Atomic Structure

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Atomic Structure

• What are atoms? Daltons Theory
• A. Every element is made of tiny, unique
  particles called
  atoms that cannot be subdivided
• B. Atoms of the same element are exactly
  alike.
• C. Atoms of different elements can join to
  form molecules.

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• II. Whats in an atom?

A. nucleus the center of an atom, made up of
protons and neutrons
B. proton positively charged sub-atomic partic
le
C. neutron a neutral sub-atomic particle (no
charge)
D. electron very tiny negatively charged
sub-atomic particle, found outside the nucleus
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• E. Atoms have no overall charge
• 1. An un-reacted, elemental atom has the same
  number of protons as electrons
• 2. Each proton has 1 positive charge and each
  electron has 1 negative charge.
• 3. Positive charges and negative charges cancel
  each other out.

2 protons 2 charges 2
neutrons 0 charge 2 electrons
- 2 charges
0 charge
7 protons 7 charges 7
neutrons 0 charge 7 electrons
- 7 charges
0 charge
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III. Models of the Atom

• Bohrs Model
• 1. Envisioned the atom as a small replica of
  the solar system, with the electrons orbiting
  the nucleus in set patterns

B. Modern Theory 1. Electrons move randomly
around the nucleus in particular areas, known as
clouds or orbitals
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• 2. Every atom has valence electrons
• a. Electrons are arranged in energy levels.

i. Each energy level can hold only a specific
number of electrons ii. Electrons start at the
energy level closest to the nucleus and fill up
one energy level after another.
b. valence electron an electron
in the outermost energy level of an atom