The atomic number of an element is 19.
(a) Write the electronic configuration of the element and determine (i) the valency of the element and (ii) whether the element is a metal or non-metal.
(b) Write the formula of the oxide of the element.
(c) Is the element more reactive or less reactive than Na (atomic number 11). Justify your answer giving example.

Explanation

(a) The element with atomic number 19 is potassium (K). Its electronic configuration is 2, 8, 8, 1.
(i) Element is monovalent (ii) Element is a metal.
(b) Formula of the oxide of the element : `K_(2)O`
(c) The element K (Z = 19) is more reactive than the element Na (Z = 11). Actually, K is placed below Na in group 1 (Alkali metals) and the reactivity increases down a group. For example, both Na and K catch fire in water but K burns more violently than Na.