Atomic Structure
Name _______________________________
Period ___________ Date _____________
Chapter 3 Part I Notes
3-1 Early Models of the Atom
1.
450 B.C. – Democritus: matter is composed of tiny indivisible particles
called
called _____________.
Definition of atom: Smallest part of an _________________ that retains the
______________ properties of that element.
2.
A.D. 1780 – Lavoisier: Law of Conservation of Matter states that matter is
neither __________________or ___________________. Lavoisier is
known as the ________________ of Chemistry.
3.
A.D. 1799 – Proust: Law of Definite Proportions (Constant Composition)
states that
compounds always have the ____________ elements in the same
_________________________ by _______________.
4.
A.D. 1803 – Dalton: Atomic Theory of Matter:
a.
All elements are made of _____________.
b.
All atoms in an element are ____________________.
c.
Atoms are not __________________ or _________________ in
chemical reactions.
d.
Compounds have definite ____________________of elements.
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3-2 Atomic Structure
1. 1790 - Ben Franklin: first to suggest the structure of the atom was related to______________.
He found that there were 2 types of _______________and that:
negative and negative: ___________
negative and positive:____________
positive and positive:____________
2. Cathode Ray Tube: An evacuated glass tube where a ____________ of ____________ flows
from the ___________ (negative electrode) to the _____________ (positive electrode).
3.
1897 – J.J. Thomson: a cathode ray is made of ________________, they
have _________ and are _________________ charged particles.
4.
1896 – Henri Becquerel: “discovered” _________________ using
pitchblende, a _______________ore (a ________ that has a metal in it.)
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5. Radioactivity is the _________________ emission of _______________ &_____________
from a sample. It _________________ the film in Becquerel’s drawer and left an image.
6. 1903 – Marie & Pierre Curie: Shared the __________ Prize in Chemistry with Becquerel.
They discovered 2 new radioactive elements, _______________ and ________________.
7.
1903 – Ernest Rutherford: found 3 types of ____________ radiation or
radioactive _________.
a.) α -
b.) β -
c.) γ-
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8. 1909 – Ernest Rutherford: Alpha Scattering or Gold Foil Experiment discovered a small,
central _____________ nucleus, and that most of the atom is ____________ ___________.
3-2
Models of the Atom
1. 1897 – J.J. Thomson: Thought the atom looked like “__________ _____________” with
negative charges distributed throughout:
2. 1909 – Rutherford: Small dense ______________ nucleus (protons) with electrons outside.
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3.
1913 – Neils Bohr: thought the atom was like the _______________
______________ (planetary model). This was inaccurate and too simplistic:
4. 1924 to present – Wave (Electron Cloud) Model: using _______________ ________________.
The electron can be found in a probability ____________:
5. There are three subatomic particles: _______________, ______________, and ______________.
Subatomic Particle
Proton
Mass (amu)
Location
Charge
( p+ )
Neutron ( n0 )
Electron ( e- )
6.
1914 - John Moseley: each atom has a different number of ________________
(atomic number). Each atom is electrically _______________ and therefore
has an equal number of ________________.
7. Mass Number: equal to the total number of _______________+_______________ in the nucleus of
an atom.
8. Ions: Formed when an atom _____________ or ___________ electrons.
a. Charge =
Ex) Mg +2 = _______ 2 electrons
# of protons:
_______
# of electrons: _______
Charge:
_______
Charge:
_______
Ex) N-3 = _________ 3 electrons
# of protons:
_______
# of electrons: _______
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9. Isotope: Atoms that have same number of ___________________, but a different number of
_________________ ( _____________.)
10. Isotopic Notation: Shorthand way of representing an ________________ of an element.
Ex)
may also be written: _____________________ or __________
Ex) Isotopes of Hydrogen:
a. hydrogen
(hydrogen - ___ )
b.deuterium
(hydrogen - ___ )
c.tritium
(hydrogen - ___ )
Isotope
Protons
Neutrons
Mass Number
Electrons
Isotopic Notation
Carbon-12
Carbon-13
Carbon-14
11. Atomic Mass: the mass of an atom expressed in _________ (atomic mass unit.) One amu is equal
to ________ the mass of a ______________________ atom.
12. Average Atomic Mass: The ____________________ average of all an element’s isotopes.
This is the number shown in the box on the ___________________ _______________.
It is calculated by
Ex) Straight Class Grade
Weighted Class Grade
Ex) carbon
Ex) hydrogen
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