Energy of an electron in the ground state of the hydrogen atom is -2.8 x 10^-18 J. Calculate the ionisation enthalpy of atomic hydrogen in terms of kJ mol^-1.

The electronic configuration of atom is one of the important factor which affects the value of ionisation potential and electron gain enthalpy. Explain.

In what period and group will an element with Z = 118 will be present?

Justify that the fifth period of the periodic table should have 18 elements on the basis of quantum numbers.

Elements a, b, c and d have the following electronic configurations:
a: 1s², 2s², 2p⁶
b: 1s², 2s², 2p⁶, 3s², 3p¹
c: 1s², 2s², 2p⁶, 3s², 3p⁶
d: 1s², 2s², 2p¹
Which elements among these will belong to the same group of periodic table.

Why halogens act as oxidising agents?

Mention any two anomalous properties of second period elements.

Predict the position of the element having an electron configuration(n -1) d¹ ns² for n = 4.

How many elements can be accommodated in the long form of the periodic table? Explain.

Why are noble gases chemically inert?