Question

How does the metallic and non- metallic character vary on moving from left to right in a period?

Answer 1

As we move from left to right in a period the number of valence electrons increases by one at each succeeding element but the number of shell remains same. Due to this effective nuclear charge increases. More is the effective nuclear charge, more is the attraction between nuclei and electron.
Hence, the tendency of the element to lose electrons decreases, this results in a decrease in metallic character. Furthermore, the tendency of an element to gain electrons increases with an increase in effective nuclear charge, so non-metallic character increases on moving from left to right in the period.