Question

The atomic radii of three elements A,B,C of periodic table are 186 pm ,104 pm, and 143 pm respectively.giving a reason , arrange these elements in the increasing order of atomic number in the period .

Answer 1

A, C, B. Because A have largest size therefor it will come first and as atomic size goes on decresing for left to right in period due to increase in effective nuclear charge.

Answer 2

the element A has the more atomic size .i.e. 186 pm and element B has atomic size 143 pm. i.e. less than element A and element C has atomic size less than element A and B.
Here, if the atomic radius increases, then it means, the shells are increasing. But, when the electrons in the atom increases, then only the shells will increase. We know, the no. of electrons in an atom is called as the atomic number.
therefore, the atomic radius increases with the increase in the no. of shells and electrons.
so, the atom with more atomic radius has more atomic number