What occurs to the covalent radius as you move across a period in the periodic table?

As you move across a period in the periodic table, the covalent radius decreases due to increased nuclear charge. This occurs because, as you progress from left to right, protons are added to the nucleus of the atoms, increasing the nuclear charge. This stronger positive charge of the nucleus attracts the electrons more effectively.

While electrons are also being added to the outer shell, they do not significantly increase the distance from the nucleus due to the increased attraction caused by the additional protons. The overall effect is that the electrons are pulled closer to the nucleus, resulting in a smaller covalent radius.

This trend underscores the importance of the balance between nuclear charge and electron-electron repulsion within an atom, leading to a progressive decrease in atomic size across a period.