Question

A part of the periodic table is shown below with one element missing: Based on the above table, answer the following questions:
(i) Name the element that has duplet structure.
(ii) Name the lightest alkali metal.
(iii) Name the halogen of period 2.
(iv) Identify the missing element

Answer 1

Explanation:

1st one helium

3rd one chlorine

Answer 2

Periodic Table

Explanation:

The picture is missing in the question. Please refer to the attached picture for the periodic table.

(i) There are two elements which follow the duplet rule: Hydrogen (H) and Helium (He). Both these elements have 1s orbital. They can accommodate 2 electrons.

(ii) Lithium (Li) is the lightest metallic element with atomic number 3.

(iii) Halogens in the given part of the table are Fluorine (F) and Chlorine (Cl) with atomic number 9 and 17 respectively.

(iv) The missing element is Phosphorus (P), with atomic number 15.