Question

In the third period of the periodic table, sodium is followed by magnesium, aluminum, silicon, and phosphorus. Which of these elements has the smallest atomic size?

a) sodium
b) magnesium
c) aluminum
d) silicon
e) phosphorous

Answer 1

Answer: Option (e) is the correct answer.

Step-by-step explanation:

Elements of third period from left to right are sodium, magnesium, aluminium, silicon and phosphorous. Also it is known that when we go from left to right then there will be decrease in atomic size of atoms or elements.

Therefore, out of the given options phosphorous is at the top right. Hence, we can conclude that phosphorous is the element which has the smallest atomic size.

Answer 2

Answer: The correct answer is Option e.

Step-by-step explanation:

All these elements belong to period 3 in a periodic table.

Atomic size is defined as the distance between the nucleus and the outermost shell of an element.

In a group, electrons get added up in the same shell and the attraction between the nucleus and the outermost electron added increases. This results in the contraction of size of an element.

Period 3 elements are in the order Sodium, Magnesium, Aluminium, Silicon and Phosphorous.

Hence, phosphorous has the smallest atomic size. Therefore, the correct answer is option e.