Question

Among the elements $Ca, Mg, P$ and $Cl$, the order of increasing atomic radii is -

• A. Cl < P < Mg < Ca
• B. P < Cl < Ca < Mg
• C. Ca < Mg < P < Cl
• D. Mg < Ca < Cl < P

Answer 1

The Correct Option is A

 To determine the order of increasing atomic radii among the elements Cl, P, Mg, and Ca, we need to understand the trends in atomic radii across the periodic table.

1. Atomic radius generally decreases across a period from left to right. This is because, across a period, protons and electrons are added, increasing the nuclear charge, which pulls the electrons closer to the nucleus.
2. Conversely, atomic radius generally increases down a group. As you move down a group, new electron shells are added, which increases the size of the atom.
3. Given that:
   • Chlorine (Cl) and Phosphorus (P) are in the same period (Period 3), with Cl to the right of P.
   • Magnesium (Mg) and Calcium (Ca) are in the same group (Group 2), with Ca below Mg.
4. The atomic radius order of these elements will be:
   • Cl has the smallest atomic radius since it is to the right of P in the same period.
   • P has a larger atomic radius than Cl, but smaller than Mg or Ca.
   • Mg has a smaller atomic radius than Ca because it is above Ca in the same group.
   • Ca has the largest atomic radius among them, being below Mg.

Thus, the order of increasing atomic radii is: Cl < P < Mg < Ca.

Element	Atomic Radius (approximate in picometers)
Cl	99
P	110
Mg	160
Ca	197

The correct option is: Cl < P < Mg < Ca.