1.1 Atomic Structure (Ionisation Energies)
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What is the definition of first ionisation energy?
Energy required to remove 1 electron from a mole of gaseous atoms to give 1 mole of gaseous ions with a charge of +1
What type of reaction is ionisation?
Endothermic
What is Hie (Enthalpy of ionisation)?
The amount of energy required to ionise
What is the definition of second ionisation energy?
Energy required to remove 1 electron from 1 mole of gaseous +1 ions to give 1 mole of gaseous ions with a charge of +2
What is the difference between first and second ionisation energy in terms of energy required?
The second ionisation requires more energy
What effects ionisation energy?
P- proton number increase/decrease A- Attraction between nucleus and outer electron increase/decreasing D- Distance between nucleus and outer electron increase/decreasing S- Shielding between nucleus and outer electron increase/decreasing
Why does atomic radii decrease across periods?
• Proton number increases • Shielding remains the same • Attraction is felt more strongly so radii decreases
Why is caesium more easily ionised than lithium?
• Proton number increases • Shielding increases • Increased distance from nucleus • Attraction is not as strong
What is the general rule for 1st ionisation energy?
• increases across a period
Why does 1st ionisation energy increase across a period?
• Protons increase • Increase in shielding is negligible • More energy required to remove outer electron
What exceptions are there to the first ionisation rule?
Groups 2-3 as removing electron p subshell has a higher energy than s subshell so it is more easily removed Groups 5-6 electrons in sub shells now need to pair up and negative electrons repel eachother
What is the general equation for the 1st ionisation process?
• X -> X^1+ + e-
When given a successive ionisation energy how can you tell which group it is in?
Looking at the time before there is a large increase
Why in successive ionisation energies is there a large leap in ionisation energies?
Gone down a shell so less shielding and a smaller distance between nucleus and electron so attraction is stronger and requires more energy to overcome