Flashcards
First Ionisation Energy
Flashcards do conjunto (13)
- 1Define first ionisation energyThe energy needed to remove 1 mole of electrons from 1 mole of gaseous atoms to form 1 mole of gaseous 1+ ions
- 2TRUE OR FALSE: Ionisation is an endothermic processTRUE
You have to put energy in to ionise an atom or molecule, so it's an endothermic process - 3What are the 3 factors affecting ionisation energy?Nuclear charge
Atomic radius
Shielding - 4How does nuclear charge affect ionisation energy?The more protons there are in the nucleus, the more positively charged the nucleus is and the stronger the attraction for the electrons
- 5What happens to the ionisation energy when nuclear charge increases?Ionisation energy increases
- 6How does atomic radius affect ionisation energy?Attraction falls off very rapidly with distance. An electron close to the nucleus will be much more strongly attracted than one further away
- 7What happens to ionisation energy when atomic radius increases?Ionisation energy decreases
- 8How does shielding affect ionisation energy?As the number of shells between the outer electrons and the nucleus increases, the outer electrons feel less attraction towards the nucleus
- 9What happens to ionisation energy when shielding increases?Ionisation energy decreases
- 10Describe and explain the trend in ionisation energy down the groupAs you go down a group, ionisation energies generally fall (less energy is needed to remove outer electrons). This is because:
Shielding increases
Atomic radius increases
Nuclear charge increases (BUT! Effect is overridden by the effect of the extra shells) - 11Describe and explain the trend in ionisation energy across a periodAs you move across a period, the ionisation energies generally increase. This is because:
Shielding stays the same
Atomic radius decreases
Nuclear charge increases
HOWEVER! There are small drops between Groups 2 and 3, and 5 and 6 - 12The ionisation energies across a period generally increase. However, there is a small drop between Groups 2 and 3. Why?The drop between Groups 2 and 3 are due to the outer electrons in Group 3 elements being in a p-orbital rather than an s-orbital. The p-orbital has a slightly higher energy than the s-orbital, so the electron is found (on average) further from the nucleus. The p-orbital also has additional shielding provided by the s-orbital electrons. Both of these factors together are strong enough to override the effect of the increased nuclear charge, so IE drops slightly.
- 13The ionisation energies across a period generally increase. However, there is a small drop between Groups 5 and 6. Why?The drop between Groups 5 and 6 is due to electron repulsion. For example:
P: [Ne] 3s² 3p³
S: [Ne] 3s² 3p⁴
The shielding is identical and the electrons are being removed from the 3p sub-shell.
In P's case, the electron is being removed from a singly-occupied orbital. But in S, the electron is being removed from an orbital containing two electrons. The repulsion between two electrons in an orbital means that electrons are easier to remove from shared orbitals (full>half>partial)
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- O usuário eliminou as informações de disciplina FlashCards sobre First Ionisation Energy, criado por Usuário eliminado em 05-03-2018.
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- Usuário eliminado · mar 2018
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- 5 mar 2018
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- Criado por Yinka F · 3 mar 2018
- Copiado por Yinka F · 5 mar 2018
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