The first element of each group, lithium in first group and beryllium in the second group differ from rest of the elements but have similar properties to diagonally situated elements. Lithium resembles with Mg and Be resembles with Aluminium. Boron resembles with Silicon.
The compounds of alkali metals are predominantly ionic. The oxides and hydroxides are soluble in water forming strong alkalies. Important compounds of sodium includes sodium carbonate, sodium chloride, sodium hydroxide and NaHCO₃ Sodium hydroxide is manufactured by Castner-Kellner process and sodium carbonate by Solvay process.
The oxides and hydroxides of group 2 elements are less basic than group 1, oxides and hydroxides. CaO, Ca(OH)₂, \(\mathrm{CaSO}_{4} \cdot \frac{1}{2} \mathrm{H}_{2} \mathrm{O}, \mathrm{CaCO}_{3}\) and cement are industrially important compounds. Portland cement is an important 2 constructional material. It is manufactured by heating limestone and clay in a rotary kiln. The clinker obtained is mixed with 2 to 3% gypsum.
Na⁺,K⁺, Mg²⁺and Ca²⁺ are found in large amounts in biological fluids. These ions perform important biological functions such as maintenance of ion balance and nerve impulse conductions.
(a) What is cause of diagonal relationship?
(b) Why does first element of each group differ from rest of the elements?
(c) Name the product formed at anode and cathode on electrolysis of brine solution
(d) Why is BeSO₄ soluble in water but BaSO₄ in not?
(e) Why is gypsum is added to cement?
(f) What is role of Ca^{2 +} in our body?
(g) What is role of Na⁺ in blood plasma?

Study the table and answer the questions based on the table and related studied concepts.
Atomic and Physical Properties of the Alkaline Earth Metals

(a) Which is best non-radioactive reducing agent in Group 2? Why?
(b) Why does hydration enthalpy of bivalent cations of group 2 decrease down the group?
(c) Which element of group 2 has lowest melting points and why?
(d) Name a radioactive element of group 2
(e) Which group 2 element has lowest density?

Group 1 and group 2 elements are called s-block elements. Their general electronic configuration is ns^{1 to 2}. Group 1 are called alkali metals where as group 2 elements are called alkaline earth metals. They resemble with each other in many respects but differ in some of properties due to difference in valence electrons, electronic configuration and atomic size.
(a) Why are group 1 elements softer than group 2 elements?
(b) Why are group 1 elements more electropositive than group 2?
(c) Why are K, Rb and Cs used in photoelectric cells?
(d) Why is BeCI₂ more covalent than LiCI?
(e) Which colour is imparted to flame by Ca²⁺and Ba²⁺?