chapter 5: atoms to minerals. chapter 5.1 matter and atoms
TRANSCRIPT
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