This document provides information about isotopes, including: 1. Isotopes of an element differ in the number of neutrons but have the same number of protons and electrons, making their chemical behaviors similar. 2. Specific isotopes are represented by nuclear symbols noting the element symbol, mass number superscript left of the symbol, and atomic number subscript left of the symbol. 3. The atomic mass of an element depends on the relative abundance of its isotopes, calculated by multiplying each isotope's mass by its natural percentage and totaling.

1. isotopes

2. LEARNING
OBJECTIVES
1 2 3

3. isotope
•atoms of a given
element that differ in
the number of neutrons

4. How are isotopes of an element similar?
How are they different?
similar
(this is because they have
the same numbers of
protons and electrons and
subatomic particles are
responsible for chemical
behavior)
(different mass and
different number of
neutrons)
different

5. How do we represent specific isotopes?
• the symbol of
the element
is written
first
1
• the mass number
is written as a
superscript to
the left of the
symbol
• the atomic
number is
written as a
subscript to the
left.
2 3
• Nuclear symbols are used to represent
specific isotopes
• To write a nuclear symbol:

7. LEARNING CHECK
•Given a nuclear symbol, what does
the top left number represent?
•What does the bottom left number
represent?

8. Can we write isotopes in a different way?
• We can also use the mass number and the name of
the element to designate the atom or isotope
– This is called hyphen notation
•For example, two isotopes of carbon are carbon-12 and
carbon-14
–The nuclear symbols for these two isotopes would be:

9. LEARNING CHECK
•What does the
number after the
hyphen represent?

10. LEARNING CHECK
• Boron consists of two isotopes, B-10 and B-11
1.) Determine the number of neutrons in each of the
isotopes
2.) Using the periodic table, write the nuclear symbol
for each isotope given in hyphen notation
a.) B-10:
b.) B-11:
10 11
5 5
B B
5 neutrons
6 neutrons

11. What does the atomic mass of an element depend on?
• The atomic mass of an element depends on the
abundance of its isotopes.
 If you know the mass of the isotopes and the percent
(fractional) abundance of the isotopes, you can
calculate the element's atomic mass.

12. How do I calculate the atomic mass of an element based on
percent natural abundance and isotopic masses?
• Example: Chlorine has 2 naturally occurring isotopes
• To calculate the average atomic mass:
–add the mass of each isotope multiplied by its percent abundance
• This is the solution for chlorine:
(34.968852) * (0.7577) + (36.965303) * (0.2423) = 35.45 amu
Mass # Mass Percent Abundance
35 34.968852 75.77
37 36.965303 24.23

13. EXAMPLE

15. What is the use of Protium?
• Protium contains pantoprazole which
is the active ingredient.
• Protium is a selective “proton pump
inhibitor,” a medication that reduces
the amount of stomach acid
produced. It is used to treat stomach
and intestine acid-related illnesses
uses

16. • Deuterium and its compounds are
used as a non-radioactive label in
chemical experiments and in solvents
for 1H-NMR spectroscopy. Heavy
water is used as a neutron moderator
and coolant for nuclear reactors.
• Deuterium is also a potential fuel for
commercial nuclear fusion
uses

17. • Tritium gas is combined with
phosphor to create luminescence.
The light source does not require
electricity or electrical wiring, making
it ideal for exit signs, emergency
lighting in commercial buildings and
airplanes and for airport runway
lights.
• Tritium is also used as a tracer in
uses

18. evaluation

19. Nuclear
Symbol
Complete based on the
following information:
29 protons, mass 65
Barium - 138
17 protons, mass 36
Tin - 120
16 protons, mass 30
Learning Check

21. ASSIGNMENT

22. let's work together
(by pair)