ionisation energy Flashcards
what are orbitals
regions of space where electrons are likely to be. they hold two electrons of opposite spins
total number of electrons per shell
2, 8, 18, 32
what is the Aufbau principle?
electrons enter the lowest energy available orbital
what is Hund’s rule
electrons only pair up once there are no empty orbitals on that energy level
define: 1st ionisation energy
the energy required to remove one electron from each atom in one mole of gaseous atoms producing one mole of 1+ gaseous atoms
factors affecting ionisation energy
atomic radius,
shielding,
nuclear charge
how does 1st ionisation energy change down a group
it decreases. the atomic radius increases and so does shielding which overrides the increase in nuclear charge. the attraction is weaker so less energy is needed
the general trend of 1st ionisation energy across a period
it increases. the atomic radius decreases and nuclear charge increases. shielding doesn’t change. the attraction is stronger so more energy is needed
1st ionisation energy change from group 2 to 3 (across period exception)
for group 3 the electron comes from a p orbital. this is further from the nucleus and has shielding from s orbital. this overrides nuclear charge so it requires less energy
1st ionisation energy change from group 5 to 6 (across period exception)
for group 6 the electron comes from a pair. this extra repulsion overrides the nuclear charge. therefore less energy is needed
example equation of 1st ionisation energy of carbon
C(g) –> C^+ (g) + e^-
how can an elements group be identified from successive ionisation energies?
when an electron is taken from a new shell there will be a large jump in ionisation energy. this tells you the number of electrons in the outer shell and therefore its group
