Download Section Objectives

Chemistry
Name _______________________________
Period: ______________
2 • Atomic & Molecular Structure
Atomic Structure Notes #2
Relevant textbook pages: 113 - 120
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
Uranium
Phosphorus
Hydrogen
Symbols
Find each of these:
a) number of protons
b) number of neutrons
c) number of electrons
S. Cool, 2009
80
35
Br
d) Atomic number
e) Mass Number
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If an element has an atomic number of 34 and a mass number of 78, what is the:
a) number of protons
c) number of electrons
b) number of neutrons
d) complete symbol
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
S. Cool, 2009
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