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Question

Give the correct symbol for an element or ion that fits each other following descriptions.

[J] = noble gas e- configuration

a. a transition metal w/ 5(n-1)d electrons ____Y____

b. the smallest atom in the 5th period ____Xe_______

c. diatomic element in the 4th period _____Br_______

d. an element with configuration [J]ns^2 np^5 ___I______

e. an element with configuration [ J] (n-2)f^14 (n-1)d^10 ns^2 np^2 ____Pb_______

f. a cation isoelectronic with Kr ____Ca_________

g. an anion larger than Br- _______Br_____

h. the most reactive metal _______Fr_______

could you guys please check my answer to see if they are correct.? please let me know which one is wrong and why it is wrong because i want to learn from it.

thanks

Answer 1

a) Please pick an appropriate n.  Here n must be greater than 2 (that would have d orbitals) and less then 4 (there are a max of 10 d electrons.  Hence n = 3, and 5(n-1) = 10. The element is Zn.

d) I would not pick I, since there are also d-electrons in I.  One example is as shown in (e).  I would pick Ar.

f) Please understand the problem.  Ca has 16 electrons LESS than Kr.  The right answer is Rb+ or Sr(2+)

g) "Br" is neither an anion nor larger than Br-.  The right answer is I-.

The others are correct.