EPS 101 Spring 2003– Adrian Brearley - Lecture 4

Minerals - Building blocks of rocks

Keywords and concepts

Mineralogy – field of geology dedicated to the study of the composition, structure, appearance, stability, occurrence and associations of minerals and what they tell us about processes in the Earth.

Mineral – Naturally occurring, solid crystalline substance, generally inorganic, with a specific chemical composition.

Crystalline substance – solid material in which the constituent atoms are arranged in an orderly, three dimensional array.

Amorphous substance – solid substance in which the atoms have no ordered three dimensional arrangement

Chemical element - the set of atoms having the same number of protons in their nuclei. e.g. all atoms of hydrogen have 1 proton in their nuclei, whereas all atoms of carbon have 6 protons in their nucleus. Chemical elements are indicated in shorthand form - abbreviations - some are obvious, some are not. For example, shorthand for oxygen, the gas that is essential for human life has the abbreviation C, nitrogen - N, carbon, C, hydrogen - H. Less obvious ones are elements like iron - Fe, sodium - Na - many of these abbreviations come from Latin or Greek words for these elements.

Atomic structure of matter

Atom – smallest unit of a chemical element that retains the physical and chemical properties of that element. Consists of a nucleus and surrounded by one or more electron.

Nucleus - dense core of an atom that contains almost all mass of atom – consists of protons and neutrons.

Proton – particle with a mass of 1 atomic mass unit and a positive electrical charge of +1. One or more protons occur in the nucleus of the chemical elements.

Neutron – particle with a mass of 1 atomic mass unit (same as proton) but is electrically neutral (uncharged). One or more protons occur in the nucleus of the chemical elements.

Electron – negatively charged particle (-1) with no mass that occurs in orbitals or shells within an atom, surrounding the nucleus of protons and neutrons.

Atomic number of an element – number of protons in the nucleus of an atom. All atoms of the same element have the same number of protons e.g. carbon (C), atomic number (Z) = 6.

Atomic mass of an element - sum of the masses of the protons and neutrons in the nucleus of an atom.

Isotope – atom or atoms of a given chemical element that has a different number of neutrons and different atomic mass e.g. C –12, C-13, C-14.

Ion – atom that has lost or gained an electron or electrons and has either a positive or negative net charge.