Periodicity Flashcards
Metallic Lattice
Li, Be, Na, Mg, Al, K, Ca
Covalent Molecular
H2, N2, O2, F2, CL2, P4, S8 and fullerenes (e.g. C60)
Covalent Network
B, C (diamond & graphite), Si
Monatomic
Noble Gases
What is the covalent radius?
It is the measure of the size of an atom.
What happens to the covalent radius across a period?
Across a period - the covalent radius decreases as the nuclear charge increases (higher nuclear charge pulls the electrons in closer)
What happens to the covalent radius down a group?
Down a group - the covalent radius increases as the number of occupied shells increase (more shells = bigger atom)
Describe the first ionisation energy
It is the energy required to remove one mole of electrons from one mole of gaseous atoms.
Describe the second ionisation energy
It is the energy required to remove the 2nd mole of electrons.
What happens to the ionisation energy across a period?
Across a period - the ionisation energy tends to increase as the nuclear charge increases.
What happens to the ionisation energy down a group?
Down a group - the ionisation energy decreases as there are more shells, which means there is an increases shielding effect due to the inner electrons (makes it easier to remove the outer ones)
Definition of Electronegativity:
electronegativity is the measure of attraction an atom involved in a bond has for the electrons in a bond.
What happens to electronegativity across a period?
Across a period - the electronegativity values increase due to the nuclear charge increasing (higher positive nuclear charge will mean the negative electrons will be more attracted)
What happens to electronegativity down a group?
Down a group - the electronegativity decreases, this is due to the screening effect (of the inner shell electrons) - they will ‘shield’ the nuclear charge.
