Transcript Atomic Structure

Atomic Structure
Section 3.1, p.70-76
Hydrogen
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Atomic number: 1
Name: Hydrogen
Symbol: H
Family: Nonmetals
• Commonly combines with itself to form a
diatomic molecule, H2
Democritus’ Model of the Atom
• 4th Century B.C. to 1808
• “The universe is made of invisible units called
atoms.”
• “The movements of atoms cause changes in
matter”
Helium
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Atomic number: 2
Name: Helium
Symbol: He
Family: Noble gases
• Recovered from oil drilling operations where
radioactive alpha particles combine with free
electrons to form the element.
Dalton’s model of the Atom
• 1808 to 1913
• “Every element is made of
tiny, unique particles called
atoms that cannot be
subdivided.”
• “Atoms of the same element
are exactly alike.”
• “Atoms of different elements
can join to form molecules.”
Lithium
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Atomic number: 3
Name: Lithium
Symbol: Li
Family: Alkali Metals
• Used in the aerospace industry as a compound
that absorbs poisonous carbon dioxide from
manned space capsules (LiOH)
Bohr’s Model of the Atom
• 1913 to 1925
• “Electrons move in set paths
around the nucleus much like
the planets orbit the sun in our
solar system.”
• “Each electron has a certain
energy determined by its path,
which is its energy level.”
• “Electrons can only have certain
energy levels.”
Beryllium
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Atomic number: 4
Name: Beryllium
Symbol: Be
Family: Alkaline Earth Metals
• Found in nature as part of a compound in
precious and semi-precious stones such as
aquamarine and emerald
Modern Theory of the Atom
• 1925 to present
• “Electrons behave more like waves on a
vibrating string than they do like particles.”
• “Electrons are found in ORBITALS within
energy levels.”
Valence Electron (outermost energy level)
neutrons
Electron
Cloud
protons
Boron
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Atomic number: 5
Name: Boron
Symbol: B
Family: Nonmetal Semiconductor
• A component of the compound Borax, which is an
ingredient in detergent and cosmetics. In some
countries, it is used as a food additive similar to salt,
but is banned for this purpose in the U.S. Some foods
containing it include French and Iranian caviar.