7:Ionisation energy Flashcards
Definition of first ionisation energy
The first ionisation energy of an element is the energy needed to remove one electron from each atom in a mole of gaseous atoms of an element.
Write the equation for the first ionisation energy of any element X
X(g) → X†(g) + e‾
What is nuclear charge
The positive charge of the nucleus.
The higher the nuclear charge the more strongly the electrons will be attracted to the nucleus.
What is atomic radius
The average distance of the outermost electrons from the nucleus
What is shielding
Electrons being repelled by other electrons in inner shells.
What is the general trend of first ionisation energy across a period
The overall trend is that the first ionisation energy increases but there are 2 exceptions.
Why does the first ionisation energy increase across the period
The nuclear charge increases and shielding does not change very much
Why does 1st IE decrease between group 2 and 3
The highest energy electron is in a higher energy subshell so it is slightly easier to remove
Why does the 1st IE decrease between group 5 and 6
The highest energy electron is paired so it is being repulsed by the other electron so it is easier to remove
What is trend for successive ionisation energies of the same element
Ionisation energy increases and there are big jumps when the electron shell changes.
Why do successive ionisation energies always increase.
As the number of electrons decreases, there is less repulsion between them so the can move closer in, where the attraction to the nucleus is greater.
Why are there big jumps in IE at shell changes in successive ionisations
Because the electron removed is closer to the nucleus so is much more strongly attracted to the nucleus.
