chapter 5. matter & atoms: matter what is matter? anything with mass & volume are minerals...
TRANSCRIPT
Chapter 5
Matter & Atoms: Matter
What is matter?anything with mass & volume
Are minerals made of matter?yes
Why/why not?b/c have mass & volume
Matter & Atoms Ch. 5 Sec. 1
What makes up matter?elements
What is an element?a substance made of only one type of atom
What are atoms?
~the smallest part of an element
Matter
Structure of an AtomSubatomic
particleLocation charge symbol
proton nucleus (center of atom) positive p+
neutron nucleus (center of atom) neutral (no charge)
n0
electron orbit around nucleus (located in energy levels)
negative e-
17 p+
18 n0
# protons (+) equals # electrons (-) Electrons in shells Number of outermost electrons determine types of bonding
Argon
Outermost (Valence) shell
Structure of an Atom
Electrons & Energy LevelsWhere are
electrons found in an atom?around nucleus
in energy levels1st shell up to 2
electrons2nd + shells up to
8 electronsFill a shell before
move to next
How many more electrons can the 3rd shell hold?
Classifying Atomsperiodic table
rows (periods)L R
increase protons
columns (groups/ families)similar
chemical properties
16
Classifying Atoms: The Periodic Table# of protons
protons +
neutrons
also # of electrons
bigger of the 2 #s
to figure out # of neutrons…atomic mass – atomic number = neutrons
The # of p+ determines element’s properties
Isotopes
What is an isotope?elements w/ same #
of protons, but different # of neutrons& therefore… different
masses
How are isotopes used in geology?geologic dating
Bonding of AtomsWhat affects the
bonding of atoms?the # of outer
(valence) level electronsIf valence shell is
full, what happens?stable, won’t bond
If not full, what happens?
unstable, will bond
What causes a Covalent Bond?shared electrons
Bonding of Atoms
What causes an ionic bond?electrons are lost or gained
opposite charged ions attract
common in minerals
Atoms & Bonding InteractiveBonding of Atoms
What is a metallic bond?bond formed between metal atoms
e- move freely around metal ions
Bonding of Atoms
Compounds & MixturesWhat is a
compound?elements combine in
a fixed proportionnew properties resultcan only be separated
by chemical means (ex. electricity)
Ex. water 2 hydrogen : 1 oxygen
Ex. salt 1 sodium : 1 chlorine
Compounds & MixturesWhat is a mixture?
elements/compounds can be in any proportionkeep original propertiesmost can be separated by physical means
(ex. evaporation, filtering, magnet, etc.)Ex. salt water, sand & water, iron & salt
What is a mineral?To be
classified as a mineral a substance must meet 5 criteria…
Composition & Structure of MineralsCh. 5 Sec. 2
1. must be naturally occurringcannot be
man-made!!!
What is a Mineral?The 5 Criteria
2. must be solidCan NOT be a liquid or
gas!!!
Minerals can be crushed into powder…and still be considered
a mineralWhy?
b/c still a solid
What is a Mineral?The 5 Criteria
3. must have a definite chemical compositiona chemical
“recipe” for making that mineralchange the
“recipe”… change the mineral!!!
What is a Mineral?The 5 Criteria
4. atoms must be arranged in an orderly pattern (“internal arrangement of atoms)crystalline
structure
What is a Mineral?The 5 Criteria
must be inorganicCANNOT be made from
anything that is or was living!What is the exception?
shells that contribute material to minerals are PRODUCED by living things
BUT the shells themselves are not alive
What is a Mineral?The 5 Criteria
What are the Most Common Rock-forming Minerals in Earth’s Crust?
(by mass)
SilicatesSilicon Oxygen Tetrahedron Animation
O2 -
O2 -
O2 -
O2 -
Si4+
The Silicon-OxygenTetrahedron—anexample of ionic bonding.
Most minerals are composed of only 8 elements!What are the
2 most abundant elements in Earth’s crust?silicon &
oxygen
How do minerals form?1. solidification of
molten materials2. evaporation of
seawater3. transformation
by heat, pressure, or chemical action
Crystal Structure of MineralsWhat is meant by crystalline structure?
orderly internal arrangement of atomsWhich physical properties are affected by
crystalline structure (internal arrangement of atoms?
shapehardnesscleavage/fracture
halite
What are “crystals”?regular geometric
solid with smooth surfaces called crystal faces
Crystal Structure of Minerals
Systems
Examples
Crystal Structure: 6 Basic Shapes• What is crystal shape?
• angle between crystal faces• characteristic for each type of mineral
• How is this helpful?• can be used to aid in identification
Crystal Structure &Physical Properties
What physical properties are affected by crystal structure?state of matter
solidcleavage
tendency to split along definite planes
hardnessdifferent arrangement =
different hardness Ex. graphite & diamond
Identifying Minerals Ch. 5 Sec. 3
How can we identify minerals?inspecting
them visually
ANDperforming
simple tests
Which properties can be determined visually?color, luster, & crystal shape
should be considered togetherA mineral is rarely identified by a
single property!
Identifying Minerals by Inspection
Why is color important?easily observed
some minerals have distinctive colors
HOWEVER, color is generally unreliable for a positive ID.
Why? impurities or exposure
to air/water can change a mineral’s color
many minerals can be the same color
Identifying Minerals by Inspection
Ex. Quartz (below) & Fluorite (right) Exhibit
a Variety of Colors.
milky quartz
citrine
smokyquartz
amethyst
What is luster?the way a
mineral’s surface reflects light How can we
describe a minerals luster? metallic non-metallic
Identifying Minerals by Inspection
earthy
dull
Galena & Pyrite Display Metallic Luster
waxy
earthy
pearly
vitreous/glassy
resinousadamantine
dull
fibrous
greasy/oily
silky
Examples of Nonmetallic Luster
What is streak?color of a
mineral in its powdered formFor any mineral
the streak color is always the same! even though
specimens can vary in color
ALWAYS place streak plate on a flat surface!Never hold it in your hand.It can break and cut you.
Identifying Mineral Samples by Testing
Examples of Streak
What is cleavage?tendency of a mineral to break along
planes of weak bonding What type of surfaces are normally seen?
flat, shiny surfaces (1, 2, 3, 4, 6 common)
Cleavage Plane Animation
Identifying Mineral Samples by Testing
Examples of cleavage – mica, fluorite, halite, and calciteMuscovite mica
What is fracture?tendency
of a mineral to break unevenly along rough or curved surfaces
conchoidalfracture
Identifying Mineral Samples by Testing
What is a mineral’s hardness?the ease or difficulty
with which the mineral can be scratched What determines
(affects) a mineral’s hardness? internal arrangement
of atoms & bond strength
Identifying Mineral Samples by Testing
softest
hardest
Steel nail
How is the hardness of a mineral measured?compare to a
standard scale Mohs scale of
hardness 1—talc
(softest) 10—diamond
(hardest)
Identifying Mineral Samples by Testing
“Measuring” Mineral Hardnessuse fingernail, copper
penny, glass “scratch” plate, & steel file/plateIf the mineral:
scratches the itemit is harder than that item
is scratched by the itemit is softer than the item
“measures” the mineral’s approximate hardness ~Ex. If the mineral scratches glass, but does not scratch steel (or is scratched BY steel), its hardness is between 5.5 & 6.5 on Mohs Scale
What is specific gravity/density?specific gravity
is the density (mass/volume) of the mineral compared with the density of water (= 1)
Identifying Mineral Samples by Testing
What is double refraction?“seeing double”
Special Properties Used for Mineral ID
What is fluorescence?tendency to glow when
placed under UV light (“black-light”)
http://www.sterlinghill.org/Tour%20information.htm
en.wikipedia.org www.hometrainingtools.com
Special Properties Used for Mineral ID
tastehalite salty
Remember… do not taste anything in the laboratory!
http://mineral.galleries.com/scripts/item.exe?LIST+Minerals+Halides+Halite
Special Properties Used for Mineral ID
magnetismWhat element
would these minerals contain? iron
“lodestone” acts like magnet
magnetite attracted to magnet http://www.minerals.net/mineral/
oxides/magnetit/magneti4.htm
Special Properties Used for Mineral ID
radioactivitygive off subatomic particles
Special Properties Used for Mineral ID
“acid test/ reaction with HCl” carbonates react with HCl & other acids
see fizzing/ bubblingWhy?
releasing CO2 gas
Special Properties Used for Mineral ID
•Is this sample calcite or dolomite?
•calcite•How can you tell?
•Bubbles w/ acid but does NOT need to be powdered first.
•Where could you look if you’re not sure?
•reference tables
Special Properties Used for Mineral ID
odor (smell)sulfur
What does it smell like?
rotten eggs
Special Properties Used for Mineral ID
Minerals Groups Ch. 5 Sec. 4Major silicates
Make up 90+% of mineral in Earth’s crust
Which 2 elements are always in silicate minerals?
Silicon & oxygenWhat does a
silicate molecule look like?
4 oxygen ions surrounding silicon ion
O2 -
O2 -
O2 -
O2 -
Si4+
Feldspar
Mica
Quartz
Olivine
Silicate Mineral Examples
Pyroxene
other silicatespyroxene
family
mica family
amphibole minerals
olivine group
kaolinite
Major SilicatesMuscovite
carbonatescontain CO3 (carbonate)
& metal ions2 most important
calcitedolomite
Common Non-silicate Minerals
oxides & sulfidescontain significant amounts
of ironusually combined with oxygen
(oxide) or sulfur (sulfide)economically important
Why?Used to make steel, magnets,
car parts, medicines, cosmetics, plastics, paints.
Common Non-silicate Minerals
Examples of oxideshematitemagnetite
Example of sulfidespyrite (“fool’s gold”)
Common Non-silicate Minerals
Non-silicate Mineral Examples
halite(halide)
spinel(oxide)
gypsum(Sulfate)
hematite(oxide)
calcite(carbonate)
pyrite(sulfide)
galena(sulfide)