Topic 1.1.4 - Ionisation energies Flashcards
Where does evidence for energy levels in atoms come from?
The emission spectra
How does the emission spectra provide evidence for energy levels in atoms?
When atoms in a gaseous state are given energy by heating, the electrons move to higher energy levels. Eventually they move back to their original energy level, emitting electromagnetic radiation.
What is ionisation energy?
The energy required to remove an electron from each atom of an element in one mole of atoms in the gaseous state.
What does the first ionisation of an element result im?
A positive ion and an electron
Why is the first ionisation energy lower than second?
The first electron is furthest away from the nucleus meaning it doesn’t experience as much attractive force.
How does the orbital an electron is in affect the ionisation energy?
If an electron is in a high energy orbital e.g 3d then less energy will be required to remove it
Factors that affect ionisation energy
the orbital electron is in
nuclear charge
repulsion experienced from other electrons
Why does ionisation increase across a period?
Nuclear charge increases meaning there is more attraction between nucleus and electrons.
Why does ionisation energy decrease down a group?
Because for every element, a new quantum shell is added meaning electrons in it will have higher energy so less required to remove it.
due to the shielding or screen effect of the outer electrons from the nucleus and so the attraction is weaker and they are more easily removed.
