Atomic Structure

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Atomic Structure
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Atomic Structure

• Atoms are the smallest particle of all matter.

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Discovery of the Atom

• Democritus (300 B.C.E)
• Greek mathematician
• 1st to suggest the existence of atoms

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Discovery of the Atom

• John Dalton (1808)
• English Chemist
• Developed the Atomic Theory to support the
  existence of atoms.

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Discovery of the Atom

• Atomic Theory
• Every element is made of tiny, unique particles
  called atoms that can not be broken down.
• Atoms of the same element are exactly the same.
• Atoms of different elements can join to form
  molecules.

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Discovery of the Atom

• Ernst Ruska (1931)
• Invented the Electron Microscope which allows
  scientists to view and study atoms.
• Lise Meitner Otto Hahn (1939)
• Discovered that atoms CAN be broken apart
• Invented nuclear reactors

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FAT MAN
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Atom Bomb

• On August 9, 1945
• The U.S. dropped Fat Man on Nagasaki,
• Japan
• 75000 were killed 75,000 severely injured

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Parts of the Atom

• Atoms have three parts
• Protons positively charged particles (p)
• Neutrons uncharged particles (n)
• Electrons negatively charged particles (e-)

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Nitrogen Atom
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Nucleus vs. Orbitals

• Middle of the atom
• Protons Neutrons are found here

• Pathway of electrons as they orbit the nucleus.

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Total Charge of Atoms

• Nitrogen Atom
• 7 protons (p)
• 7 neutrons (n)
• 7 electrons (e-)
• What is the overall charge????
• HINT positive and negative charges cancel each
  other out

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Atomic Mass (Weight)

• Each proton neutron has a mass of 1
  a.m.u. (Atomic Mass Unit)
• Electrons have no mass.
• Nitrogen Atom
• 7 protons
• 7 neutrons
• 7 electrons
• What is the total mass of this atom????

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Bohr Models

• Niehls Bohr
• Discovered that electrons occupy different types
  of orbitals called energy levels. (much like the
  planets around the sun)

1st energy level 2 electrons 2nd energy level
8 electrons 3rd energy level 8 electrons
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Valence Electrons

• An electron or electrons in the outermost energy
  level of an atom.
• Lets look at the Nitrogen atom again!!
• HOW MANY Ve-

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3.2 The Periodic Table
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Organizing The Periodic Table

• Elements are given chemical symbols and arranged
  by their unique Atomic Number.
• Atomic Number Tells you the number of protons
  found in the nucleus of an atom.
• NOTE of protons of electrons

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Oxygen Atom
How many protons? _______________ How many
neutrons? ______________ How many electrons?
______________
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Oxygen Atom
8
How many protons? _______________ How many
neutrons? ______________ How many electrons?
______________
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Oxygen Atom
8
How many protons? _______________ How many
neutrons? ______________ How many electrons?
______________
8
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Oxygen Atom
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How many protons? _______________ How many
neutrons? ______________ How many electrons?
______________
8
8
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Organizing the Periodic Table

• Periodic Law elements are arranged in order of
  increasing atomic number.
• Periods horizontal rows on periodic table
• Groups vertical columns on periodic table
• SHORTCUT the group number tells you how many
  valence electrons that atom has!!!!
• Ill show you!!!

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Ionization

• When atoms gain or lose electrons they form ions
  (atoms with a charge!!)
• 1) Cations Ions with a positive () charge
• -electrons have been ___________
• 2) Anions Ions with a negative (-) charge
• -electrons have been ___________

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Ionization

• When atoms gain or lose electrons they form ions
  (atoms with a charge!!)
• 1) Cations Ions with a positive () charge
• -electrons have been ___________
• 2) Anions Ions with a negative (-) charge
• -electrons have been ___________

lost
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Ionization

• When atoms gain or lose electrons they form ions
  (atoms with a charge!!)
• 1) Cations Ions with a positive () charge
• -electrons have been ___________
• 2) Anions Ions with a negative (-) charge
• -electrons have been ___________

lost
gained
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Why do Ions form???

• RULE Atoms want to have their valence shell
  (outermost energy level) FULL.

3 protons
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Why do Ions form???

• RULE Atoms want to have their valence shell
  (outermost energy level) FULL.

3 protons
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Why do Ions form???

• RULE Atoms want to have their valence shell
  (outermost energy level) FULL.

Nowwhat is the easiest way for this atom to fill
its valence shell?
3 protons
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Why do Ions form???

• RULE Atoms want to have their valence shell
  (outermost energy level) FULL.

Nowwhat is the easiest way for this atom to fill
its valence shell?
3 protons
LOSE ONE ELECTRON
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Why do Ions form???

• RULE Atoms want to have their valence shell
  (outermost energy level) FULL.

Nowwe have a HAPPY ATOM!!!
3 protons
Li
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Isotopes

• Atoms of the same element with a different number
  of neutrons
• Mass number protons neutrons
• Mass number will change for each isotope of an
  element
• protons stays the same
• electrons stays the same

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Isotopes

• Carbon (Carbon-12)
• 6 protons, 6 neutrons, 6 electrons
• Carbon-13 (mass number 13)
• 6 protons, ___ neutrons, 6 electrons
• Carbon-14 (mass number 14)
• 6 protons, ___ neutrons, 6 electrons

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Isotopes

• Carbon (Carbon-12)
• 6 protons, 6 neutrons, 6 electrons
• Carbon-13 (mass number 13)
• 6 protons, _7_ neutrons, 6 electrons
• Carbon-14 (mass number 14)
• 6 protons, ___ neutrons, 6 electrons

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Isotopes

• Carbon (Carbon-12)
• 6 protons, 6 neutrons, 6 electrons
• Carbon-13 (mass number 13)
• 6 protons, _7_ neutrons, 6 electrons
• Carbon-14 (mass number 14)
• 6 protons, _8_ neutrons, 6 electrons

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Isotopes

• Carbon Isotopes