Atomic Structure

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Atomic Structure

• Modern Theory

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Subatomic particles

• Protons
• Positively charged particle located in nucleus
• Mass 1.673 e 24 g or 1.0073 u
• Always moving (atomic vibration)
• Composed on 2 Up quarks and 1 Down

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More Subatomic Particles

• Neutrons
• Subatomic particle located in nucleus with no
  electrical charge
• Mass 1.675 e 24 g or 1.0087 u
• Decays into proton, electron, and electron
  anti-neutrino
• Composed of one Up quark and 2 Down

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More Subatomic Particles

• Electrons
• Very small negatively charged subatomic particle
  in orbit around nucleus
• Mass 1.1 E 29 g or 0.000 549 u
• Mass 1/1836 of proton
• Moves rapidly and is easily accelerated

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Nucleus

• Atom is between 10 and 100 000 times larger than
  nucleus
• Baseball stadium idea
• Bubble bees and hornets idea

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Definitions

• Leptons no perceptible internal structure with
  spin ½ (examples electron, neutrino, muon)
• Hadrons particles composed of quarks (examples
  protons, neutrons)
• Quarks building blocks of hadronic particles (in
  increasing size Up, Down, Charm, Strange, Top,
  Bottom)

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Matter vs Antimatter

• For every particle there is a corresponding
  antiparticle. These particles and antiparticles
  have identical mass and spin but opposite charges.

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Definitions

• Atomic Number (Z) number of protons in the
  nucleus (if atom is electrically balanced it will
  also be the of electrons)
• Atomic Mass (M) see definition in class
• Mass Number (A) sum of protons and neutrons in
  nucleus
• Nucleons particles that make up the nucleus of
  an atom

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More Definitions

• Element pure form of substance, made up of only
  one kind of atom -- elements are simple
  substances that cannot be decomposed or changed
  into another element by chemical means
• Atom smallest particle of element
• Molecule 2 or more atoms bonded chemically
  together, has a definite, invariable composition
  and structure

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Ions

• Ions are atoms that have lost or gained electrons
• Ca ? loses 2 electrons Ca2
• 20 p 20
  p
• 20 e-
  18 e-

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Isotopes

• Isotopes are atoms of the same element but with
  different number of neutrons
• (mass numbers will be different but atomic
  numbers will be the same)
• example Boron example given in class

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Hydrogen Isotopes

• Natural hydrogen (1 proton and 1 electron)
• Deuterium (1 proton, 1 electron, 1 neutron)
• Tritium (1 proton, 1 electron, 2 neutrons)

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Compounds

• Compounds are two or more elements chemically
  joined (held together by chemical bonds)
• There is a fixed proportion of elements by weight
• Properties are different from components
• Compounds can be separated only by chemical means

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Mixtures

• Mixtures are two or more substances (elements or
  compounds or both) that do not combine chemically
  during the mixing.
• There is a variable proportion of components
• Properties remain the same as before mixing
• Parts can be separated by physical means

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Mixture SubTypes

• Heterogeneous divide mixture into 2 halves and
  get different composition
• Homogeneous divide mixture into 2 halves and
  they are identical

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More Mixture types

• Emulsion mixture of 2 immiscible liquids (ones
  that dont mix), examples oil vinegar
  dressing, paint, hand crème
• Alloy mixture of 2 or more metals melted
  together having new and different properties,
  examples bronze, brass, pewter
• Amalgam mixture containing mercury

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Solutions

• A solution is a liquid homogeneous mixture
  containing a dissolved substance
• Solvent component in largest concentration
• Solute component in smallest concentration
• Aqueous solvent is water
• Tincture solvent is alcohol

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More on Solutions

• Dilute solutions small amount of solute compared
  to amount of solvent
• Concentrated solution contains more solute than
  a dilute solution
• Saturated solution when solvent cannot hold any
  more solute at a given temperature

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Types

• Suspension heterogeneous mixture where visible
  particles will settle out
• Colloids particles small enough that they do not
  settle out and are usually too small to be
  visible (examples gelatin, cold cream,
  lipstick, shaving cream)
• Emulsion colloid of 2 liquids (examples
  mayonnaise or salad dressing)

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More Types

• Gels colloid in which liquid particles are
  spread out in a solid (examples gelatin, jelly,
  stick deodorant)
• Aerosol colloid in which solid or liquid
  particles are suspended in a gas (examples fog
  or smoke)

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Mixture Separation Techniques

• Filtration part must be soluble
• Distillation must know boiling points of two
  liquids
• Recrystallization must know melting points and
  crystal structures
• Solubility must know nature of substances
• Size, magnetic/electrical attraction, density
• Chromatography must know affinity to surface
  versus affinity to solvent used

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Law of Conservation of Mass/Energy

• Finite amount of matter and energy in universe
• Matter to energy and energy to matter changes
  occur
• Energy can be changed in form (see examples in
  class) without loss to universe
• Matter can be changed in form or state without
  loss to universe

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Laws of Thermodynamics

• First law conservation of energy
• Second law entropy increases in all natural
  processes
• Third law we cannot reach absolute zero
• Zeroth law If Ta Tb and Tb Tc then Ta Tc
  (thermal equilibrium in balance)

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4 Forces in Nature

• Gravity force is dependent on mass and the
  distance between objects
• Electromagnetism affects all electrically
  charged objects
• Strong Nuclear Force binds together the
  particles of nucleus
• Weak Nuclear Force responsible for nuclear decay
  (radioactivity)

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Moles

• The number of moles of any substance is
  characterized by the coefficient
• The mass of one mole of a substance is shown in
  the formula mass
• One mole of any substance contains
• 6.02 E 23 particles
• One mole of any gas occupies 22.4 L of volume at
  standard temperature and pressure