Question

given below are a few elements of the modern periodic table. the atomic number of the element is given in the parenthesis a[4],b[9],c[14],d[19],e[20] select the elements that has one electron in the outermost shell. also, write the electronic configuration of this element. which two elements amongst these, belong to the same group give the reason for your answer. which two elements amongst these belong to the same period? which one of the two has a bigger atomic radius?

Answer 1

Answer: The answer to the questions are

1. d, electronic configuration: 1s2, 2s2, 2p6, 3s2, 3p6,  4s1

2. a and e because they have the same number of valence electrons.

3. a and b because they have the same number of shells of electrons.

4. a because atomic radius decreases across the period.

Explanation:

Answer 2

Answer-
Element D has one electron in the outermost shell.
Electronic Configuration of D - 2,8,8,1
Elements A and E belong to the same group because both of them have the same number of valence electrons I.e. 2.
Elements A and B belong to the same period. Out of the two, element A has a bigger atomic radius because the size of the atom decreases when we move from left to right along a period.