Chapter%204%20Atoms%20and%20the%20Periodic%20Table

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Chapter 4Atoms and the Periodic Table

• Section 1
• Atomic Structure
• p. 104

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Objectives

• Analyze development of Atomic Theory
• Describe the subatomic particles and their
  behaviors

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• Atomic Theory
• sesdfAtomic Theory Rap

A. Democritus (300 BC- Greek) 1. Said
universe was made of invisible
units called atoms 2. Atom means unable to
be divided
B. John Dalton (school teacher 1808) 1.
Agreed with Democritus but had evidence to
support ideas (Atoms cant be divided) 2.
All atoms of an element are alike 3. Atoms
join to form compounds
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II. What is an atom?
A. Nucleus
1. Proton a. Positive charge b. Mass 1 x
10-27 kg
2. Neutron a. Neutral (no) charge b. Mass
1 x 10-27 kg
B. Electron Cloud 1. If the nucleus was a marble
the atom would be the size of a
stadium 2. Electrons travel at near the speed of
light 3. Negative charge with a mass of
9.11 x 10-31 kg C. Unreacted atoms have no
charge
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III. Modern Models of the Atom
A. Neils Bohr (1913- Denmark) 1. Electrons
act like the planets in a solar
system 2. Energy is determined by its
path around the nucleus- must gain
energy to move to a higher level
B. 1925 Bohrs model no longer worked 1.
Electrons act more like waves 2. Wave-Particle
Duality of Nature (can act as
both)
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C. Quantum Theory (Model) 1. Electrons exact
location cannot be known Heisenbergs
Uncertainty Principle (You cant observe
something without changing it) 2. Electrons can
exist in energy levels- 1st 2 Electrons,
2nd 8, 3rd 18, 4th 32
3. Electrons are found in orbitals in the energy
levels- defined by shape (p. 109) a. S
orbital can have only 1 with a total
of 2 electrons b. P orbital can have 3
suborbitals with a total of 6
electrons
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c. D orbital can have 5 suborbitals with a
total of 10 electrons d. F orbital can have 7
suborbitals with a total of 14 electrons
4. Valence electrons a. Electrons in the outer
most energy level (shell) b. It
determines chemical properties and
ability to bond c. Has the magic number of 8
(stability)
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