Introduction to Chemistry

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Introduction to Chemistry Background for
Nanoscience and Nanotechnology

• Prof. Petr Vanysek

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Introduction to Chemistry Principles
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Introduction to measurements

• Introduction to measurements
• Distance/size
• dynamics of the scale from the wavelength of
  x-rays to astronomic distances.
• focus on the middle scale size from visible
  objects person, hand (where did inch come
  from?), fingernail thickness, hair diameter,
  mite, microbe, virus, finally atom and a
  molecule.

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Wide range of dimensions

• Electromagnetic spectrum

Relevant dimensions kilometers (103
m) meters centimeters (2-1/2 1
inch) millimeter nanometers Angstroms (10-10
m) size of an atom
Atom Electrons going around the nucleus
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Units of Measurement

• SI Units
• There are two types of units
• fundamental (or base) units
• derived units.
• There are 7 base units in the SI system.

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Units of Measurement
Base SI Units
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Units of Measurement
SI Units
Selected Prefixes used in SI System
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Units of Measurement

• SI Units
• Note the SI unit for length is the meter (m)
  whereas the SI unit for mass is the kilogram
  (kg).
• 1 kg weighs 2.2046 lb.
• Temperature
• There are three temperature scales
• Kelvin Scale
• Used in science.
• Same temperature increment as Celsius scale.
• Lowest temperature possible (absolute zero) is
  zero Kelvin.
• Absolute zero 0 K -273.15 oC.

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Measurements - Distance

• Standard units
• length
• Meter (a little more than 3 feet)
• too large for some purpose
• millimeter, centimeter
• (multiples of 10, e.g., 1 meter 1000 cm)
• Inch nonstandard unit, thumb (sp.
  thumbpulgar, inchpulgada, greek
  inchdaktulosfinger)

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Why dimensions matter? Nanomaterials particles
of nanometer size
Nano-scale materials often have very different
properties from bulk materials e.g. color and
reactivity

• 3nm iron particle has 50 of atoms on the
  surface
• 10nm particle has 20 of atoms on the surface
• 30nm particle has 5 of atoms on the surface

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The scale of things
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Squared and cubed distance

• Area distance squared
• Volume distance cubed

the liter is a basic volume unit in chemistry, is
is one decimeter cubed, of 10x10x101000 cm
cubed. It is somewhat larrer than one quart
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Units of Measurement
Volume

• The units for volume are given by (units of
  length)3.
• SI unit for volume is 1 m3.
• We usually use 1 mL 1 cm3.
• Other volume units
• 1 L 1 dm3 1000 cm3 1000 mL

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Concentration

• Amount per volume
• grams per liter
• moles per liter

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Amount of material

• mass in kilograms or in grams
• count of particles
• 12 dozen
• 500 ream
• 6.022 x 1023 mole

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Temperature

• Vigor of movement of paticles atoms or
  molecules.
• Scientific units Degrees Celsius (water freezes
  at zero and boils at hundred.
• Kelvin same spacing as Celsius, starts at
  absolute zero and 0 oC is 273.15 K.

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Change of volume with temperature

• Thermal expansion volumetric thermal expansion.

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Mercury thermometer
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Conversion of temperature units

• Some units need to be converted, e.g.,
  centimeters to inches, which is simple
  multiplication.
• Lcm 2.54Lin
• Temperature conversiton Fahrenheit to Celsius is
  a bit more involved
• Tc (5/9)(Tf-32)
• Tf ((9/5)Tc)32

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Large dynamic range of dimensions
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Forms of materialDIAMOND - GRAPHITE
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Forms of materialCARBON - GRAPHITE
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Form of materialGRAPHITE - FULLERENE
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Fullerenes
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Fullerenes
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Acceptance of nanotechnology
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Why Study Chemistry?

• Chemistry is the study of the properties of
  materials and the changes that materials undergo.
• Chemistry is central to our understanding of
  other sciences.
• It is substantial part of nanoscience and
  nanotechnology

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The Study of Chemistry

• The Molecular Perspective of Chemistry
• Matter is the physical material of the universe.
• Matter is made up of relatively few elements.
• On the microscopic level, matter consists of
  atoms and molecules.
• Atoms combine to form molecules.
• As we see, molecules may consist of the same type
  of atoms or different types of atoms.

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Molecular Perspective of Chemistry
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Classification of Matter

• States of Matter
• Matter can be a gas, a liquid, or a solid.
• These are the three states of matter.
• Gases take the shape and volume of their
  container.
• Gases can be compressed to form liquids.
• Liquids take the shape of their container, but
  they do have their own volume.
• Solids are rigid and have a definite shape and
  volume.

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Classification of Matter

• Pure Substances and Mixtures
• Elements consist of a unique type of atom.
• Molecules can consist of more than one type of
  element.
• Molecules that have only one type of atom (an
  element).
• Molecules that have more than one type of atom (a
  compound).
• If more than one atom, element, or compound are
  found together, then the substance is a mixture.

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• Pure Substances and Mixtures

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Classification of Matter

• Pure Substances and Mixtures
• If matter is not uniform throughout, then it is a
  heterogeneous mixture.
• If matter is uniform throughout, it is
  homogeneous.
• If homogeneous matter can be separated by
  physical means, then the matter is a mixture.
• If homogeneous matter cannot be separated by
  physical means, then the matter is a pure
  substance.
• If a pure substance can be decomposed into
  something else, then the substance is a compound.

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Classification of Matter

• Elements
• If a pure substance cannot be decomposed into
  something else, then the substance is an element.
• There are 114 elements known.
• Each element is given a unique chemical symbol
  (one or two letters).
• Elements are building blocks of matter.
• The earths crust consists of 5 main elements.
• The human body consists mostly of 3 main
  elements.

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Classification of Matter

• Elements

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Classification of Matter

• Elements
• Chemical symbols with one letter have that letter
  capitalized (e.g., H, B, C, N, etc.)
• Chemical symbols with two letters have only the
  first letter capitalized (e.g., He, Be).

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Classification of Matter

• Compounds
• If water is decomposed, then there will always be
  twice as much hydrogen gas formed as oxygen gas.
• Pure substances that cannot be decomposed are
  elements.
• Mixtures
• Heterogeneous mixtures are not uniform
  throughout.
• Homogeneous mixtures are uniform throughout.
• Homogeneous mixtures are called solutions.

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Properties of Matter

• Physical vs. Chemical Properties
• Physical properties can be measure without
  changing the basic identity of the substance
  (e.g., color, density, odor, melting point)
• Chemical properties describe how substances react
  or change to form different substances (e.g.,
  hydrogen burns in oxygen)
• Intensive physical properties do not depend on
  how much of the substance is present.
• Examples density, temperature, and melting
  point.
• Extensive physical properties depend on the
  amount of substance present.
• Examples mass, volume, pressure.

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Properties of Matter
Physical and Chemical Changes
2 H2 O2 ? 2 H2O
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Properties of Matter

• Physical and Chemical Changes
• When a substance undergoes a physical change, its
  physical appearance changes.
• Ice melts a solid is converted into a liquid.
• Physical changes do not result in a change of
  composition.
• When a substance changes its composition, it
  undergoes a chemical change
• When pure hydrogen and pure oxygen react
  completely, they form pure water. In the flask
  containing water, there is no oxygen or hydrogen
  left over.

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Review of Chemistry

• States of Matter
• Atoms, Molecules and Ions
• Subatomic particles
• Periodic Table
• Covalent and ionic bonding
• Chemical reactions
• Inter-molecular forces

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States of Matter
Solid Keeps shape Keeps volume Salt, gold, copper
Liquid Takes shape of container Keeps volume Water, alcohol, oil
Gas Takes shape of container Takes volume of container Air, argon, helium, methane
Plasma like a gas of charged particles. Takes shape of container Takes volume of container Stars, nebula, lightning, plasma reactors
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Matter

• Solution A uniform mixture of two substances
  such that molecules are separate from each other
  and move around randomly. Usually these are
  liquids. Solutions are usually transparent.
• Colloids A mixture of much larger particles
  ranging from 20 nm to 100 µm. Milk and paint are
  colloids.
• Grains Some materials are made up of many small
  crystals called grains. A grain is an individual
  crystal of such a solid. Different grains may
  have the crystal lattice oriented in different
  directions.

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Grain Structure in Steel
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Elements, Atoms and Molecules

• Atoms All matter is made up of tiny particles
  called atoms.
• Molecules Sometimes two or more atoms are found
  bound together to form molecules.
• The atoms can be categorized into about 115
  different types based on the charge of the
  nucleus.
• Elements are made up of only one type of atom.
• The element carbon takes the form of graphite,
  diamond and buckminsterfullerene as well as
  others.
• It is only possible to change one type of atom
  into another through nuclear processes such as
  take place in a nuclear power plant, the sun,
  atomic bombs or particle accelerators.
• The elements do not change in ordinary chemical
  reactions.

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The Periodic Table
1 H 2 He
3 Li 4 Be 5 B 6 C 7 N 8 O 9 F 10 Ne
11 Na 12 Mg 13 Al 14 Si 15 P 16 S 17 Cl 18 Ar
19 K 20 Ca 21 Sc 22 Ti 23 V 24 Cr 25 Mn 26 Fe 27 Co 28 Ni 29 Cu 30 Zn 31 Ga 32 Ge 33 As 34 Se 35 Br 36 Kr
37 Rb 38 Sr 39 Y 40 Zr 41 Nb 42 Mo 43 Tc 44 Ru 45 Rh 46 Pd 47 Ag 48 Cd 49 In 50 Sn 51 Sb 52 Te 53 I 54 Xe
55 Cs 56 Ba 57 La 72 Hf 73 Ta 74 W 75 Re 76 Os 77 Ir 78 Pt 79 Au 80 Hg 81 Tl 82 Pb 83 Bi 84 Po 85 At 86 Rn
87 Fr 88 Ra 89 Ac 104 Rf 105 Db 106 Sg 107 Bh 108 Hs 109 Mt 110 Ds 111 112 113 114 115 116 117 118

58 Ce 59 Pr 60 Nd 61 Pm 62 Sm 63 Eu 64 Gd 65 Tb 66 Dy 67 Ho 68 Er 69 Tm 70 Yb 71 Lu
90 Th 91 Pa 92 U 93 Np 94 Pu 95 Am 96 Cm 97 Bk 98 Cf 99 Es 100 Fm 101 Md 102 No 103 Lr
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Subatomic Particles

• Most of matter is made of three subatomic
  particles

Particle Symbol Relative Charge Relative Mass Location
Electron e- -1 1 Electron Cloud
Proton p 1 1836 Nucleus
Neutron n0 0 1839 Nucleus
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Ions

• Usually atoms have the same number of electrons
  as protons so the charges cancel each other out.
• Sometimes an atom can have more or fewer
  electrons than protons resulting in a net
  positive or negative charge. When this happens
  it is called an ion.
• Example Na loses an electron to form Na
• Chlorine can gain an electron to from Cl-
• We can tell what type of charge an ion is
  expected to have by looking at where it is in the
  periodic table.

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Isotopes

• Atoms with the same number of protons but
  different numbers of neutrons
• Deuterium, tritium, carbon 12, U235
• Some isotopes are radioactive while others are
  stable