Question

if an elemnt has only one electron in its outermost ener6 level then its likely to be metallic or non metallic?

Answer 1

The element is likely to be metallic as since it only has one electron in the outermost shell the effective nuclear charge will be low and it is more likely to donate an electron.

Answer 2

the element is most likely metallic.

metallic character of an element is determined by its tendency to give away electrons to achieve a stable outermost shell.
if there's only 1 valence electron, a stable outermost shell can be obtained by accepting 7 electrons or giving away 1 electron. giving away 1 electron requires a lot less energy than accepting 7. therefore the element is more likely to give away its electron, and is thus mostly metallic in nature.

(unless it's hydrogen which is an exception)