Review of Sc.10 and Chapter 5 Earth

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Review (Chapter 3 and Science 8/9/10)Matter is anything that has mass and volume.All matter is composed of elementsAn element is a substance that cannot be broken into

simpler substances by ordinary chemical means. Periodic Table!!!

An atom is the smallest particle of an element that has all the properties of that element. Each atom has a nucleus that contains protons (positively charged), and neutrons (no charge). The moving charged particles are called electrons and they orbit the nucleus.

Isotopes are atoms of the same chemical element with different mass numbers (different numbers of neutrons).

Compounds are substances that contain two or more elements chemically combined.

Compounds are formed when atoms bond

Ionic bond: the bond that forms as a result of the attraction between positively and negatively charged ions; a transfer of electrons, (Metal + Non-Metal)

Covalent bond: The bond formed from the sharing of electrons by atoms, (Non-Metal+ Non-Metal)

Metallic bond: atoms become positively charged ions, sea of electrons

What is a mineral? In order for a material to be called a mineral several

things must be true: Occurs naturally Is a solid Has a definite chemical composition (elements combined

in definite proportions Has its atoms arranged in an orderly pattern Is inorganic (not formed by any process involving plants,

animals, or other organisms.) Water is not a mineral because it is not solid. Window glass is not a mineral because it does not occur

naturally. A pearl is not a mineral because it is formed by an

oyster. Coal is not a mineral because it is made from plant

remains, it lacks a definite composition, and its atoms are not arranged in an orderly way.

Minerals may be elements or compoundsThe two most abundant elements are oxygen and silicon

= These are found in more than 90% of the minerals in the crust.

The eight most common elements in the Earth’s crust are: Oxygen, Silicon, Aluminum, Iron, Calcium, Sodium, Potassium, Magnesium.

Most minerals are compounds. For example Quartz is a compound of silicon and oxygen.

A few minerals are composed of single elements called native minerals, or native elements. = Gold, Silver, Copper, Sulfur, and Diamond.

Minerals can form in several ways:Many form out of molten earth material or magma. Some form when water containing dissolved ions

evaporate. (Halite forms when salt water evaporates.) Minerals can be changed into different minerals by heat,

pressure, or the chemical action of water.

Structure of Minerals: All minerals are crystalline. Their atoms are arranged in a particular

pattern. Minerals are often found as crystals: a regular geometric solid with

smooth surfaces called crystal faces. The angle at which crystal faces meet is always the same for each

kind of mineral and is helpful for identification purposes. Only 6 basic crystal shapes occur: cubic system, orthorhombic

system, tetragonal system, triclinic system, hexagonal system, monoclinic system (pg. 99 of textbook).

Not all crystalline substances have crystal faces. Inadequate space to grow.

More than 90 % of the minerals in Earth’s crust are members of the silicates. (Compounds of the elements silicon and oxygen + one or more metallic elements.)

The basic unit (four oxygen atoms packed around a silicon atom) is held together by covalent bonds between the silicon atom and oxygen atoms. This makes a geometric figure called a tetrahedron.

Silicate minerals are built around the silica tetrahedron. The crystal shape, hardness, cleavage, and density of a mineral are

determined by the internal arrangement of its atoms or ions.

Chapter Five.2Please take notes on the following information…

Identifying Minerals: Over 2000 minerals are known. There are common

minerals (quartz, feldspar, mica, calcite…) and rare (gold, diamond) minerals

Common minerals that make up the majority of the Earth’s crust are called rock-forming minerals.

Most rock forming minerals are silicate minerals.

Minerals are identified by their physical properties.

The study of minerals and their properties is called mineralogy

Identification by Inspection and Tests:Colour: Obvious but not very usefulLuster: The way it shines in reflected light. Metallic or

Nonmetallic, pearly, earthy, vitreous (like glass) Crystal Shape: Only helpful if they have had time and room

to form giving their atoms or ions (an atom or group of atoms in a negative or positive charged condition) time to arrange themselves in patterns.

Streak: colour of the mineral when it is finely powderedCleavage: breakage along smooth planes. This depends

upon zones of weakness in the crystal structure.Hardness: Mohls’ scale. Resistance to being scratched.Fracture: the broken surface is irregular and not in a flat

plane.Specific gravity: the ratio of the weight of a mineral to the

weight of an equal volume of water.The acid test: Hydrochloric acid

Special Properties of Minerals:Magnetic: Magnetite-an iron ore, LodestoneTaste: Halite=Rock SaltFluorescence: fluorite, calcite (glow under UV)

Phosphorescent: (glows after UV exposure) willemite and sphalerite

Radioactive: uranium (harmful)Double refraction: (splitting the light ray into two parts.) Iceland Spar – a type of Calcite

Silicates: From Silica Tetrahedrons Silica tetrahedron = nature’s most important building

block for minerals. Quartz: hardest (7) of the common minerals, glassy or

greasy luster, fracture is shell-like or irregular, colour varies. It is the second most abundant mineral in Earth’s crust. (Important part of granite)

Feldspar: the most abundant family of minerals in Earth’s crust. (60%)

Feldspar’s have three major properties: two directions of cleavage, a hardness of 6, and a pearly luster.

Two major groups of Feldspars: potassium feldspars and sodium calcite feldspars. (based upon the ionic structure)

Potassium Feldspar: Orthoclase Sodium-calcite feldspars are called plagioclase feldspars:

Albite and oligoclase.

Silica Tetrahedrons continued….Mica: soft silicatesTalc: softest mineral #1 on Mohls’ scaleAmphiboles are a family of complex silicate

minerals = Hornblende long needle-like crystalsHornblende is also a Ferromagnesian silicateFerromagnesian silicates all contain atoms of iron

and magnesium AND they are always dark in colour.

Pyroxenes: Augite (Awjyte) is the most common member of this family. (Cleavage surfaces meet nearly at right angles.) (shorter, stouter crystals)

Olivine, Garnets, and Kaolinite “oh my”…page 55

Non-Silicates: Carbonate group: made of one carbon atom

combined with three oxygen atoms and has a negative charge of two.

A carbonate mineral = carbonate groups joined with various metal ions. (limestone and marble)

Most common = Calcite (ACID TEST) Colourless transparent calcite is called Iceland spar =

properties of double refraction Dolomite is calcium magnesium carbonate Copper carbonates = malachite (green) and azurite

(blue) Iron carbonate = siderite (brown or yellow-brown)

Iron Oxides and Sulfides:Minerals that contain large amounts of the metal

element iron.ECONOMICALLY IMPORTANT…(will be discussed later) Iron tends to be combined with either oxygen or

sulfur to form an oxide or sulfide.Oxide: a mineral consisting of a metal element

combined with oxygen.Sulfide: a metal element combined with sulfur.Each iron-bearing mineral has its own identifying

properties.Hematite: most common. ALL leave a red-brown

streak on the streak plate.Magnetite: attracted to a magnet. Lodestone is a

highly magnetic variety of magnetite…natural magnet.

Pyrite: iron sulfide…fool’s gold

Now for some Visuals

http://en.wikipedia.org/wiki/List_of_minerals_D_(complete)#mediaviewer/File:Dioptase-36918.jpg

Dioptase: Image by Rob Lavinsky

Hornblende: this is a sample from the Smithsonian Museum of Natural History.http://hyperphysics.phy-astr.gsu.edu/hbase/minerals/hornblende.html

Feldspar: The most abundant family of minerals in the Earth’s crusthttp://www.beg.utexas.edu/mainweb/publications/graphics/feldspar.htm

Pure Quartzhttp://commons.wikimedia.org/wiki/File:Pure_Quartz_at_Senckenberg_Natural_History_Museum.jpg

Muscovite from Mitchell County North Carolina http://geology.com/minerals/muscovite.shtml

Garnet: These share a common crystal structure. http://geology.com/minerals/garnet.shtml

Calcite: Carbonate

Azurite and malachite from Morenci, Arizona: a deep blue copper carbonate.

Pyrite with hematite from Rio Marina, Isle of Elba, Italy Fool’s Gold

Fluorite in normal light and under short wave ultraviolet lighthttp://geology.com/articles/fluorescent-minerals/\

Fluorescent rocks and minerals

Dolomite crystals from Penfeld, New York

Cinnabar: a toxic mercury sulfide mineralhttp://geology.com/minerals/cinnabar.shtml

The End…HomeworkComplete “5.2 Section Review” on page 102 of your textbook

Coming up…Section 5.3 Identifying Minerals & Lab