The atomic radius decreases from left to right across a period on the periodic table due to increased nuclear charge, which attracts electrons closer, reducing the size of the atom.
The atomic radius represents the size of an atom and tends to change predictably as you move across the periodic table. Across a period, the atomic radius generally decreases from left to right. This decrease is due to the increase in the number of protons in the nucleus, leading to a stronger attraction between the nucleus and electron clouds, pulling the clouds closer and thus decreasing the radius.
When looking at the elements Be, B, C, N, O, and F, you will observe this trend as their atomic numbers increase. However, there are occasional deviations from this trend, such as the atomic radius of oxygen being slightly larger than that of nitrogen, which can be attributed to electron-electron repulsions.
Several factors influence atomic radius, including the number of electron shells, the number of protons in the nucleus, and the shielding effect. As protons are added to the nucleus and electrons to the same energy level, the electrons are pulled closer due to the increased positive charge.