atomic number 5

Definitions of atomic number 5

1. noun

   a trivalent metalloid element; occurs both in a hard black crystal and in the form of a yellow or brown powder
   synonyms: B, boron

   type of:

   chemical element, element

   any of the more than 100 known substances (of which 92 occur naturally) that cannot be separated into simpler substances and that singly or in combination constitute all matter