Ionisation energies Flashcards
What does it mean when an electrons have been removed from an atom or molecule?
It has been ionised.
What is the energy you need to remove the first electron called?
The first ionisation energy.
What is the first ionisation energy?
The first ionisation energy is the energy needed to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions.
How do you write equations for ionisations, e.g. the first ionisation of oxygen?
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What symbol must you use in ionisation equations?
The gas state symbol, because ionisation energies are measured for gaseous atoms.
What should you always refer to rather than a single atom?
1 mole of atoms.
What does the lower the ionisation energy mean?
The easier it is to form a positive ion by removing electrons.
What does a high ionisation energy mean?
There is a high attraction between the electron and the nucleus, so more energy is needed to remove the electron.
What are the three factors which affect ionisation energies?
- Nuclear charge
- Distance from nucleus
- Shielding
How does the nuclear charge affect ionisation energies?
The more protons there are in the nucleus means the more positively charged the nucleus is, causing a stronger attraction for the electrons to the nucleus.
How does distance from the nucleus affect ionisation energies?
Attraction to the nucleus falls very rapidly with distance, so an electron close to the nucleus will be much more strongly attracted than one further away.
How does shielding affect ionisation energies?
As the number of electrons increases, the outer electrons are shielded by the inner electrons (blocked by the electrons) this causes less attraction from the outer electrons to the nucleus
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