Question

Two elements A and B have 3 and 4 shells respectively and the ratio of valence electrons is 1: 2. When these two metals are dropped in water in separate containers, what observations do you find? Justify your observation and write periodic property.

Answer 1

A has 3 shells⇒ Na ( 1 valence electron) $\left[Ne\right]3s^1$

B has 4 shells⇒ Ca (2 valence electrons) $\left[Ne\right]3s^{2}3p^{6}4s^2$

Na in water, sodium hydroxide is formed. Hydrogen gas is formed as a bi- product that gets burnt with a bright flame…. making the reaction highly exothermic.

Ca with water, the calcium metal begins to bubble vigorously as it reacts with water, producing hydrogen gas and a cloudy white precipitate of $Ca(OH{)}_2$, calcium hydroxide

$2Na+2H_{2}O⟶2NaOH+H_2$

$Ca+2H_{2}O⟶Ca(OH{)}_2+H_2$