↻

Successive Ionisation Energies - identifying an element's group.

A complete table of successive ionisation energies of the elements hydrogen to calcium can be found here.

Successive ionisation energies for Carbon (6C) 1s2 2s2 2p2.

Ionisation NumberEquationIonisation Energy (kJmol-1)
IE1C (g) →  C+ (g) + e–1 086
IE2C+ (g) →  C2+ (g) + e–2 353
IE3C2+ (g) →  C3+ (g) + e–4 620
IE4C3+ (g) →  C4+ (g) + e–6 223
IE5C4+ (g) →  C5+ (g) + e–37 831
IE6C5+ (g) →  C6+ (g) + e–47 277

There is a very large jump in ionisation energy moving from IE4 to IE5.
This is because the 5th electron is coming out of a shell that is full and nearer to the nucleus.
Also, there is one less inner shell and so less shielding.
The electron is much more strongly attracted to the nucleus and it takes much more energy to remove.

 Element IE1 IE2 IE3 IE4 IE5 IE6 IE7 IE8IE9
Na4964 560       
Mg7381 4507 730      
Al5771 8162 74411 600     
Si7861 5773 2284 35416 100    
P1 0601 8902 9054 9506 27021 200   
S9992 2603 3754 5656 9509 36027 100  
Cl1 2562 2953 8505 1606 5609 36011 00033 500 
Ar1 5202 6653 9455 7707 2308 78012 00013 80040 760

As can be seen from the table above, it is possible to identify an element’s group from its successive ionisation energies. 
When there is an exceptional jump in ionisation energy, that particular electron is coming out of a new shell.
So for example, if the exceptional jump comes between IE6 and IE7, the element is in Group 6.

Complete the graph opposite of the successive ionisation energies of Na.
Note: no need to distinguish between sublevels.

Na (g) → Na+ (g) + e–

Na+ (g) → Na2+ (g) + e–

Na2+ (g) → Na3+ (g) + e–

Na3+ (g) → Na4+ (g) + e–

Na4+ (g) → Na5+ (g) + e–

Na5+ (g) → Na6+ (g) + e–

Click here for the solution.

Find the groups that elements 1 - 6 belong to below.

 Element IE1 IE2 IE3 IE4 IE5 IE6 IE7 IE8
17621 5403 3004 3908 12011 90014 90018 200
24183 0704 6006 4808 12010 70012 30014 600
32 0803 9506 1509 29012 10015 20019 50023 000
47361 4507 74010 50013 60018 00021 70025 600
55771 8202 74011 60014 80018 400 23 40027 500
61 3103 3905 3207 45011  00013 30071 00084 100

Answers are here.                    Find a table of successive IEs for atoms H  ⇒  Ca here.

Scroll to Top