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Matter and atoms
- Matter is any substance that has weight. It can take the form of a liquid, a solid, or a gas.
- Matter comprises elements and compounds
Atoms and molecules
An element is any matter that cannot be divided further by chemical means. Elements are made up of atoms. Elements can join together to form compounds. A molecule is a type of compound where the atoms of two types of elements have joined together to form a more complex type of matter. The parts of a molecule, in contrast to elements, can be separated by chemical means. For example Sodium and Chlorine are two elements that can join to form Sodium Chloride. We call this chemical bonding. We can use chemistry to separate the Sodium and Chlorine atoms in the molecule to return to two separate elements.
Compounds can be confusing. In general a compound is any matter that contains more than one kind of element. By this definition a molecule is always a compound. However not every compound is a molecule as we can have complex compounds that contain more than one type of molecule. For example water is hydrogen and oxygen forming a molecule. It contains more than one element therefore it is a compound. But imagine if we had water and carbon combined. This would still be a compound but not a molecule since it would contain a molecule and a carbon element.
Atomic particles
There are three particles comprising atoms: protons, neutrons and electrons.
Protons and neutrons comprise the nucleous of the atom. A proton is positively charged. A neutron has no charge.
Electrons orbit around the nucleous in concentric rings. Electrons are negatively. Because of this protons and electrons attract each other.