Electrons and Bonding

Number of electrons in shells

Shell 1: 2 electrons (1 s orbital)
Shell 2: 8 electrons (1 s orbital, 3 p orbital)
Shell 3: 18 electrons (1 s orbital, 3 p orbital, 5 d orbital)
Shell 4: 32 electrons (1 s orbital, 3 p orbital, 5 d orbital, 7 f orbitals)
2n^2

An orbital can hold up to 2 electrons
s - orbital = spherical
p - orbital = dumbbell shape

Orbital filling order

1s, 2s, 2p, 3s, 3p, 4S, 3D, 4p, etc

  • within each shell, the new type of sub shell added has a higher energy.
  • the 3d sub shell is at a higher energy level than the 4s sub shell
  • therefore 4s sub shell fills before 3 d

Electrons have opposite spins because they are negative therefore they repel each other.
electrons have spin which is either up or down

s sub-shell: 2 electrons
p sub-shell: 6 electrons
d sub-shell:10 electrons
f sub shell: 14 electrons

One electrons occupy each orbital before pairing starts (bus method)

Ionic Bonding

  • The electrostatic attraction between
    positive and negative ions.
  • between metal and non-metal

Covalent Bonding

  • The electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms
  • between 2 non-metal

High boiling point and High melting point because a lot of energy is needed to overcome the strong electrostatic attraction between oppositely charged ions

Ionic compound dissolve in polar solvents.

Ionic compound conducts electricity in aqueous/molten state but not in solid state

  • the overlap of atomic orbital, each containing one electron, to give a shared pair of electrons
  • the shared pair of electrons is attracted to the nuclei of both the bonding atoms
  • the bonded atoms often have outer shell with the same electron structure as the nearest noble gas

Dative covalent/coordinate bond

A covalent bond in which the shared pair of electrons have been supplied by one of the bonded atoms only

Metallic bonding

Is the strong electrostatic attraction between cations and delocalised electrons

High melting and boiling point

High electrical conductivity

Insoluble

Simple Molecular Substance

Solubility

  • non-polar molecules are only soluble in non - polar solvent
  • polar molecules are soluble in polar solvent

Compound doesn't conduct electricity

Relatively low boiling and melting point

Giant Covalent

High melting and boiling

Insoluble

Some Covalent lattices can conduct electricity like graphite/graphene but not like diamonds or silicon