Testing

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Elements

• Definition - Elements contain only one type of
  atom
• 90 naturally occuring elements (92 heaviest nat.
  occuring)
• Transuranium elements - synthetic
• Types of elements
• a) Monoatomic Fe, Au
• b) Molecular H2, N2, O2, P4, C60

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Origin of the Elements
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Origin of the Elements
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Origin of the Elements

• Big Bang produced H and He
• Clouds of dust form stars
• Young stars fuse H to He (stellar fusion)
• Older stars make up to Fe
• Supernova produce up to U and scatter a lot of
  dust

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Supernova Remnant
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Origin of the Elements

• Abundance (by mass)
• Earths Crust 49 O
• Body 65 O
• Universe 90 H and 10 He

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History The Atom

• Democritus
• 1. Atomos Indivisible (400 B.C.)
• 2. Smallest particle of a substance that retains
  the properties of that substance
• 3. Only Atoms and the Void
• 4. Aristotle had a competing theory that was
  accepted (nature abhors a vacuum)

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History The Atom

• John Dalton
• Proposed atomic theory in 1803
• Thought of atoms like pool balls

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History The Atom

• 3. Atomic Theory
• a. All matter is made of indivisible
• particles called atoms
• b. Atoms of same element have same
• properties
• c. Atoms combine in small, whole
• ratios
• d.Chemical reactions are merely the
• rearrangement of atoms

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Symbols for Elements

• Symbols
• a. Jons Berzelius standardized the names and
  symbols of the elements
• b. Strontium Sr

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Names for Elements

• a. Greek Latin
• Na Natrium
• K Kalium
• Li Lithos
• b. Places (Ge, Fr, Cf)
• Y, Yb, Er, Tb Ytterby
• c. Scientists (Es, Fm, Cm)

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History The Electron

• J.J. Thomson (1897) discovered the electron
  with a Cathode Ray Tube

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History The Electron
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History The Electron
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History The Electron
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History The Electron
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History The Electron
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History The Electron

• b. Conclusions
• 1) Negatively charged
• (went to anode, positive plate)
• 2) Not light Bent by
• charged plates (or magnets)

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History The Electron

• Thomson Plum Pudding Model
• a. Drawing
• b. Began search for
• the positive electron

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• Electrons move in the atom at about
• 5 MILLION MILES PER HOUR!!

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History The Nucleus

• Rutherford (1911)
• Succeeded Thomson at Cambridge University.
• Gold Foil Experiment

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History The Nucleus
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• 18000 bounced back.
• Alpha particles travel at 10,000 miles/s
• NONE should have bounced back

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History The Nucleus
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History The Nucleus

• 3. Results
• a. Nucleus is heavy and dense
• b. 99.9 of atoms mass is in the nucleus
• c. Electrons orbit the nucleus
• d. Most of the atom is empty space

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History The Proton

• Rutherford (1914)
• Had been suspected to exist since 1886
  (Goldsteins canal rays)
• 1836 times heavier than the electron

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History The Neutron

• Discovered last (1932) by Chadwick
• Difficult to find because it has no charge
• Roughly same mass as proton

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The Worlds Most Famous Neutron
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Quarks

• Quarks particles that compose protons and
  neutrons
• Murray Gell-Mann (1968)
• May be the smallest particles in the universe
• 6 Flavors
• Up (2/3) Down (-1/3)
• Top Bottom
• Strange Charm

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Quarks

• Proton ? 2up 1down
• Neutron? 1up 2down
• An electron is NOT made of Quarks!

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History The Atom

• Scanning Tunneling Microscope - allows us to take
  pictures of the atoms
• Proof for the existence of atoms

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History The Atom
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History The Atom
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Photo of a single Barium atom
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Protons, Neutrons and Electrons

• Make up the atom
• Example Lithium (do drawing)
• 3 9
• Li F
• 6.941 18.994

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Isotopes

• 1. Carbon example
• Atomic protons
• Atomic Mass p n
• Isotopes Atoms with the same of protons, but
  different of neutrons
• Elements often exist as a mixture of isotopes
• Copper-63
• Copper-65

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Isotopes

• 4. Examples

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Isotopes

• Cancer treatment (60Co gives off gamma rays)
• Medical Tracers (24Na for circulatory system)
• 14C dating
• a. Mummies
• b. Shroud of Turin
• 4. Nuclear fuel (235U and 239Pu)

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Ions

• Cation positive ion (more p than e)
• Anion Negative ion (more e than p)

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Ions
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Isotopes

• Some isotopes are more common
• Hydrogen example
• 1H
• 2H (deuterium)
• 3H (tritium)
• 3. Atomic Mass Weighted Average of all the
  isotopes

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Average Atomic Mass

• 4. What is the ave atomic mass of Gallium if it
  exists as 60.30 69Ga (68.926 g/mol) and 39.70
  71Ga (70.926 g/mol)?
• (Ans 69.72 g/mol)

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Average Atomic Mass

• 5. Out of 400 chlorine atoms, 302 are 35Cl
  (34.969 g/mol), and 98 are 37Cl (36.966 g/mol).
  Average atomic mass?

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Average Atomic Mass

• What is average atomic mass of Copper if 69.09
  exists as 63Cu (62.9298 g/mol) and the rest
  exists as 65Cu (64.9278 g/mol)?
• ANS(63.55 g/mol)

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• Warm-Up Group the following
• Au H2O O2
• C P4 P2O5
• Be N2 C2H4
• C60 NH3 Cl2
• Te S8 C6H12O6

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Compounds

• Definition - Composed of two or more different
  elements
• Examples
• H2O, CH4, NaCl, Fe2(SO4)3
• Are there more elements or compounds?
• Elements letters
• Compounds - words

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What is a Molecule?

• Group of atoms held together by covalent and
  polar covalent bonds (SHARING)
• Usually composed of non-metals
• Separate (discrete) groups of atoms
• Examples H2, P4, CH4

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Diatomic Molecular Elements

• H2 Hydrogen
• N2 Nitrogen
• O2 Oxygen
• F2 Fluorine
• Cl2 Chlorine
• Br2 Bromine
• I2 Iodine

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Diatomic Elements
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Diatomic Elements
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What is an Ionic Compound?

• Usually start with a metal atom
• Composed of ions (wanderer) No sharing but
  stealing.
• cation positive ion
• anion negative ion
• Example NaCl, CaCl2, Na2SO4
• Formula Unit instead of molecule

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• 1. Are the following ionic or molecular?
• HCl CO2 VO3
• H2O BaF2
• 2. Write the formula for the compound that forms
  between
• Na and O2-, Al3 and O2-
• K and PO43-, Ba2 and NO3-

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The Key to the Universe
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Measuring
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Measuring
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Measuring
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• I would measure with a ruler with more marks to
  get more significant figures.
• More supplies would make the experiment go
  faster.
• The metal pieces should be allowed to carefully
  slide down the side of the cylinder. This would
  prevent splashing of the water. The splashing
  seen in this experiment probably resulted in a
  smaller volume for the metal pieces.
• I would do more trials to get more numbers.
  This should give a more accurate average.

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