Ionisation Energies Flashcards
What happens when an atom or molecule is ionised?
It becomes charged as electrons have been removed.
Define first ionisation energy.
The first ionisation energy is the energy needed to remove 1 electron from each atom in 1 mole of gaseous atoms to form 1 mole of gaseous 1+ ions.
Why is ionisation an endothermic process?
You have to put energy in tho ionise an atom or molecule.
What is the equation for the first ionisation on oxygen?
O(g) = O+(g) + e-
Explain the nuclear charge factor affecting ionisation energy.
The more protons there are in the nucleus= a more positively charged nucleus= stronger attraction to electrons.
What are 3 factors that affect ionisation energy?
Nuclear charge
Distance from nucleus
Shielding
Explain the distance from the nucleus factor affecting ionisation energy.
Attraction falls off very rapidly with distance. An electron close to the nucleus will be much more strongly attached than one further away.
Explain the shielding factor affecting ionisation energy.
As the number of electrons between the other electrons and the nucleus increases, the outer electrons feel less attraction towards the nuclear charge. This lessening of the pull of the nucleus by inner shells of electrons is called shielding.
What is the second ionisation energy?
The energy needed to remove 1 electron from each ion in 1 mole of gaseous 1+ ions to form 1 mole of gaseous 2+ ions.
What is the equation for the second ionisation of oxygen?
O+(g) = O2+(g) + e-
Explain why the ionisation energies show a general increase in period 2 (Li to Ne).
The nuclear charge of the atoms increases so electrons experience greater attraction whilst the electrons stay in the same shell with similar shielding.
