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)
Francium (Atomic number – 87)
- Elements of group I A and II A 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.
- II A 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.
∴ Rb⁺ > K⁺ > Na⁺ > Li⁺ > H⁺ is the order of mobility of ions.
- Hydration enthalpy decreases down the group.
∴ H⁺ > Li⁺ > Na⁺ > K⁺ > Rb⁺ in case of hydration enthalpy.
⇒ Heating effects of carbonates of IA elements.
(M = Na, K, Rb, Cs), (Exception Li₂CO₃ → Li₂O + CO₂)
⇒ All metal carbonates of IA except Li₂CO₃ have no effect on heating.
⇒ Heating effect of nitrates of IA elements.
(M = Na, K, Rb, Cs), (LiNO₃ → Li₂O + NO₂)
Li → Crimson Red
K → Violet
Rb → Red Violet
Cs → Blue