Question

Density of elements across a period increases
gradually to maximum and then slight decrease may
be noticed .why?
​

Answer 1

Explanation:

Generally, the atomic radius decreases across a period from left to right and increases down a given group.

Moving from left to right across a period, electrons are added one at a time to the outer energy shell. Since the number of protons is also increasing, the effective nuclear charge increases across a period. This causes the atomic radius to decrease.

As radius decreases across a period and the atomic number increases so density increases across a period.

Answer 2

Explanation:

Generally, the atomic radius decreases across a period from left to right and increases down a given group.

Moving from left to right across a period, electrons are added one at a time to the outer energy shell. Since the number of protons is also increasing, the effective nuclear charge increases across a period. This causes the atomic radius to decrease.

As radius decreases across a period and the atomic number increases so density increases across a period.