Question

Arrange the following elements in the order of decreasing size
(a) Na (b) Mg (c) K (d) Ca​

Answer 1

Answer:

K > Ca > Na > Mg

Concept used:

First let's understand the concept used:

★ Atomic size increases as we go down the group because the number of shells of atoms increases due to increase in atomic number.

★ Atomic size decreases as we go across a period because of the increase in nuclear charge

Explanation:

• Potassium is placed to the extreme left and is below Sodium. So it has maximum atomic size.
• Next comes the Calcium which is just next to Potassium and has a slightly less atomic size than Potassium.
• Moving on to previous period, Sodium has more atomic size since it is placed in the left and then comes Magnesium.