facts to know

Facts At Your Fingertips: The living world – Amazing science facts MOST COMMON ELEMENTS In the universe: Hydrogen—75% Helium—23% Other elements—2% In the Earth’s crust: Oxygen—47% Silicon—28% Aluminum—8% Iron—5% Calcium—4% Sodium—3% Potassium—3% Magnesium—2% In the human body: Oxygen—61% Carbon—23% Hydrogen—10% Other elements—6% RAREST ELEMENT The rarest element naturally occurring on Earth is francium. Only about … Read more