Question

On moving from left to right in a period of the modern periodic table, the atomic number of the elements increases. What happens to the size of elements generally on moving left to right in a period ?

• A. Increases
• B. Decreases
• C. Remains the same
• D. First increases then decreases

Answer 1

The correct option is B Decreases

From moving left to right in a periodic table generally atomic sizes decrease as the atomic number (i.e., the number of protons and electrons) increases but the number of shells remain the same.
Therefore, the force of attraction between the nucleus and the outermost shell of electrons (effective nuclear charge) increases, thus leading to a decrease in size.