Question

The position of 8 elements in the Modern Periodic table is given below.

Period No:

2 Li(3) Be(4)

3 Na (11) Mg (12)

4 K (19) Ca(20)

5 Rb (37) Sr(38)

The atomic numbers of the elements are given in the parenthesis. Analyse

the period, group and Atomic number of the elements and answer the

following question.

(i) Predict the number of valence electrons in Rb.

(ii) What is the number of shells in Sr.

(iii) Predict whether K is a metal or a non-metal with reason.

(iv) Which of these elements will have largest atomic size?

(v) Arrange Be, Ca, Mg and Rb in the increasing order of metallic character.​

Answer 1

Answer:

The position of eight elements in the Modern Periodic Table is given below where atomic numbers of elements are given in the parenthesis.

Period No

2 Li(3) Be(4)

3. Na(11) Mg(12)

4. k(19) Ca (20)

5. Rb(37) Sr(38)

i) Write the electronic configuration of Ca

ii) Predict the number of valence electrons in Rb

iii) What is the number of shells in Sr?

iv) Predict whether k is a metal or a non-metal.

v) Which one of these elements has the largest atom in size?

vi) Arrange Be,Ca,Mg and Rb in the increasing order of the size of their respective atoms.

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ANSWER

Electronic configuration of Ca-2,8,8,2

i) Valence electrons in Rb is 1.

ii) Five

iv) Metal

v) Rb is biggest in size.

vi) Be < Mg < Ca < Rb