Ionisation Energy Flashcards
Explain the ionisation trends across periods
General trend = increase
2 exceptions:
Aluminium = outer electron is in 3p rather than 3s so is further from nucleus, lower ionisation energy
Sulfur = lower due to electron repulsion
What is the 1st molar ionisation energy equation?
X(g) -> X^+ (g) + e^-
What is the first ionisation energy?
The energy required to remove 1 mole of electrons from 1 mole of gaseous atoms (kj.mol^-1)
What does the 1st molar ionisation energy depend on?
- Nuclear Charge- Shielding- Distance
How does nuclear charge effect I.E.?
As nuclear charge increases so does I.E.
How does shielding effect I.E.?
As shielding increases, I.E. decreases
How does distance effect I.E.?
As distance increases, I.E. decreases
How does I.E. change across a period?
Increases
How does nuclear charge change across a period?
Increases
How does sheilding change across a period?
No change
Why is there an exception between groups 2 and 3?
3 is easier to remove than 2 because of sheilding from the full s orbital
Why is there an exception between groups 5 and 6?
6 is easier to remove than 5 because of electron repulsion between paired electrons
What is a successive I.E.?
The energy required to remove electrons one by one from the same atom
What is the second ionisation energy equation?
X+ (g) -> X^2+ (g) + e^-
What is the general trend in successive I.E.s?
Increase in I.E. because of increasing effective charge on the nucleus because of decreased sheilding, decreased distance and therefore stronger nuclear attraction
