Ionisation Energy
- Created by: Kb_1504
- Created on: 16-11-15 15:02
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- Ionisation Energy
- Ionisation is all about removing electrons from atoms to make positive ions
- The first ionisation energy is the energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions
- M(g)>M+(g)+e-
- The second ionisation energy refers to the removal of the next mole of electrons from the mole of gaseous 1+ ions:
- M+(g)>M2+(g)+e-
- The third ionisation energy refers to M2+(g)>M3+(g)+e-, and so on.
- Factors influencing the first energy
- Nuclear Charge
- The amount of Protons in the nucleus. The larger the number, the larger the charge
- Nuclear Atrraction
- The distance between the electron and the nucleus. the closer the electron, the bigger the attraction
- These fatcs mean that the ionisation energy
- decreases down a group because the atomic radius and electron shielding both increase.
- increases across a period
- These fatcs mean that the ionisation energy
- decreases down a group because the atomic radius and electron shielding both increase.
- increases across a period
- Nuclear Atrraction
- The distance between the electron and the nucleus. the closer the electron, the bigger the attraction
- Electron Sheilding
- The more shells away, the less nuclear attraction. for example, the outer shell electron for potassium is more shielded that that of the outer electron of a sodium electron since there are more shells between the electron and nucleus
- Nuclear Charge
- The amount of Protons in the nucleus. The larger the number, the larger the charge
- Nuclear Charge
- Ionisation energies across a period
- The overall trend is a general increase across the period.
- This is caused by the increasing nuclear charge attracting the electrons more strongly and therefore making it difficult to remove an electron.
- The outer electrons of these elements are in the same shell, so atomic radius and electron shielding remain similar across the period.
- This is caused by the increasing nuclear charge attracting the electrons more strongly and therefore making it difficult to remove an electron.
- The overall trend is a general increase across the period.
- Ionisation energies down a group
- As we go down a group, th efirst ioniastion energy decreases
- This is because for each successive element, the distance from the nucleus and electron shielding from inner electrons both increase, and these outweight the effect of increasing nuclear charge
- As we go down a group, th efirst ioniastion energy decreases
- How to predict electron configurations from ionisation energies
- The values of successive ionisation energies can tell us the group an element is from. Successive ionisation energies (IE) simply mean thfirst, second, third, etc. IE for one particular element.
- We can se that the pattern for successive IEs is: all group 1 elements is 1 low IE. All group 2 elements is 2 low IEs. All group 3 elements is low 3 IEs
- The values of successive ionisation energies can tell us the group an element is from. Successive ionisation energies (IE) simply mean thfirst, second, third, etc. IE for one particular element.
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