STRUCTURE OF ATOMS

1
STRUCTURE OF ATOMS
DIAMETER 10-8 CM (0.00000001CM) ATOMS CONSISTS
OF OUTER ELECTRONS
NUCLEUS COMPOSED OF PROTONS AND
NEUTRONS CHARGE OF A PROTON
1---------1.6010-19 C MASS OF A PROTON
1.6710-24 G 1 ATOMIC MASS UNIT (AMU) NEUTRONS
--------- NEUTRAL   238 92 U MASS ------- AMU
238 AMU    
2
STRUCTURE-CONTD
ELECTRONS TRAVEL AROUND THE NUCLEUS   ME
MP/1836 ------- MP ME 1836   NUMBER OF
PROTONS (Z) ATOMIC NUMBER   NUMBER OF ELECTRONS
NUMBER OF PROTONS   ISOTOPES ATOMS OF SAME
ELEMENT WITH DIFFERENT NEUTRON NUMBER ( SAME Z
BUT DIFFERENT ATOMIC WEIGHT)  
3
MODEL OF AN ATOM-Fig
Figure 2.5 Model of an atom.
4
MINERALS
MINERALS NATURALLY OCCURRING SOLIDS WITH
SPECIFIC CHEMICAL COMPOSITIONS AND DEFINITE
INTERNAL STRUCTURES e.g., QUARTZ, EMRALDS,
ETC   ROCKS NATURALLY OCCURRING AGGREGATES OF
ONE OR MORE ELEMENTS   ELEMENTS FORM OF MATTER
THAT CANMNOT BE BROKEN DOWN INTO SIMPLER FORM BY
HEAT, COLD OR REACTION WITH OTHER ELEMENTS    
112 ELEMENTS 92 NATURAL
20 LAB CREATION
5
PERIODIC TABLE
6
ATOM COMPOUND
ATOM SMALLEST PARTICLE OF AN ELEMENT   ATOMS
OF AN ELEMENT ARE ESSENTIALLY IDENTICAL ATOMS
OF ONE ELEMENT DIFFER FROM ATOMS OF EVERY OTHER

ELEMENT   COMPOUNDS ONE OR MORE ELEMENTS
COMBINE IN SPECIFIC
PROPORTIONS TO FORM CHEMICAL COMPOUNDS   EX
QUARTZ Si O2 (ONE Si ATOM 2 OXYGEN
ATOMS)   18 O, 17 O, 16 O
ISOTOPES OF OXYGEN ( STABLE ISOTOPES)  
RADIOACTIVE ISOTOPES ------- 232U92 ,
14C6
7
ENERGY LEVEL
ENERGY LEVEL SPECIFIC REGION OF SPACE AROUND THE
NUCLEUS WHERE
AN ELECTRON MOVES.   ELECTRONS FILL THE LOWEST
ENERGY LEVELS BEFORE THEY START FILLING HIGHER
LEVELS   --- LOWEST ENERGY LEVEL 2
ELECTRONS --- NEXT ENERGY LEVEL
8ELECTRONS --- NEXT ENERGY LEVEL 8
ELECTRONS --- NEXT ENERGY LEVEL
18ELECTRONS     BONDING ATOMS COMBINE TO FORM
CHEMICAL COMPOUNDS IN A
VARIETY OF WAYS KNOWN AS BONDING.  
8
ENERGY LEVEL DIAGRAM-H ATOM
9
ENERGY-LEVEL DIAGRAM He ATOM
10
ENERGY-LEVEL DIAGRAM Li ATOM
11
ENERGY-LEVEL DIAGRAM Na ATOM
12
IONS
IONS ELECTRICALLY CHARGED PARTICLE  
IONIC BONDING METALLIC BONDING
COVALENT BONDING
INTERMOLECULAR BONDING   TWO FACTORS THAT
DETERMINE WHICH ATOMS WILL UNITE WITH OTHERS  
1.EACH ATOM SHOULD ACHIEVE CHEMICAL
STABILITY   2.RESULTING COMPOUND SHOULD
BE NEUTRAL.
13
OCTET RULE
WHEN OUTER-MOST ENERGY LEVEL IS FILLED,
CHEMICAL STABILITY IS ATTAINED   OCTET RULE 8
ELECTRONS IN THE OUTERMOST ENERGY
LEVEL.   ATOMS BIND WITH OTHER ATOMS BY LOSING,
GAINING OR SHARING OUTER ELECTRONS   --------
ATOMS WITH 1 OR 2 ELECTRONS, TEND TO GIVE
UP -------- ATOMS WITH 6 OR 7 ELECTRONS, TEND
TO ACCEPT -------- ATOMS WITH 3 OR 4 OR 5
ELECTRONS, TEND TO SHARE INERT
GAS  
14
IONIC AND COVALENT BONDING 

• ? ION
• ? STRONG TENDENCY TO LOSE ELECTRONS/ STRONG
• TENDENCY TO GAIN ELECTRONS ?
  IONIC BONDING
•  
• COVALENT BONDING
•  
• SHARING OF ELECTRONS
• ATOMS WITH 3, 4, OR 5 ELECTRONS SHARE WITH
  OTHER
• SIMILARLY EQUIPPED ATOMS
• COVALENT BONDS ARE GENERALLY STRONGER THAN ANY
• OTHER BOND
•  

15
IONIC BONDING
16
METALLIC INTERMOLE. BONDING
METALLIC BONDING ATTRACTION OF NEGATIVELY
CHARGED ELECTRON CLOUD TO A CLUSTER OF
POSITIVELY CHARGED NUCLEI.   INTERMOLECULAR
BONDING WEAK BONDING BETWEEN MOLECULES DUE
TO UNEVEN DISTRIBUTION OF ELECTRONS.  
17
HYDROGEN BOND
POSITIVE CHARGE OF OXYGEN ATOM gt HYDROGEN
ATOM --- SHARED ELECTRONS ARE MORE ATTRACTED
TO THE OXYGEN NUCLEUS ---- OXYGEN SIDE DEVELOPS
A WEAK NEGATIVE CHARGE A WEAK POSITIVE CHARGE
IN H SIDE

• WEAKLY CHARGED REGIONS ATTRACT OPPOSITELY CHARGED
  REGIONS OF NEARBY MOLECULES HYDROGEN BONDS
• H2O NaCl ----------gt Na Cl-
• MANY MINERALS HAVE SAME QUALITIES AS MOLECULES
• MINERALS MAY BE SUBJECT TO INTERMOLECULAR BONDS
• WEAK INTERMOLECULAR ATTRACTION VAN DER WAALS
  BOND
•  

18

• Summary on Bonding
• Ionic bonding
• Involves transfer of valence electrons from one
  atom to another
• Covalent bonding
• Involves sharing of valence electrons among
  adjacent atoms
• Metallic bonding
• Electrons flow freely throughout metals results
  in high electrical conductivity

19
MINERAL STRUCTURE

• CRYSTALS ---- A REGULAR GEOMETRIC SHAPE
• CRYSTAL STRUCTURE ---- ORDERLY ARRANGEMENT
• OF IONS OR ATOMS INTO A LATTICE WORK OF
• REPEATED THREE DIMENSIONAL UNITS
• GLASS IS NOT A MINERAL SUDDEN COOLING OF
• MOLTEN ROCK RESULTS IN LACK OF ORDERLY
• ARRANGEMENT
• MINERALOIDS CONSTANT COMPOSITION BUT, NO
• SPECIFIC
  CRYSTAL STRUCTURE
• EX
  OBSIDIAN ( A NATURAL GLASS )
•  

20
NaCl STRUCTURE
21
MINERALS DEPEND ON
MINERALS AT ANY TIME SPACE DEPENDS ON
  ELEMENTS AVAILABLE TO BOND CHARGES AND
SIZES OF IONS TEMPERATURE AND PRESSURE AT WHICH
MINERALS FORM ------ IONS ATOMS OF SIMILAR
SIZE CHARGE ARE ABLE TO REPLACE ONE ANOTHER
WITHIN A CRYSTAL STRUCTURE --- IONIC
SUBSTITUTION EX Sr IN CaCO3 MINERAL
Ba, Sr IN FORAM, INORGANIC CARBONATE.
22
GRAPHITE STRUCTURE
23
DIAMOND STRUCTURE
24
ELEMENTAL ABUNDANCE
25
POLYMORPHISM
IONIC SUBSTITUTION CERTAIN IONS OF SIMILAR SIZE
AND CHARGE REPLACE ONE ANOTHER WITHIN A CRYSTAL
STRUCTURE, DEPENDING ON WHICH IS MOST AVAILABLE
DURING THE MINERALS FORMATION EX
Sr 2 IN CaCO3 (RAPLACING Ca )
Fe 2 AND Mg 2 IN OLIVINE ( Fe, Mg )2 SiO4

  POLYMORPHISM SAME CHEMICAL COMPOSITION BUT
DIFFERENT PHYSICAL STRUCTURE ( DIFF PHYSICAL
PROPERTIES)   POLY MANY MORPH FORMS OR
STRUCTURES   EX GRAPHITE AND DIAMOND
ARAGONITE AND CALCITE
26
DIAMETERS OF IONS
27
MINERAL IDENTIFICATION

• FIELD
• LABORATORY
•  
• COLOR LEAST RELIABLE IDENTIFYING CHARACTERISTIC
• LUSTER DESCRIBES HOW A MINERALS SURFACE
  REFLECTS LIGHT
• ( VIBRATING ELECTRONS EMIT A
  DIFFUSE LIGHT, GIVING
• METALLIC SURFACES THEIR CHARACTERISTIC
  SHINY LUSTER)
•  
• STREAK COLOR OF A MINERAL IN ITS POWDERED FORM
  OFTEN A
• MORE ACCURATE INDICATOR OF
  MINERAL IDENTITY.
•  

28
MOHS SCALE
HARDNESS MINERALS RESISTANCE TO SCRATCHING OR
ABRASION MINERALS HARDNESS INDICATES THE
RELATIVE STRENGTH OF ITS BONDS   MOHS HARDNESS
SCALE ASSIGNS RELATIVE HARDNESSES TO SEVERAL
COMMON AND A FEW RARE AND PRECIOUS MINERALS  
29
 MOHS HARDNESS SCALE
30
SCALE-CONTD.
FINGER NAIL 2.5 GLASS 5-6 STEEL FILE 6.5
31
CLEAVAGE
CLEAVAGE TENDENCY OF A MINERAL TO BREAK
CONSISTENTLY ALONG DISTINCT PLANES IN THEIR
CRYSTAL STRUCTURES WHERE THE BONDS ARE WEAKEST,
OR FEWER IN NUMBER   TWO MINERALS THAT ARE
SIMILAR IN EXTERNAL FORM, HARDNESS AND OTHER
CHARACTERISTICS MAY HAVE DIFFERENT CLEAVAGE
PLANES   FRACTURE WHEN BONDS ARE EQUALLY STRONG
IN ALL DIRECTIONS AND DISTRIBUTED UNIFORMLY
MINERALS DO NOT CLEAVE THEY FRACTURE AT
RANDOM   EXAMPLE QUARTZ ALL ATOMS BOND
COVALENTLY  
32
SMELL TASTE
SMELL TASTE HALITE SALTY   KCl BITTER  
SULFUR CONTAINING MINERALS H2S
SMELL   EFFERVESCENCE CaCO3 HCl ---------gt
EFFERVESCENCE NaCl HCl ---------gt NO
EFFERVESCENCE     CRYSTAL FORM SHAPE OF A WELL
FORMED CRYSTAL MAY BE DISTINCTIVE ENOUGH TO
IDENTIFY THE MINERAL
33
LABORATORY   SPECIFIC GRAVITYSUBSTANCE WEIGHT
/WEIGHT OF EQUAL VOLUME OF
H2O
DENSITY MASS (G) / VOLUME
(CM3)   POLYMORPHS HAVE SLIGHTLY DIFFERENT
DENSITIES   EX GRAPHITE 2.3 DIAMOND 3.5
(COMPRESSED CRYSTAL STRUCTURE)
  OTHER LAB TESTS   BY TRANSMITTED
LIGHT THROUGH A THIN SECTION UNDER UV CERTAIN
MINERALS GLOW FLUORESCENCE PHOSPHORESCENCE
GLOW AFTER UV LIGHT IS REMOVED  
34

• ROCK FORMING MINERALS
•  
• FIVE GROUPS OF MINERALS
• SILICATES ( Si, O 1 OR 2 COMMON ELEMENTS)
• CARBONATES (C, Ca, O)
• OXIDES
• SULFATES
• SULFIDES

35

Silicate Structures

• The Silicon-Oxygen tetrahedron
• Strongly bonded silicate ion
• Basic structure for silicate minerals
• Sharing of O atoms in tetrahedra
• The more shared O atoms per tetrahedron, the more
  complex the silicate structure
• Isolated tetrahedra (none shared)
• Chain silicates (2 shared)
• Double-chain silicates (alternating 2 and 3
  shared)
• Sheet silicates (3 shared)
• Framework silicates (4 shared)

36

• IN CRUST gt 1000 DIFF SILICATE MINERALS
• FIVE MAJOR PRINCIPAL CRYSTAL STRUCTURE
•  
• INDEPENDENT
  TETRAHEDRA
• SINGLE CHAINS
• DOUBLE CHAINS
• SHEET
• 3-D FRAMEWORK

37
.
Non-silicate Minerals

• Carbonates
• Contain CO3 in their structures (e.g., calcite -
  CaCO3)
• Sulfates
• Contain SO4 in their structures (e.g., gypsum -
  CaSO4. 2H2O)
• Sulfides
• Contain S (but no O) in their structures (e.g.,
  pyrite - FeS2)
• Oxides
• Contain O, but not bonded to Si, C or S (e.g.,
  hematite - Fe2O3)
• Native elements
• Composed entirely of one element (e.g., diamond -
  C gold - Au)

38
DRY CLAY MINERAL STRUC
39
EXPANSION DUE TO ADSOR
40
NAMING A MINERAL 40 NEW
MINERALS/YEAR gt3000 MINERALS KNOWN
GEOGRAPHICAL LOCATION
DISTINCT PHYSICAL CHARACTERISTIC
CHEMICAL FORMULA BASED NAME WOULD NOT WORK
POLYMORPHISM EXISTENCE  
41

Minerals

• A mineral must meet the following criteria
• Crystalline solid
• Atoms are arranged in a consistent and orderly
  geometric pattern
• Forms through natural geological processes
• Has a specific chemical composition
• Rock-forming minerals
• Although over 4000 minerals have been identified,
  only a few hundred are common enough to be
  generally important to geology (rock-forming
  minerals)
• Over 90 of Earths crust is composed of minerals
  from only 5 groups (feldspars, pyroxenes,
  amphiboles, micas, quartz)

42
Geology at a Glance (continued).
43

CHAPTER-2
SUMMARY   DEFINITION OF A MINERAL,
ROCK DEFINITION OF MINERALOIDS OPAL,
GLASS ATOMIC MASS, ATOMIC WEIGHT,
ISOTOPE WHAT DETERMINES WHETHER AN ATOM WILL
BIND ANOTHER ATOM IONIC BOND COVALENT
BOND METALLIC BOND HYDROGEN BOND
44
VAN DER WALLS BOND POLYMORPHISM BEST SINGLE
PROPERTY TO IDENTIFY MINERALS OTHR MINERAL
IDENTIFICATION TECHNIQUES MINERAL
HARDNESS SPECIFIC GRAVITY MOST ABUNDANT
MINERAL GROUP QUARTZ CONSTITUENTS
STRUCTURE NAMING OF MINERALS