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