Atomic structure - Ionisation Energies Flashcards
What is first ionisation energy
Energy needed to remove one electron from each atom in one mole of gaseous atoms to for, 1 mol of gaseous 1+ ions
How do your write first ionisation energy
Element =Element+ + e-
What is second ionisation energy
Energy needed to remove 1 electron from each ion in one lobe of gaseous 1+ ions to form 1 mol of gaseous 2+ ions
What are the factors affecting ionisation energy
Nuclear charge
Distance from nucleus
Shielding
How does nuclear charge affect ionisation energy
The higher the nuclear charge the higher the ionisation energy because the greater the positive charge of the nucleus means more attraction between nucleus and outer electrons
How does atomic radius affect ionisation energy
The higher the atom of radius the lower the IE. This is because a higher atomic radius means the outer electrons are further from the nucleus and there is less attraction
How does shielding affect ionisation energy
The more shielding the lower the IE as there is less attraction
What does a high ionisation energy mean
A high attraction between outer electron and nucleus so more energy is needed to remove the electron
How do you write the equation for second ionisation energy
Element + = Element 2* + e-
What is the general formula for IE
X(n-1) = X(n+) + e-
What is the trend in first IE down a group
It decreases
What is the trend for IE along a period
Increase
Why does ionisation energy decrease down group 2
As you go down group 2 each element has an extra electron shell so more shells means more shielding and less attraction as the outer electrons are further away from the nucleus
Why does IE generally increase across period 3
The number of protons increased which means stronger nuclear attraction
Why is there a drop in ionisation energy between Mg and Al in the elements of period 3
Aluminiums outer electron is in 3p orbital rather then 3s and 3p has higher energy than 3s so it is further from the nucleus
