Chemistry 2006 JAMB Past Questions - Question 36: A decrease in atomic size and an increase in nuclear charge .cross a period lead to

Correct Answer

C

Explanation

As you move across a period (horizontal row) in the periodic table from left to right, there is a decrease in atomic size and an increase in nuclear charge. This is due to the fact that each successive element in a period has one more proton in its nucleus compared to the previous element.

The decrease in atomic size can be attributed to the increasing nuclear charge pulling the electrons closer to the nucleus. As the number of protons in the nucleus increases, the positive charge of the nucleus exerts a stronger attractive force on the negatively charged electrons in the outer energy level.

The increase in nuclear charge also affects the electron configuration. Electrons are added to the same energy level, but because of the increased nuclear charge, they experience a greater force of attraction. This leads to a tighter hold on the electrons and a reduction in the overall size of the atom.

In summary, across a period, the increase in nuclear charge results in a stronger attraction to the electrons, causing the atomic size to decrease.