Ionisation energies help please!! Aqa as level
hi can someone please explain to me in detail what ionisation energies are, trends across period 1-4 in the table and why the energy increases down the groups and decreases across the period please! I'm very confused
Thank you so much!
Thank you so much!
Original post by kandykissesxox
hi can someone please explain to me in detail what ionisation energies are, trends across period 1-4 in the table and why the energy increases down the groups and decreases across the period please! I'm very confused
Thank you so much!
Thank you so much!
you have your basic facts incorrect.
It is the energy required to remove 1 electron from each of one mole of gaseous atoms forming 1 mole of gaseous ions.
It is represented by the equation:
M(g) --> M+(g) + 1e
It decreases down a group with increasing shielding
It generally increases across a period BUT there is a periodic pattern with two drops between groups 2&3 and 5&6
Check this interactive link out ionisation energy (click on the points for more info)
(edited 9 years ago)
When you take electrons off an atom, it becomes an ion because it has less electrons than protons - this is ionisation. (first) ionisation energy is simply the energy required to knock off one electron from an atom (though the definition is more specific with gaseous moles). You "knock off" electron/s from the furthest shell.
Each atom/ion contains a positive nucleus - where the protons are stored. Therefore, electrons surrounding the nucleus will have differing levels of electrostatic attraction to this positive nucleus - the furthest electrons have a weaker attraction than nearest electrons since the distance is greater.
As you go down a group, the shells (or energy levels) increase. This means the attraction between furthest electron and nucleus is weaker. It is therefore easier to remove because there is less of an attraction between the electron and nucleus - therefore ionisation energies decrease down a group - not increase as you have said.
As you go across a period, the amount of shells remains fixed. However, the number of protons in the nucleus is increasing. This enables the nucleus to "pull" the furthest shell nearer, increasing the attraction between furthest electrons and nucleus. It is therefore harder to remove electrons and so the (first) ionisation energy increases.
If you want, I can explain why there are some dips in trends too
Each atom/ion contains a positive nucleus - where the protons are stored. Therefore, electrons surrounding the nucleus will have differing levels of electrostatic attraction to this positive nucleus - the furthest electrons have a weaker attraction than nearest electrons since the distance is greater.
As you go down a group, the shells (or energy levels) increase. This means the attraction between furthest electron and nucleus is weaker. It is therefore easier to remove because there is less of an attraction between the electron and nucleus - therefore ionisation energies decrease down a group - not increase as you have said.
As you go across a period, the amount of shells remains fixed. However, the number of protons in the nucleus is increasing. This enables the nucleus to "pull" the furthest shell nearer, increasing the attraction between furthest electrons and nucleus. It is therefore harder to remove electrons and so the (first) ionisation energy increases.
If you want, I can explain why there are some dips in trends too
Original post by Dylann
When you take electrons off an atom, it becomes an ion because it has less electrons than protons - this is ionisation. (first) ionisation energy is simply the energy required to knock off one electron from an atom (though the definition is more specific with gaseous moles). You "knock off" electron/s from the furthest shell.
Each atom/ion contains a positive nucleus - where the protons are stored. Therefore, electrons surrounding the nucleus will have differing levels of electrostatic attraction to this positive nucleus - the furthest electrons have a weaker attraction than nearest electrons since the distance is greater.
As you go down a group, the shells (or energy levels) increase. This means the attraction between furthest electron and nucleus is weaker. It is therefore easier to remove because there is less of an attraction between the electron and nucleus - therefore ionisation energies decrease down a group - not increase as you have said.
As you go across a period, the amount of shells remains fixed. However, the number of protons in the nucleus is increasing. This enables the nucleus to "pull" the furthest shell nearer, increasing the attraction between furthest electrons and nucleus. It is therefore harder to remove electrons and so the (first) ionisation energy increases.
If you want, I can explain why there are some dips in trends too
Each atom/ion contains a positive nucleus - where the protons are stored. Therefore, electrons surrounding the nucleus will have differing levels of electrostatic attraction to this positive nucleus - the furthest electrons have a weaker attraction than nearest electrons since the distance is greater.
As you go down a group, the shells (or energy levels) increase. This means the attraction between furthest electron and nucleus is weaker. It is therefore easier to remove because there is less of an attraction between the electron and nucleus - therefore ionisation energies decrease down a group - not increase as you have said.
As you go across a period, the amount of shells remains fixed. However, the number of protons in the nucleus is increasing. This enables the nucleus to "pull" the furthest shell nearer, increasing the attraction between furthest electrons and nucleus. It is therefore harder to remove electrons and so the (first) ionisation energy increases.
If you want, I can explain why there are some dips in trends too
Hi thank you so much for taking the time to explain, I'm still unsure as to why the number of electron shells remain the same. And yes please!!
Original post by charco
you have your basic facts incorrect.
It is the energy required to remove 1 electron from each of one mole of gaseous atoms forming 1 mole of gaseous ions.
It is represented by the equation:
M(g) --> M+(g) + 1e
It decreases down a group with increasing shielding
It generally increases across a period BUT there is a periodic pattern with two drops between groups 2&3 and 5&6
Check this interactive link out ionisation energy (click on the points for more info)
It is the energy required to remove 1 electron from each of one mole of gaseous atoms forming 1 mole of gaseous ions.
It is represented by the equation:
M(g) --> M+(g) + 1e
It decreases down a group with increasing shielding
It generally increases across a period BUT there is a periodic pattern with two drops between groups 2&3 and 5&6
Check this interactive link out ionisation energy (click on the points for more info)
Thanks a lot!!
The link you sent has really helped my understanding(edited 9 years ago)
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