Transcript 4.1 Atomic Structure

4.1 Atomic
Structure
I CAN:
-RECALL AND DISCUSS THE EFFECT OF TECHNOLOGY ON THE CREATION
OF ATOMIC MODELS AND DISCUSS HOW TECHNOLOGY INFLUENCED
THE DEVELOPMENT OF PREVIOUS AND CURRENT ATOMIC MODELS (I.E.
RUTHERFORD’S GOLD FOIL EXPERIMENT).
-CAN RECOGNIZE THAT ASSOCIATION WITH GROUP OR FAMILY IS
BASED ON SIMILAR CHEMICAL OR PHYSICAL PROPERTIES
DO
NOT TRUST
ATOMS! THEY
MAKE UP
EVERYTHING!
What are atoms?

Tiny units that determine the
properties of matter.

Properties of aluminum…

Greek philosopher Democritus

“unable to divide”

No one believed him.
John Dalton developed atomic
theory.

1808, the foundation was laid.

Still said atoms can not be divided. Is this true?

100 years later: Protons, neutrons, and electrons discovered

Atoms of given elements were exactly alike.

Atoms of different elements can join to make compounds
Atoms of building blocks of
molecules

Atom is the smallest part of an
element that still has the element’s
properties.

Atoms join together to make
molecules.

For us to see it, large numbers of
molecules must join.

Still made of 2 H and 1 O.
Atoms are made of protons,
neutrons, and electrons.

Nucleus: atom’s center which is
made up of protons and neutrons.

Proton: subatomic particle that
has positive charge

Neutron: subatomic particle that
has no charge (neutral)

Electron: subatomic particle that
has a negative charge.

Number of protons and electrons
in an atom are unique for each
element.

Ex: He has be one more proton
and electron than H.
Unreacted atoms have no overall
charge.

Atoms do not have a charge

Equal number of protons and electrons (charges cancel)
Models of an Atom

NIELS BOHR: Electrons in atom
move in set paths around nucleus
much like planets in orbit. FALSE!


Energy levels: still thought to be
true.
Modern Model: electrons behave
like waves on a vibrating string.
An electron’s exact location
cannot be determined (think fan
blades)
Electrons exist in energy levels
(shells)

The number of filled energy levels depends on the number of
electrons.

2-8-8 rule
Electrons are found in orbitals within
energy levels.

Orbital: region in an atom where there is a high probability of finding
electrons.

Probability of density

Sublevels or sub”shells”:
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S=2 (one pair)

P=6 (three pairs)
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D=10 (five pairs)
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F=14 (7 pairs)
Review

Compare to hotel…
Every atom has between one and
eight valence electrons.

Valence electron: an electron that is found in the outermost shell of
an atom that determines the atom’s chemical properties.

Lewis dot diagram.

Can be figured by electron configurations.

Vertical group indicate how many valance electrons
Rutherford's gold foil experiment

https://www.youtube.com/watch?v=zUtIrO3fUgg