Lecture 3.  Orders of magnitude
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Lecture 3. Orders of magnitude From planets to atoms. Example of coordination number. SiO 2 CN Si = 4. Atomic and ionic radii In picometers (pm). How big is an atom? ~100 picometers (pm) or ~1 Angstrom. Lengthscales in nature span more than 27 orders of magnitude.

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Lecture 3. Orders of magnitude From planets to atoms

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Lecture 3 orders of magnitude from planets to atoms

Lecture 3. Orders of magnitude

From planets to atoms


Lecture 3 orders of magnitude from planets to atoms

Example of coordination number

SiO2

CNSi = 4


Lecture 3 orders of magnitude from planets to atoms

Atomic and ionic radii

In picometers (pm)


Lecture 3 orders of magnitude from planets to atoms

How big is an atom?

~100 picometers (pm) or ~1 Angstrom


Lecture 3 orders of magnitude from planets to atoms

Lengthscales in nature span more than 27 orders of magnitude

Diameter of Milky Way Galaxy100 kilo-lightyears

Distance to Neptune from Earth4.3 x 109 km

Radius of Sun7 x 105 km

Radius of Earth6.37 x 103 km

Thickness of Earth’s continental crust3.2 x 101 km

Depth of oceans4 km

Deepest hole drilled into the Earth10 km

Tallest building on Earth1.3km

Length of a soccer field109.7m

Diameter of soccer ball0.22 m

Dimensions of soccer goal2.44 by 7.135 m

Size of an ant1 mm

Size of an atom0.1 nm

1 lightyear = 9.46 x 1015 m


Orders of magnitude

Orders of magnitude

1,250,000

is

1.25 x 106

or 1.25 billion

Numbers can be converted to scientific notation

The base 10 logarithm (or log10) gives you the order of magnitude of that number

For example…

log10(1,250,000) = log10(1.25 x 106)

= log10(1.25) + log10(106)

= log10(1.25) + 6

Since log10(1) = 0, we say that 1,250,000 is on the order of 1 million (106)


Metric system units

Metric system units

[LENGTH]

km

m

cm

mm

μm

nm

pm

kg

g

mg

μg

ng

pg

=103 m

=100 m

=10-2 m

=10-3 m

=10-6 m

=10-9 m

=10-12 m

=103 g

=100 g

=10-3 g

=10-6 g

=10-9 g

=10-12 g

[MASS]

Do not confuse metric units with miles, inches, or pounds.


Lecture 3 orders of magnitude from planets to atoms

Rough diamonds

Kimberly diamond mine in S Africa

Diamond mine NWT, Canada


Lecture 3 orders of magnitude from planets to atoms

Gypsum CaSO4(H2O)2

Gypsum crystals from a Lead mine in Mexico


Lecture 3 orders of magnitude from planets to atoms

Z = Proton Number

N = number of neutrons

A = Atomic Mass Number

= Z + N

An element is defined by its proton number

Number of protons and electrons dictates chemical behavior of atom


Lecture 3 orders of magnitude from planets to atoms

Electronegativity

Tendency for an atom to attract an electron in a molecule


Lecture 3 orders of magnitude from planets to atoms

Chemical bonding

Similar electronegativity

Contrasting electronegativity

Covalent bonds tend to be stronger than ionic bonds


Lecture 3 orders of magnitude from planets to atoms

Al

1.41

Ca

1.54

?

2.9

Ni

1.8

Fe

32.1

O

30.1

Si

15.1

Mg

13.9

BULK EARTH


Lecture 3 orders of magnitude from planets to atoms

Majority of earth materials are made up of silicates

Silicates are mineral compounds that have silica tetrahedra as their basic building blocks, e.gSiO4-4

Si-O bond is dominantly covalent


Lecture 3 orders of magnitude from planets to atoms

Quartz

SiO2

Silica tetrahedra are linked at all apices

Fully polymerized

One of the most common minerals in the continents


Lecture 3 orders of magnitude from planets to atoms

[SiO4]4- Independent tetrahedraNesosilicates

Olivine

Mg2SiO4

(aka peridot)

Abundant mantle mineral

Garnet

(Mg,Ca,Fe)3Al2Si3O12

Common crustal mineral


Lecture 3 orders of magnitude from planets to atoms

Nesosilicates: independent SiO4tetrahedra

OLIVINE

SiO4tetrahedra are not linked to each other

-separated by Mg2+cations that are ionically bonded to O2- apices of the silica tetrahedra

Olivine (100) view blue = M1 yellow = M2

http://www.whitman.edu/geology/winter/


Lecture 3 orders of magnitude from planets to atoms

Peridotite

An olivine-rich rock that makes up much of the mantle


Lecture 3 orders of magnitude from planets to atoms

n[SiO3]2-n = 3, 4, 6 Cyclosilicates

Examples: benitoiteBaTi[Si3O9]

axiniteCa3Al2BO3[Si4O12]OH

beryl Be3Al2[Si6O18]

tourmaline CaMg3Al6(BO3)3(Si6O18(OH)4

Beryl with charge transfer = aquamarine

Beryl with Cr = Emerald

tourmaline

http://www.whitman.edu/geology/winter/


Lecture 3 orders of magnitude from planets to atoms

PYROXENES

Spodumene

(kunzite)

LiSiO3

[SiO3]2- single chains

pyroxenes pyroxenoids

Dark green mineral in peridotite

Diopside

CaMgSi2O6

Common mineral in the mantle


Lecture 3 orders of magnitude from planets to atoms

Amphiboles

Hornblende

(Ca,Na)2–3(Mg,Fe,Al)5(Al,Si)8O22(OH,F)2

[ [Si4O11]4- Double tetrahedra

amphiboles

One of the common “black” minerals in granitoids


Lecture 3 orders of magnitude from planets to atoms

Phyllosilicates

Micas and clays

[Si2O5]2- Sheets of tetrahedra Phyllosilicates

micas talc clay minerals serpentine

http://www.whitman.edu/geology/winter/


Lecture 3 orders of magnitude from planets to atoms

Biotite

K(Mg,Fe)3(AlSi3O10)(F,OH)2

Common “black” mineral in granitoids

Differs from hornblende in being flaky and sheet-like


Lecture 3 orders of magnitude from planets to atoms

Tectosilicates

Feldspars and quartz

low-quartz

[SiO2] 3-D frameworks of tetrahedra: fully polymerized Tectosilicates

quartz and the silica minerals feldspars feldspathoids zeolites

http://www.whitman.edu/geology/winter/


Lecture 3 orders of magnitude from planets to atoms

FELDSPARS

Plagioclase

CaAlSSi2O8

Orthoclase

(K,Na)AlSi3O8

Common minerals in granitic rocks

The precursor of clays used in ceramics


What did we learn today

What did we learn today

  • Concepts of orders of magnitude

  • Chemical Bonding

  • Basic minerals on Earth

Next lecture – physical properties of rocks and minerals


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