Answer and explanation;
An element block is a set of elements located in adjacent element groups.
There are four blocks; s, p, d, f; which originated from descriptions of spectroscopic lines of atomic orbitals: sharp, principal, diffuse and fundamental.
s-block; the first two groups of the periodic table, the s-block metals:
- are either alkali metals or alkaline earth metals
- are soft and have low melting points
- are electropositive and chemically active
P-block elements include the last six element groups of the periodic table, excluding helium. The p-block elements include all of the nonmetals except for hydrogen and helium, the semi-metals, and the post-transition metals.
D-block elements are transition metals of element groups 3-12. D-Block elements:
- have valence electrons in their two outermost and shells
- 'd' block elements behave in a manner that is somewhere between that of highly reactive electropositive alkali metals and the covalent compound forming elements.
- have high melting and boiling points
- usually form colored salts
- are generally good catalysts
f-block; Inner transition elements, usually the lanthanide and actinide series, including lanthanum and actinium. These elements are metals which have:
- high melting points
- variable oxidations states
- the ability to form colored salts
Uniqueness of group D elements; Normally across the period atomic radii should decrease. But d-block elements do not follow this trend. It increases From V to Cr and them remains constant and decreases and remains constant again.