Ionisation Energy Flashcards
What is the definition of first ionisation energy?
The energy required to remove 1 electron from each atom of 1 mole of gaseous atoms (to form 1 mole of gaseous +1 ions)
What happens to ionisation energy down a group?
Nuclear charge increases Electron shells increases Electron shielding increases Atomic radius increases Overall nuclear attraction decreases First ionisation energy decreases
What happens to ionisation energy across a period?
Nuclear charge increases electron shells stay the same Electron shielding stays the same Atomic radius decreases slightly Overall nuclear attraction increases First ionisation energy increases
What are the anomalies to the “going across a period” rule?
Group 2 to 3
Group 5 to 6
How does a pair of electrons affect the first ionisation energy?
A pair of electrons increase repulsion, which decreases nuclear attraction so it is easier to lose the electron, lower first ionisation energy
What is the definition of second ionisation energy?
The energy required to remove 1 electron from each ion of 1 mole of gaseous ions (to from one mole of gaseous +2 ions)
How does the number of electrons removed and the energy needed relate?
The more electrons that are removed, the higher the energy that is needed
How can we tell the group number from the ionisation energy?
The group number can be determined where there is a sudden rise in energy.
(e.g. if the energy jumps suddenly between 4 and 5, the group number is 4)
Why does it take more energy to remove the next electron?
It feels greater effective nuclear charge so it is attracted to the nucleus more
What does the large jump in energy indicate?
That the electrons are being removed from a shell closer to the nucleus
What are the things to include in the reasoning behind an increase or decrease in ionisation energy?
Nuclear Charge Atomic Radius Electron Shielding Nuclear Attraction Ionisation energy
