The atomic number of an element is 16. Predict (i) the number of valence electrons in its atom (ii) its valency (iii) its group number (iv) whether it is a metal or a non-metal (v) the nature of oxide formed by it (vi) the formula of its chloride

For an element with atomic number 16 (Sulphur, $S$):

(i) Number of valence electrons: The electronic configuration is $2, 8, 6$. Therefore, it has 6 valence electrons.

(ii) Valency: It needs 2 electrons to complete its octet ($8 - 6 = 2$). Its valency is 2.

(iii) Group number: For elements with more than 2 valence electrons, Group No. = $10 + \text{valence electrons} = 10 + 6 =$ 16.

(iv) Metal or Non-metal: Since it has 6 valence electrons and belongs to group 16, it is a non-metal.

(v) Nature of oxide: Non-metals form acidic oxides. As seen in the text (Activity 1.5), sulphur forms oxides like $SO_2$ and $SO_3$, which are acidic in nature.

(vi) Formula of its chloride: With a valency of 2 for Sulphur and 1 for Chlorine, the formula is $SCl_2$.