Question

as the atomic number increases within a group of elements atomic radius usually decreases remains the same as the one above increases decreases then increases

Answer 1

As the atomic number increases within a group, the atomic radius increases due to the addition of electron shells and higher principal energy levels. Within a period, the atomic radius decreases as the atomic number rises because an increasing nuclear charge pulls valence electrons closer.

Step-by-step explanation:

The question concerns trends in atomic size or atomic radius on the periodic table with respect to atomic number (Z). When considering elements within a group (a vertical column on the periodic table), the atomic radius tends to increase as the atomic number increases. This pattern occurs because as one moves down a group, additional electron shells are added, and these occupy greater volumes due to their higher principal energy levels, outweighing the effect of the increasing nuclear charge.



Contrarily, within a period (a horizontal row on the periodic table), the atomic radius decreases as the atomic number rises. As we move across a period, the valence electrons are added to the same energy level, while the number of protons (and the resulting nuclear charge) increases, pulling the electrons closer and thus decreasing the atomic radius.