9/21/15 ISOTOPES
MONDAY, SEPTEMBER 21 ST
ISOTOPES
9/21/15
Objective:
•  Define isotope and identify isotopes of different elements
(Learning Goal 2.3)
Do Now:
1.  Write the Atomic symbol for an atom containing:
•  3 protons, 3 neutrons
2.  Write the atomic symbol for an atom of Bromine with a mass
number of 81.
1 9/21/15 ISOTOPES
9/21/15
Do Now:
1.  Write the Atomic symbol for an atom containing:
• 
3 protons, 3 neutrons
6
3
Li
2.  Write the atomic symbol for an atom of Bromine with a mass
number of 81.
81
37
Br
ISOTOPES
•  Isotopes are atoms of the
same element with
different mass numbers
•  Isotopes of the same
element have the same
number of protons but a
different number of
neutrons
2 9/21/15 ISOTOPE NOTATION
•  We notate isotopes by writing:
•  element name-mass number
•  For Example:
Lithium-6
Lithium-7
Lithium-8
LEARNING CHECK
Isotopes have the same number
of ________________ but different
________________
3 9/21/15 LEARNING CHECK
Isotopes have the same number
of PROTONS but different
MASSES
LEARNING CHECK
In an isotope, which part of the atom is
different:
a.  Protons
b.  Neutrons
c.  Electrons
4 9/21/15 LEARNING CHECK
In an isotope, which part of the atom is
different:
a.  Protons
b. Neutrons
c.  Electrons
PRACTICE!
Fill in the table Below
Atomic
Symbol
Isotope Notation
# Protons
# Neutrons
19
18
19
20
Mass
Number
143
235
146
238
Europium-151
Europium-153
5 9/21/15 PRACTICE!
Fill in the table Below
Atomic
Symbol
Isotope Notation
# Protons
# Neutrons
Mass
Number
37
19K
Potassium-37
19
18
37
39
19K
Potassium-39
19
20
39
235
92U
Uranium-235
92
143
235
238
92U
Uranium-238
92
146
238
151
63Eu
Europium-151
63
88
151
153
63Eu
Europium-153
63
90
153
6