Chemistry- ionisation energy (copy)

what is first ionisation energy?

energy required to remove one electron

from each atom

in a mole

of gaseous atoms

what is second ionisation energy?

energy required to remove the second electron (NOT BOTH ELECTRONS)

factors impacting ionisation energy??

• atomic radius

• nuclear charge

• shielding

how does atomic radius impact ionisation energy??

larger the radius, easier to remove electron

how does nuclear charge impact ionisation energy??

the greater the positive charge of the nucleus, the stronger the attraction for the outer electrons

how does shielding impact ionisation energy??

more shells= more shielding= weaker attraction=easier to remove an electron

general trend of ionisation energy down a group eg group 2 (Be-Ba) ??

• larger atomic radius

• so more shielding

• so easier to lose an electron

general trend of ionisation energy across a period eg period 3 (Na-Ar) ??

• mostly increases

• as atomic radii get smaller due to stronger attraction between nucleus and electrons (increase of protons)

• ionisation energy increases as it becomes more difficult to remove the electron

Why do Al and S deviate from this general trend of ionisation energy across period 3??

• Al:

  -moves into higher energy subshell

  -electron easier to remove

  -so has a lower ionisation energy than Mg

• S:

  -new pair of electrons

  -more electron pair repulsion

  -electron easier to remove