Atoms+to+Minerals

=**Atoms to Minerals – Key Ideas**=
 * __Matter__** is anything that has //mass// and //volume//. **Mass** is the amount of material in an object. It is often discussed as weight, but this is not correct. In order to have weight you must have gravity, but you do not need gravity to have mass ([|an astronaut in space] does not have weight, but they have mass!).

=Elements and Atoms=

All matter is made up of __[|elements]__. An element is a substance that cannot be broken down into a simpler substance (ex. oxygen, gold). An [|atom] is the smallest part of an element that still has the characteristics of that element. An atom is made of particles called protons (+), neutrons (neutral), and electrons (-). The protons and neutrons are found in the nucleus of the atom. The electrons move around the nucleus.
 * The Periodic Table lists all the known elements with the //atomic number// (number of protons) and the //mass number// (number of protons and neutrons)
 * All elements that are the same have the same atomic number (ex. all carbonatoms have 6 protons – atomic number of 6). This is not true of the neutrons. Atoms of the same element that have a different number of neutrons (mass number) are called __isotopes__. For example Carbon-12 has 6 protons and 6 neutons, while Carbon-14 has 6 protons and 8 neutrons.

=**Compounds**=

A substance that is made of two or more elements that are chemically combined is called a __compound__. For example, water is a compound made up of two hydrogen atoms and one oxygen atom. The smallest part of a compound that still has the characteristics of the compound is called a __molecule__.

=Minerals and Mineral Structure= In order for a substance to be called a mineral, it must meet the following criteria: 1. must occur naturally; 2. must be a solid; 3. must have a definite chemical composition (elements are combined in definite proportions); 4. its atoms are arranged in an orderly pattern, 5. it must be inorganic (not made by any process involving anything living);


 * Most of the minerals in the Earth’s crust are composed of only eight elements (some of these elements may be joined together as compounds) – [|in reference table page 11]. The two most abundant elements are oxygen and silicon (found in 90% of the minerals). These minerals are called silicates. They are made of a basic unit of four oxygen surrounding one silicon – the //silica tetrahedron//.


 * All minerals are crystalline, meaning they are made of atoms arranged in a regular pattern. Some minerals are found as //crystals//. Crystals are regular geometric solids with smooth surfaces called faces. The shape of the crystal, as well as the hardness of the crystal (Ch. 4) is determined by how the atoms are arranged.

=Mineral Formation= Minerals are usually formed in one of the following ways: 1. Solidification of magma (molten rock). Atoms easily move around in the liquid magma and slowly combine together to form mineral compounds. The faster the magma cools, the less time the mineral grains have to form. This will make the mineral grains smaller. 2. Evaporation of water containing dissolved atoms. When the water begins to evaporate, the dissolved atoms are left behind and arrange themselves into certain minerals. For example, sodium and chlorine form salt (halite) when seawater evaporates.