Question

An ion has 18 electrons in the outermost shell, it is
(a) Cu⁺
(b) Th⁴⁺
(c) Cs⁺
(d) K⁺

Answer 1

Answer:

The correct answer is Cu+.

Explanation:

Atomic number of copper Cu is 29.  

Electronic configuration of copper = 2, 8, 18 , 1

When copper loses one electron then it becomes a positive ion that is Cu+.

No of electrons in ionic Cu+ = atomic no. of copper - no. of electrons lost

                                         = 29 - 1 = 28

Therefore electronic configuration of copper ion Cu+ 2,8,18.

This means that Cu+ has 18 electrons in its outermost shell.  

Answer 2

Answer:

it is (a) Cu⁺ (b) Th⁴ ... Atomic number of copper Cu is 29. When copper loses one electron then it becomes a positive ion that is Cu+. Therefore electronic configuration of copper ion Cu+ 2,8,18. This means that Cu+ has 18 electrons in its outermost shell.