Download Pre-AP Chemistry

Pre-AP Chemistry
Name _______________________________
Period: ______________
2 • Atomic & Molecular Structure
Atomic Theory Notes #1
Relevant textbook pages: 65 - 85
Section Objectives
 Students know protons and neutrons in the nucleus are held together by nuclear forces
that overcome the electromagnetic repulsion between the protons. (11a)
 Students know the nucleus of the atom is much smaller than the atom yet contains most of
its mass. (1e)
 Students recognize the usefulness and limitations of models and theories as scientific
representations of reality. (I&E 1g)
 Students recognize the cumulative nature of scientific evidence. (I&E 1k)
Dalton’s Theory
A Summary of Dalton’s Atomic Theory:
1. An element is composed of tiny, _____________, _____________ particles called _______.
2. All atoms of an element are _____________and have the same _____________.
3. Atoms of different _____________combine to form _____________.
4. Compounds contain atoms in small _____________number ratios. Atoms can combine in
more than one _____________to form different _____________.
Good stuff:
Part 3: Chemical reactions occur when atoms are joined, _____________or _____________
Part 4: _____________combine in whole number ratios
Not so good stuff:
Part 1: Atoms _____________be separated: _____________particles
Part 2: All atoms _____________identical: _____________
Thomson Model of the Atom
Thomson Atomic Theory (1903)
Post discovery of the _____________
Also known as: the _____________Pudding model
Good stuff: accounts for both _____________and _____________
Not so good stuff: Nothing about the _____________or the _____________of p+, e-, or no
Rutherford Model of the Atom
Ernest Rutherford
Post discovery of the _____________
A.K.A. _____________atomic model
1
Proposed two things:
Nuclear atom, with e- surrounding the _____________center
_____________nucleus, with rest of atom mostly _____________space
Problem: No _____________as to why _____________do not collapse onto the
_____________.
Now we know: The nucleus is held together by the _________________________________
Rutherford’s Gold Foil Experiment
Rutherford fired _____________particles at thin gold _____________. If the “plum pudding”
model of the atom was correct, most alpha particles should _____________.
However, _____________of the alpha particles were _____________backwards.
Rutherford’s Gold Foil Experiment
Rutherford’s Findings

The nucleus is small, dense & _____________charged

Atom is mostly __________________________

The nucleus made of __________________________

The _____________ around the nucleus

Called the “_______________________________________”
Subatomic Particles
2
PAP Chemistry
Name _______________________________
Period: ______________
2 • Atomic & Molecular Structure
Atomic Structure Notes #2
Section Objectives
 Students know how to relate the position of an element in the periodic table to its atomic number and
atomic mass. (1a)
 Students know the nucleus of the atom is much smaller than the atom yet contains most of its mass. (1e)
 Students know some naturally occurring isotopes of elements are radioactive, as are isotopes formed in
nuclear reactions. (11c)
Atomic Number
Atoms are composed of __________________, ___________________, and __________________
Elements are different because they contain different numbers of ________________________
The “atomic number” of an element is the number of ________________________in the nucleus
# protons in an atom = # ________________________
Give the number of protons and electrons for:
Carbon
Phosphorus
Gold
Mass Number
Mass number is the number of protons and neutrons in the nucleus of an atom:
Complete Symbols
Contain the symbol of the element, the mass number and the atomic number.
Neutrons
Give the number of neutrons for:
Carbon
Phosphorus
Uranium
Hydrogen
3
Symbols
Find each of these:
a) number of protons
b) number of neutrons
c) number of electrons
80
35
Br
d) Atomic number
e) Mass Number
If an element has an atomic number of 34 and a mass number of 78, what is the:
a) number of protons
b) number of neutrons
c) number of electrons
d) complete symbol
4
If an element has 91 protons and 140 neutrons what is the
a) Atomic number
b) Mass number
c) number of electrons
d) complete symbol
If an element has 78 electrons and 117 neutrons what is the
f) Atomic number
g) Mass number
h) number of protons
i)
complete symbol
Isotopes
Dalton was wrong about all atoms of the same element being __________________
Atoms of the same element can have different numbers of __________________.
Thus, different __________________numbers.
These are called __________________.
Naming Isotopes
We can also put the mass number after the name of the element:
carbon-13
carbon-14
uranium-235
2H
15N