Trends Left to Right

There are two trends that we are focussing on for periodic trends moving left to right on the periodic table in the same period.  They are both related to the fact that as you move from left to right the effective nuclear charge, Z_eff, is increasing.  This means the valence electrons feel a stronger attraction to the nucleus.  This leads to a smaller radius and a higher ionization energy.  Note: this is a general trend and there are some small exceptions.  These typically arise for elements with either full sub-shells or half-filled sub-shells.