Chapter 5: Atoms to Chapter 5: Atoms to MineralsMinerals

Chapter 5.1Chapter 5.1

Matter and AtomsMatter and Atoms

MatterMatter Anything that has mass (amount of material) and Anything that has mass (amount of material) and

volume (amount of space an object takes up)volume (amount of space an object takes up) Ordinary matter is composed of elements (a Ordinary matter is composed of elements (a

substance that cannot be broken into a simpler substance that cannot be broken into a simpler substance by ordinary chemical means)substance by ordinary chemical means)

200 years ago, John Dalton stated that “each 200 years ago, John Dalton stated that “each element is made up of tiny particles, all alike, element is made up of tiny particles, all alike, called atoms”called atoms”

Dalton describes an atom as the smallest part of Dalton describes an atom as the smallest part of an element that has all the elements properties.an element that has all the elements properties.

Structure of an atomStructure of an atom

In its normal state, a neutral atom as an In its normal state, a neutral atom as an equal number of electrons and protonsequal number of electrons and protons

Atomic # tells how many protons are in the Atomic # tells how many protons are in the nucleus and is equal to the # of electrons in nucleus and is equal to the # of electrons in the electron cloudthe electron cloud

The nucleus has 99.9% of the atoms massThe nucleus has 99.9% of the atoms mass Energy levels of electrons represents how Energy levels of electrons represents how

many electrons each level can hold 2, 8, 18, many electrons each level can hold 2, 8, 18, 32, 21, 9, and 232, 21, 9, and 2

Classifying AtomsClassifying Atoms

Periodic table of elements p. 698Periodic table of elements p. 698 Rows represent the increasing number Rows represent the increasing number

of protonsof protons Vertical columns group these elements Vertical columns group these elements

that have similar chemical propertiesthat have similar chemical properties Mass #; sum of protons and neutronsMass #; sum of protons and neutrons

Isotope – an atom with a different # of neutronsIsotope – an atom with a different # of neutrons PotassiumPotassium

Atomic NumberAtomic Number 1919

SymbolSymbol KK

Atomic MassAtomic Mass 39.10 amu39.10 amu

K has 19 protons (atomic number)K has 19 protons (atomic number) 20 neutrons (atomic mass – atomic # [39 – 19])20 neutrons (atomic mass – atomic # [39 – 19]) 19 electrons; always equals the of protons19 electrons; always equals the of protons

Bonding of AtomsBonding of Atoms

Most substances on earth are not Most substances on earth are not pure they are compounds – contains pure they are compounds – contains atoms of 2 or more elements.atoms of 2 or more elements.

For a substance to be stable it likes For a substance to be stable it likes its last electron level to be filled so its last electron level to be filled so they fill it by losing or gaining they fill it by losing or gaining electronselectrons

Covalent Bonds – share electronsCovalent Bonds – share electrons

Ionic Bonds – when atoms loose or gain an Ionic Bonds – when atoms loose or gain an electron they became charged.electron they became charged.

Gained; [-] ChargeGained; [-] Charge Lost; [+] ChargeLost; [+] Charge The opposite charge will then attractThe opposite charge will then attract

Ion – a charged atomIon – a charged atom A metal looses electrons easily to form positive ions. A metal looses electrons easily to form positive ions.

Therefore they can not join with other metals. Therefore they can not join with other metals. Nonmetals gain electrons easily to form negative Nonmetals gain electrons easily to form negative

ions. This makes them want to bond to the positive ions. This makes them want to bond to the positive metals.metals.

Metallic Bonds – The bonds that Metallic Bonds – The bonds that form between metals cause the form between metals cause the electrons to move around all the electrons to move around all the positive ions.positive ions.

Compounds and MixturesCompounds and Mixtures

Compounds can have properties entirely Compounds can have properties entirely unlike those of the elements of which it is unlike those of the elements of which it is made.made. Salt NaCl Sodium and Chlorine are both Salt NaCl Sodium and Chlorine are both

poisonous to humans when separatedpoisonous to humans when separated Compounds can only be separated by chemical Compounds can only be separated by chemical

means.means. Mixtures – elements keep their own propertiesMixtures – elements keep their own properties

Salt water – water can be separated by Salt water – water can be separated by boilingboiling

Chapter 5.2Chapter 5.2

Composition and Composition and Structure of MineralsStructure of Minerals

What is a mineral?What is a mineral?

A mineral must beA mineral must be Naturally occurringNaturally occurring SolidSolid Definite chemical compositionDefinite chemical composition Orderly arrangement of atomsOrderly arrangement of atoms Inorganic (never alive)Inorganic (never alive)

Most minerals are compoundsMost minerals are compounds Quartz SiOQuartz SiO22; Silicon and Oxygen; Silicon and Oxygen

Native elements – minerals with a single elementNative elements – minerals with a single element Gold (Au), silver (Ag), copper (Cu), Sulfur (S), diamond (C)Gold (Au), silver (Ag), copper (Cu), Sulfur (S), diamond (C)

Rock – different types of minerals and native elements mixed Rock – different types of minerals and native elements mixed togethertogether

How minerals formHow minerals form

Many minerals form from molten rock in which Many minerals form from molten rock in which the atoms can move freely. Once it begins to cool the atoms can move freely. Once it begins to cool the ions move closer together to form chemical the ions move closer together to form chemical bondsbonds

Many different minerals will form. The Many different minerals will form. The composition of the magma will control what type composition of the magma will control what type form.form.

The slower the magma cools the larger the The slower the magma cools the larger the grains.grains.

Can also form from evaporating water – saltCan also form from evaporating water – salt New minerals will form when existing minerals New minerals will form when existing minerals

are exposed to more heat and pressure.are exposed to more heat and pressure.

Structure of MineralsStructure of Minerals

Crystal StructuresCrystal Structures The orderly arrangement of atoms in a The orderly arrangement of atoms in a

mineral often seen as the minerals shapemineral often seen as the minerals shape Salt p. 98Salt p. 98

Crystal is a regular geometrical solid with Crystal is a regular geometrical solid with smooth surfaces called crystal faces.smooth surfaces called crystal faces.

Each mineral has its own crystal formEach mineral has its own crystal form There are six basic shapes p. 99There are six basic shapes p. 99

Silicates – minerals that are Silicates – minerals that are compounds including silicon and compounds including silicon and oxygenoxygen They also may contain a metal atomThey also may contain a metal atom Silica tetrahedron – 4 oxygen Silica tetrahedron – 4 oxygen

surrounding 1 siliconsurrounding 1 silicon

Crystal Structures and Physical Crystal Structures and Physical PropertiesProperties Cleavage – tendency to split along definite Cleavage – tendency to split along definite

planesplanes Hardness – resistance to scratch. Sometimes Hardness – resistance to scratch. Sometimes

the same element can have different the same element can have different hardness based on its internal structurehardness based on its internal structure

Diamond – pure carbon very hardDiamond – pure carbon very hard Graphite – pure carbon very softGraphite – pure carbon very soft

Chapter 5.3Chapter 5.3

Identifying MineralsIdentifying Minerals

Mineralogy – study of minerals and Mineralogy – study of minerals and their propertiestheir properties

Rock Forming MineralsRock Forming Minerals

Identifying Minerals by Identifying Minerals by InspectionInspection

Very rarely are minerals Id. by Very rarely are minerals Id. by one propertyone property

Types of PropertiesTypes of Properties Color – easily observed but, least usefulColor – easily observed but, least useful Luster – how a mineral reflects lightLuster – how a mineral reflects light

2 basic types2 basic types MetallicMetallic NonmetallicNonmetallic

Crystal shapeCrystal shape

Streak – color of a powdered Streak – color of a powdered mineralmineral Metallic minerals streak is at least as Metallic minerals streak is at least as

dark as a specimendark as a specimen Nonmetallic – colorless or whiteNonmetallic – colorless or white

Cleavage – minerals splits along flat Cleavage – minerals splits along flat surfacessurfaces

Fracture – breaks in directions Fracture – breaks in directions other than cleavage planesother than cleavage planes Conchoidial - shell like fractureConchoidial - shell like fracture Splintery – jagged surfaceSplintery – jagged surface Uneven – rough surfaceUneven – rough surface

Hardness – resistance to scratchHardness – resistance to scratch Mesh’s hardness scale 1- 10Mesh’s hardness scale 1- 10

Chapter 5.4Chapter 5.4

Mineral GroupsMineral Groups

Major SilicatesMajor Silicates

90% of the minerals in earth’s crust are 90% of the minerals in earth’s crust are silicatessilicates

Quartz – used in watch movements, prisms, heart Quartz – used in watch movements, prisms, heart lamps, lenses, glass and paints. Crystals are lamps, lenses, glass and paints. Crystals are considered semipreciousconsidered semiprecious

Feldspars – used aluminum atoms in place of Feldspars – used aluminum atoms in place of some of the silicon which become balanced by some of the silicon which become balanced by other metals. It is used in glass and ceramicsother metals. It is used in glass and ceramics

Micas (biotite and muscovite) used as electronic Micas (biotite and muscovite) used as electronic insulators, paints, plastics, rubber and roofing.insulators, paints, plastics, rubber and roofing.

Ferromagnesium SilicatesFerromagnesium Silicates Olivine – gem quality is known as Olivine – gem quality is known as

peridoteperidote Kaolinite – is pure white, a clay Kaolinite – is pure white, a clay

compound used in ceramics, paint and compound used in ceramics, paint and fiberglass also known as china clayfiberglass also known as china clay

Carbonates – negative Carbonates – negative carbonate ions bonded carbonate ions bonded to positive metal ions to positive metal ions

which are used which are used construction. Calcite construction. Calcite and Dolomite give us and Dolomite give us

rock like limestone and rock like limestone and marble.marble.

Oxides – Iron bonded Oxides – Iron bonded with oxygen of sulfur with oxygen of sulfur

(sulfide)(sulfide) Hematite – iron oxide used to Hematite – iron oxide used to

make steel medicine, cosmetics, make steel medicine, cosmetics, plastics and paintsplastics and paints