Transcript The Atom

The Atom
From 400 BC to now
The Atom

Who are some famous people that helped
develop the theory of the atom?
Democritus
 Dalton
 Thomson
 Rutherford
 Bohr
 Schrodinger/Hiesenberg
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The Atom
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What did Millikan do?
Millikan found the charge of an electron.
 It is 1.602 x 10-19 Coulombs.
 He then found that the mass was 1/1840 x
that of a proton.
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The Atom
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What are the parts of an atom?
Proton, +, nucleus
 Electron, -, electron cloud
 Neutron, 0, nucleus
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The Atom
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What are isotopes?
Isotopes contain different numbers of
neutrons, but have equal protons.
 Equal protons makes them the same element.
 Neutron differences give them different
properties.
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The Atom
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How do we find Isotope abundances?
Abundances are found by using % of each
isotope involved.
 Example: Boron has 80.2% boron-11, and
19.8% boron-10. What is the atomic mass?
 10.8 AMU
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The Atom
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What happens to unstable nuclei?
Unstable nuclei decay.
 Alpha radiation.
 Beta radiation.
 Gamma radiation.
 We will talk about others later.
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The Atom
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What do we know about electrons?
They surround the nucleus.
 They are free to move from atom to atom.
 They determine the characteristics of an atom
 They form bonds.
 They determine the ions formed.
 They fill orbitals.
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The Atom
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Who are some people associated with
electrons in atoms?
Planck
 Bohr
 de Broglie
 Heisenberg
 Schrodinger
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Energy levels

What are they?
1, 2, 3, 4, 5 . . .
 Each one represents another “shell” on an
atom
 Each one has an increasing number of
sublevels
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Sublevels
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What are they?
S, P, D and F
 What does each one hold?

S
orbital: 2 electrons of opposite spin (1 orbital)
 3 P orbitals: 6 electrons of 3 clockwise 3
counterclockwise spin (3 orbitals)
 5 D orbitals: 10 electrons of 5 clockwise and 5
counterclockwise spin (5 orbitals)
 7 F orbitals: 14 electrons of 7 clockwise and 7
counterclockwise spin (7 orbitals)
S P D and F orbitals
Examples
What is the outer orbital in Helium?
 What orbital is filling in Nitrogen?
 What orbital is the outside of Copper?
 What is the outside of Europium?

Drawing orbital filling
Draw Aresenic.
 How do we use the shortcut?
 You can skip up to the Nobel Gas right
before your element.
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Pauli exclusion principle
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What does it say?
An atomic orbital may only hold 2 electrons at
one time.
 Each electron has to have a different spin
(clockwise or counterclockwise).
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Electron orbital filling
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What determines their order?
The aufbau principle states that electrons
occupy the orbitals of lowest energy first.
 How do we find this order?
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Spin rules
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What determines the spin of the electron?

Hund’s rule.
 This
rule states that electrons fill the orbitals in a
way that gives the atom the largest number of
electrons with the same spin.
What does this mean?
Stability

What adds to the stability of the atom?

Not all atoms follow the aufbau principle.
 Cr
and Cu