Class 11 NEET Chemistry Classification Of Elements And Periodicity In Properties

Both Ga and Cs have low melting points.

Element	Melting point/K
Ga	303
Cs	302

- On Pauling scale, the electronegativity value of N and Cl have same (3.0).
- ‌‌Ar,K+,Cl−,Ca2+ and S2− have 18 electrons. So these are isoelectronic species.
- The correct order of first ionization enthalpy is Si>Mg>Al>Na
First ionisation enthalpy of Mg is higher than Al because the penetration of a 3 s -electron to the nucleus is more than that of a 2p-electron.
- Generally down the group atomic radii increases

Atom	Atomic radius/pm
Li	152
Rb	244
CS	262