I need help with billing... 1  Payment - get help with making payments online. 2  Billing - get help with billing questions. 3  Usage - learn how to view usage and unbilled usage.  Plan - get help with price plan.
A molecule is the smallest particle of a substance that exists independently. Molecules of most elements are made up of only one of atom of that element. Oxygen, along with nitrogen, hydrogen, and chlorine are made up of two atoms. Look at the model of oxygen above.The two balls represents the two oxygen molecules. molecule is the smallest particle of a substance that exists independently. Molecules of most elements are made up of only one of atom of that element. Oxygen, along with nitrogen, hydrogen, and chlorine are made up of two atoms. Look at the model of oxygen above.
A compound is a molecule that contains at least two different elements. All compounds are molecules but not all molecules are compounds. Molecular hydrogen (H2), molecular oxygen (O2) and molecular nitrogen (N2) are not compounds because each is composed of a single element. single molecule of water is made from two atoms of hydrogen and one atom of oxygen. Mixtures Most matter in the universe is found in mixtures. A mixture is made from two or more substances either elements, compounds or both-that are not chemically combined.