Question

How does metallic character change across a period?

Answer 1

To a first approximation, ALL the elements are metallic.........With the exception of hydrogen, non-metals lie on the right hand side of the Periodic Table as we face it.

Explanation:

Look at the Periodic Table. Most of the elements are metals, i.e. most of the elements are NON-MOLECULAR materials in which the valence electrons are delocalized across the entire lattice such that the bulk material is malleable, and ductile, and TEND to form CATIONS - all metallic properties.

Of course, a few of the elements are non-metallic, and (sometimes) molecular materials, whose higher nuclear charge tends to polarize electron density, giving chemically oxidizing species species - certainly this is true of non-metallic oxygen and fluorine.