Factors that can affect ionisation energies
- nuclear charge
- distance from the nucleus/ nuclear attraction
- shielding
What can affect general trend of increasing ionisation energy.
- different period= new sub-shell
Less/ more shielding - different orbital
Higher or lower energy orbital= more/ less energy needed - spin pair repulsion
Repulsive force between paired electron in orbital
Easier to remove= less energy needed
Describe metallic bonding
Strong electrostatic attraction between
- metal cations
- delocalised electrons
What are delocalised electrons
Electrons shared between more than 2 atoms
Covalent bonding
- electrostatic attraction
- pair of shared localised electrons
- between atom atoms bonded
What affects the strength of metallic bond
- amount of d.e- = stronger
- charge on cation; greater= stronger
Explain properties of metals
- High melting and boiling points;
Strong metallic bonds - Electrical conductors
Delocalised electrons free to move and carry charge - Malleable and ductile;
Layers of same sized atoms able to slide in new positions
W/o breaking bonds
What are alloys and why are they not compounds?
- a mixture of metals
- different sized atoms increases strength of metals; disallows sliding of layer
- not a fixed ratio of mixture
Similarities with ionic and metallic bonding
- strong electrostatic attraction
- giant lattices
Differences between metallic and ionic bonding
- in metallic; attraction is between cation and d.e-
Ionic; between oppositely charge ions - in ionic; involves anions and cations
Metallic; only cations
Describe giant ionic lattices and examples
- ions formed from non- metal and metal
- regulator lattice of oppositely charge ions held by strong ionic bonds
- each ions surrounded by oppositely charged ions
- eg NaCl, CaO
Describe giant metallic lattices and examples
- Metal cations bonded in lattice with d.e-; electrostatic attraction
- charge of cation and no. d.e- reflects metals group in PT
- strength of bond reflects attractive forces
Eg solid aluminium, magnesium
Simple molecular lattices and examples.
- regular 3D structure of molecules
- molecules bonded by weak intermolecular forces; depending on type of molecule
Eg solid HCN N2
Describe giant covalent lattices w/ examples
- 3D structure of atoms bonded by strong covalent bonds
- eg SiO2 Diamond graphite/ graphene
Who do elements in the same group have similar properties
- same no of e- in putter she’ll
- as types of orbital
Describe trend of boiling and melting point from Group 1 to 4
- general increase
- from Na-Al due to increased strength of metallic bonding
- from Al-Si due to covalent bond being stronger than Metalli
Describe turned on melting and boiling point from Group 4 to 5
- big decrease
- from covalent bonds to induced dipole-dipole forces
Describe trend I melting and boiling point from group 5-8
- decreases
- less electrons in molecules/ atoms = weaker bond in instantaneous dipole
Define ‘first ionisation energy’
- energy required to remove one electron
- from each atom in a mole
- of gaseous atoms
Periodicity
Repeating pattern of properties shown across different periods
Describe the change in the first ionisation energy in different orbitals.
When comparing beryllium and boron for example:
The last electrons in B are in the 2p subshell
The last electrons in Be are in 2s sub-shell
2p is a higher energy level than 2s so it is easier to remove an electron from the higher energy level.
Ionisation energy definition.
- The energy required to remove an electron
- From one mole of each gaseous atoms
- To form a 1+ ion.
