Question 3: [Physical > Atomic Structure]
Use of the Data Booklet is relevant to this question.
In the gas phase, aluminium and a transition element require the same amount of energy to form one mole of an ion with a 2+ charge.
What is the transition element?
A Co
B Cr
C Cu
D Ni
Reference: Past Exam Paper – November 2002 Paper 1 Q3
Solution 3:
Answer: A.
For aluminium to form an ion with a 2+ charge we must add its 1st ionisation energy, to remove one electron and gain 1 positive charge, with its 2nd ionisation energy, to remove another electron from the 1+ aluminium ion to make it a 2+ ion. This total energy, according to the data booklet, is 577 + 1820 = 2397. Thus we have to find a transition element that has the same total energy required for removing 2 electrons.
A Co: 757 + 1640 = 2397
B Cr: 653 + 1590 = 2243
C Cu: 745 + 1960 = 2705
D Ni: 736 + 1750 = 2486
As you can see Co is the only exact match thus is the A is the correct answer.
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