Ionisation Energy Flashcards
Define first ionisation energy.
The first ionisation energy of an element is the energy required to remove one electron from one atom of one mole of gaseous atoms.
What is the equation for first ionisation energy.
M(g) - M+(g) + e-(g)
Where m is any element
What is the equation for 2nd , 3rd and 4th ionisation energies?
M+(g) - m2+(g) + e-
M2+(g) - m3+(g) +e-
Why do successive ionisation energies increase ?
There is a shorter distance from the nucleus so the further away from the nucleus the lower the ionisation energy.
More electrons are removed so there is less repulsion between the electrons in the resulting ion. The electrons are therefore more stable and are harder to remove.
What are 4 factors that affect ionisation energy and how ?
Distance from the nucleus
Nuclear charge - more nuclear charge means more ionisation is needed to remove an electron.
Shielding - more energy levels reduced the electrostatic force of attraction between the nucleus and outer electron.
Electron repulsion
What do large jumps in ionisation energy suggest ?
Electrons are being removed from the next principal energy level.
Why is thr first ionisation energy of magnesium higher than that of sodium ?
Magnesium has a stronger nuclear charge as it has one more proton but the same number of electrons so the electrons are more strongly attached.
Explain why the first ionisation energy of neon is higher than that of Sodium.
Neon has an electron removed from the 2p orbital which is closer to the nucleus than the 3s of sodium so the electrons are more strongly attached to the nucleus.
Why is the first ionisation energy of neon lower than the third ionisation energy of magnesium.
Magnesium is a smaller atom and has a higher nuclear charge as it has 2 more protons.
State the general trend of ionisation energies in group 3 elements.
They have increasing ionisation energies as a potion is gained in each nucleus creating a greater nuclear charge.
Why are ionisation energies often lower than expected ?
An electron is being removed from the next principal energy level which is further away from the nucleus and therefore has less electrostatics attraction.
Why are second ionisation energies often harder to remove electrons on.
You begin with a greater nucleus charge.
M+(g)
Explain why the first ionisation energies increase from Na to Ar.
The ionisation energy increases as the nuclear charge increase by one each time therefore there is a stronger attraction between the nucleus and outer electron.
How and why do Al and S differ from the trans of first ionisation energies ?
The outer electron is removed from the 3P sub level which has better shielding than the 3S and therefore more energy is needed.
S has an electron removed from the 3P with an electron pair. The repulsion between the pair means that less ionisation energy is required.
