Minerals Building Blocks of Rocks Minerals Building Blocks of Rocks 1

MineralsBuilding Blocks of Rocks1

Mastering Chapter 2 You should know:

What minerals are and how they are different than rocks.

The basic structure of the atom and how atoms are used to build minerals (bonding).

How common elements in the earths crust make up the various mineral families.

How to use mineral physical properties and identify common rock-forming minerals.

The definition of a mineral resource and understand the characteristics of ore deposits.2

What makes minerals and rocks ?Fe, Mg, Si, O, Kchemical compoundsigneous, sedimentary, metamorphic silicon (Si)oxygen (O)iron (Fe)quartzorthoclasebiotitegranitesandstonegneissElementsMineralsRocks3

The basic atom model (inside the atom)Protons Electrons Neutrons electron shells Atomic number number of protons determines chemical characteristics range from 1 (H) to 92 (Ur)

Atomic mass protons + neutrons neutrons add atomic weight same atom can have varying number of neutrons-- isotopesnucleus4

Germanium atoms (Gr)cobalt (Co) atoms bonding with copper (Cu) atomssilicon + oxygen(silicate tetrahedron)Oxygen (4)Silicon (1)5

Elements and the Periodic Table (PT)ELEMENTS Considered a pure substance each element has its own atomic number About 118 known elements (92 natural, 26 synthetic)

Elements possess distinctive physical properties hardness, boiling points solid, liquid, or gas6

increasing atomic numbersGroups similarpropertiesPeriodsNon-metalsMetalloids7

Interpreting the PT-

79Au197.0GoldAtomic number number of protonsElemental symbolAtomic weight protons + neutronsElement nameSo, observing the PT patterns and the definition of an element, what characteristics distinguish one element from another?Why is an element considered a pure substance????8

I Earth Science better the second week.I will get an A on my exams and quizzes.Discuss with a friend: What are the parts of an atom? be specific (sub-atomic parts).

2. How would you describe a chemical element?

3. What distinguishes one element from another?9

Bonding the atoms (elements)Atoms bond using electrons found at the most outer electron energy shell (valence shell)PeeeeeeeeeeeValence shellElectrons enter higher shell levels afterlower shell levels have been filled.Electrons will either be shared or transferred to other atoms at the valence shell.The atom wants to be satisfied or stableby filling the electron shells to capacity.Electrons are lost OR gained whensatisfying the outer shell (valence shell).Ions the net electric charge of the atom loses an electron (positive charge) gains an electron (negative charge) equal number of electrons/protons (electrically balanced neutral) Cation (+ ions), Anions (-) ions

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Writing a chemical compound(Chemistry nomenclature) Chemical compounds form when combining elementsat a specific ratio (atom to atom) metals (cations) combine with non-metals (anions) Examples:+ Na+ClNaClcationanioncompoundMolecule smallest chemical unit formed by 2 or more atoms held together by electromagnetic forces (bonds) expresses properties of the compoundwatermolecule11

Combining Elements (Atoms) to Make Minerals

Elements are bonded through electrical glue using electronsfrom various element configurations that form chemical compounds. Compounds display completely different physicalproperties.Example:+ NaClNaCl sodium (Na) metallic soft explosive lethal! chlorine (Cl) yellow gas lethal! halite new properties compound can eat it we need it12

Bonding the elements the force that holds the atoms together in a chemical compound

Types of bonding (atomic bonds)

Ionic bonding

Covalent bonding

Metallic bonding

Van der Waals bonding13

The Ionic Bond electrons electrically transferred +Nae=NaClSodium ion wants tolose the electron (+) positive charge ionChlorine ion wants togain the electron(-) charged ioneeeeeeCleeThe Ionic Bond moderate strength and hardness weak bond (salt dissolves in water)1 = valence shell7 = valence shellMineral examples halite (table salt) biotite14

Gain or shareelectrons at the valence shellNaCl = Halite (Salt)Loses electrons at thevalence shell(+) charged ions(-) charged ions15

The Covalent Bond sharing electrons eeeeceeeeceeeeceeeeceeeeceeeecThe Diamondperfect geometryThe Covalent Bondthe strongest bondmost minerals will scratch glassextremely hard to break the bonds16

Metallic bonding tightly packed atoms stickto each other (a form of sharing). Outermost electrons(loosely held) freely move from one atom to the next. good conductors of heat and electricity

heavy dense

malleable (metals bend easily)

polish easilyExamples of metallic minerals: galena (PbS)pyrite (Fe2S)gold (Au)17

Van der Waals bonding weak attraction betweenelectrically neutral molecules; (+) end of the moleculeis attracted to the (-) end of the molecule.Carbon atomsCovalentbondsVan derWaals bonds very weak bonds

easily broken

layers slip past one anotherGraphite exampleSo, why do graphite and diamond displaydifferent physical properties (hardness???)They are both composed of carbon. 18

I Earth Science. I will get an A on my exams and quizzes.Discuss with a friend: What part of the atom bonds together to form compounds?

3. Explain the differences between ionic, covalent, metallic, and Van der Waals bonds. 19

What objects below do you think are minerals??GoldGasolineDiamondWaterWoodWhat are Minerals?20

Why are gold, pyrite, and diamond considered minerals?

The 5-part mineral definition: Naturally occurring Inorganic (non-living) Homogeneous solid Definite chemical composition Definite crystalline internal structure 4,000 different minerals (fits 5-part definition)

25 common minerals combined to form rocks21

I Earth Science. I will get an A on my exams and quizzes.Discuss with a friend:What is the 5-part definition of a mineral?

2. Name 3 substances that are NOT minerals and 3 substances that are minerals.Is ice a mineral? Is water a mineral? why or why not?22

Do all minerals possess a definite or specificchemical composition?Atomic substitution: Two elements can have similar sizes and be substituted within a compound.

Bonding properties are similar.Example: the mineral Olivine series (Fe2+, Mg2+) Both ions are similar in size and charge. Ions exchange (in ratio) with each other within the crystal lattice.Olivine seriesFe2SiO4Mg2SiO4(Fe,Mg)2SiO4fayoliteforsteriteolivine23

Whats inside a mineralA minerals crystalline structure (internal geometric shape) is the result of the atomic arrangement of atoms (how the atoms align).Cl (Chlorine atom)Na (Sodium atom)Dependent on: the size of various combining ions how the ions bond together24

Do ALL minerals grow and show the observer their crystalline shape? (how the atoms combine)Fe2SPyriteQuartzSiO225

Why do some minerals show their internal structure to the observer?26

large gypsum crystalsformed 150 feet below thesurfaceEnough spaceEnough timeEnough solutionChihuahua Desert, Mexico27

The atomic arrangement of atoms in a liquid there is none atoms are randomly arranged an amorphous solid a liquid-type solid possessing no internal structure amorphous material has no melting point Example: glass, plastic, waxamorphousstructurecrystallinestructureWaxesGlassPlastic28

I Earth Science better the second week.Discuss with a friend: What dictates a minerals crystalline structure?

2. What conditions must be met to form perfect crystal faces?

Do all minerals show their crystalline structure to the observer (why/why not)?

4. Describe the differences between amorphous and crystalline structures.29

Mineral Identification Minerals are properly identified using a combination of physical properties that reflect the minerals crystalline structure and chemical composition. Physical Properties Used to Identify Minerals luster how the mineral reflects light hardness the resistance to scratching crystal form angle between crystal faces cleavage breaks along atomic planes of weakness streak color of the powdered residue left on a porcelain plate color most noticeable, least reliable density How heavy is the mineral for its size?30

Luster of the MineralHow the mineral reflects light Is the mineral metallicor non-metallic?Metallic luster shiny, like polished metalNon-metallic (vitreous, resinous, pearly, greasy, earthy) vitreousglassyresinoustree sappearlypearlsgreasyearthychalk31

Hardness of a MineralIs the mineral soft or hard, or how resistant is it to scratching? governed by the minerals crystal structure and chemical bonds the stronger the bond, the harder the mineralRelative hardness,not uniformMohs Hardness Scale32

Crystal faces any solid body that has grown withflat planar surfaces called crystal faces

The same mineral may grow in a large, small, or skinny form, but the ANGLE between crystal faces will always remain the same.

reflects the internal atomic arrangement of atoms

proved by Danish physician- Nicolaus Steno, 1669

Stenos Law states:The angle between any corresponding pairs of crystal faces of a given mineral is constant no matter what the overall shape or size of the crystal might be.33

Examples of atom by atom crystal growthexhibiting various anglesfat, skinny, tall, short