The electronic configuration of the elements A and B are 1s², 2s ²,2p⁶,3s² and 1s², 2s²,2p⁵ respectively. The formula of the ionic compound that can be formed between these elements is ___________

The group of elements in which the differentiating electron enters the anti penultimate shell of atoms are called ___________

Period of an element is represented by _____ quantum number

The first list of 23 chemical elements was published by _____ in the year 1789.

In the third period the first ionization potential is of the order.

Define electro negativity.

How would you explain the fact that the second ionisation potential is always higher than first ionisation potential?

Give the general electronic configuration of lanthanides and actinides.

Write the general electronic configuration of s,c ,p, d, and f block elements

Name the first and the last elements in the following periods (n) .
(i) n=:4
(ii) n = 5
(iii) n = 6
(iv) n = 7

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.

Why halogens act as oxidising agents?

Explain classification of elements based on Newland's law of Octaves.

State the findings of modern periodic law.

Explain the diagonal relationship.

Why the first ionisation enthalpy of sodium is lower than that of magnesium while its second ionisation enthalpy is higher than that of magnesium.

State the trends in the variation of electronegativity in group and periods.

Give any five characteristic properties of inner transition elements.