covalent in which the shared pair of electrons has been supplied by one of the bonded atoms only.