Atoms to Minerals – Key Ideas

Matter I s anything that has mass and volume. Mass is the amount of material in an object. 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 A ll matter is made up of elements. An element is a substance that cannot be broken down into a simpler substance (ex. oxygen, gold).

Atoms An atom is the smallest part of an element that still has the characteristics of that element. protons (+) neutrons (neutral) electrons (-) The protons and neutrons are found in the nucleus of the atom. The electrons move around the nucleus.

Compounds A substance that is made of two or more elements that are chemically combined is called a compound. 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 must occur naturally; must be a solid; must have a definite chemical composition (elements are combined in definite proportions); its atoms are arranged in an orderly pattern, it must be inorganic (not made by any process involving anything living). In order for a substance to be called a mineral, it must meet the following criteria:

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) The two most abundant elements are oxygen and silicon (found in 90% of the minerals).

Silicates These minerals are called silicates. They are made of a basic unit of four oxygen surrounding one silicon – the silica tetrahedron.

Carbonates Made of Oxygen and other metallic elements and the carbonate ion (CO 3 2- ). May contain Calcium, found in the rocks limestone and marble. Can be dissolved by acids, especially important here in NYS because of our acid rain problem.

Oxides Compounds of oxygen and a metal. Because of the metal content, these minerals may rust easily (or have brown discoloration if exposed to the atmosphere). Ex. –Hematite –Magnetite

Mineral Formation Minerals are usually formed in one of the following ways: First way: Solidification of magma (molten rock). Atoms easily move around in the liquid magma and slowly combine together to form mineral compounds.

Mineral Formation Second way: evaporation. 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.