Explain why atomic radius decreases as you move to the right across a period for main group elements but not for transition elements Match the words in the left column to the appropriate blanks in the sentences on the right. proton
larger
constant
neutron
decreases
smaller
As you move to the right across a row in the periodic table for the main group elements, the effective nuclear charge (Z1) experienced by the electrons in the outermost principal energy level resulting in a stronger attraction between the outermost electrons and the nucleus increases and this results in a atomic radi.
Across the row of transition elements, the number of electrons in the outermost principal energy level (highest n value) is nearly constant. As another is added to the nucleus with each successive element, another electron is added, but that election goes into an Tighet 1 orbital (a core level). The number of outermost electrons stays constant and they experience a roughly constant effective nuclear charge, keeping the radius approximately after the first couple of elements in the series.