Atomic number 25, atomic weight 54.9380. Phosphorus (P): Phosphorus is a poisonous, nonmetallic element that helps protect metal surfaces from corrosion. Atomic number 15, atomic weight 30.9738.

arranged by their atomic number. One never knows when one will need the properties of Rutherfordium in a hurry. See if you can organize the first 25 elements of the periodic table in order in the ...