Astronomers tallying up all the normal matter—stars, galaxies and gas—in the universe today have come up embarrassingly short ...

Two hydrogen atoms covalently bond to form hydrogen gas. Two oxygen atoms covalently bond to form oxygen gas. There are twice as many hydrogen atoms as oxygen atoms so more hydrogen gas is formed.

Hydrogen is an element; it exists naturally as a molecule. Each hydrogen molecule ... Hydrogen cars help to reduce greenhouse gas emissions. They either burn hydrogen in an engine or they react ...

Click on “Methane” and tell students that methane is a gas that is used in gas stoves and ... Then show students the animated Snap Cube model of a methane molecule. Click on “Hydrogen Peroxide” and ...