S – Block
(Group IA Elements)
Group I A Elements:
Hydrogen (Atomic number-1)
Lithium (Atomic number-3)
Sodium (Atomic number-11)
Potassium (Atomic number-19)
Rubidium (Atomic number-37)
Strontium (Atomic number-55)
- Elements of group IA and IIA are known as s – block elements.
- Except Hydrogen all elements are metals.
- Group IA consists of Hydrogen, Lithium, Sodium, Potassium, Rubidium, Cesium, Francium.
- Group IIA consists of Beryllium, Magnesium, Calcium, Stratium, Barium, Radium.
- IA elements (except Hydrogen) – Alkali metals.
- IIA Elements Alkaline earth metals.
- Have one electron in the outermost orbit.
- By loosing the electron they form stable + 1 ion.
- They are univalent and show + 1 oxidation state.
General periodic trends:
- As we move from up to down the atomic radius increases.
- Order of radius size = H < Li < Na < Rb < Cs < Fr
- Ionization potential coming from top to bottom decreases.
- Density generally increases with an increase in atomic mass.
- Exception Potassium is expected to have more density than sodium but actually has less than sodium.
- Electronegativity from top to bottom decreases.
- Alkali metals along their individual periods have largest atomic radius.
- Mobility of ions increases down the group
is the order of mobility of ions.
- Hydration enthalpy decreases down the group.
Ø Heating effects of carbonates of IA elements.
Ø All metal carbonates of IA except have no effect on heating.
Ø Heating effect of nitrates of IA elements.
Flame Test :