second
The lightest known metal in the world is lithium. It is an alkali metal with a low atomic mass and density, making it extremely light compared to other metals.
Lithium is the lightest element metal with a relative atomic mass of 7 (3 protons, 4 neutrons).
The lightest 'non-metal' could be Hydrogen and Helium! Both are gases, and therefore, not a metal.
The lightest metal is lithium.
Lithium is the lightest transition metal.
Iridium is the most strongest, rarest, densest, expensive, lightest metal ever known
Boron (symbol B) with a relative mas of 10.811.
lithium
The lightest alkaline earth metal is Beryllium(Be) having atomic mass 9.012 dalton. The heaviest element in this family is radium.
Cobalt.
Helium
The lightest metal element is lithium, with an atomic number of 3 and an atomic weight of around 6.94. It is also the lightest metal that is a solid at room temperature and is commonly used in batteries and other electronic devices.