s-block elements:
Elements in which last electron enters into s-subshell are called s-block elements. It contains group I elements (Alkali metals) and group II elements (Alkaline earth metals)
1st group elements lose one electron during chemical combination. Therefore its oxidation state is +1.
2nd group elements lose two electrons from valence shell during chemical combination and their oxidation state is +2.
The highest shell number in a sub-shell electronic configuration is the period number of that element.
1. Group number characteristics = no.of electrons in valence sub-shell.
2. s block ionization energy & electro negativity decreases downwards.
3. Metallic character & reactivity increases downwards.
4. Lose electrons during chemical combination j and they form ionic compounds. Their oxides and hydroxides are basic. Their atomic radii are high in a period.
p-block elements:
- Last electron enters into p-subshell.
- Group 13 -18 elements.
- Highly reactive elements are nonmetals – group 17,
- These are elements with positive and negative oxidation state.
Group number of p-block elements = electrons in last p-subshell + 12
d-block elements:
- Last electron enters into penultimate d-subshell
- Known as transition elements.
- Metals
- Shows similarity in group and period.
- Variable oxidation states.
- Form coloured compounds.
Group = electrons in ‘d’-subshdl + electrons in s-subshell.
f-block elements:
- Last electron enters into antepenultimate f sub-shell.
- Contains Lanthanoids and Actinoids.
- Variable oxidation state.
- Most of the Actinoids are radioactive.
- Most of the elements are artificial.
- U, Th, Pu are used in nuclear reactors.
- Some elements are used as catalyst in pet-roleum industry.
