- Composition Notebook
Isotopes are atoms of the same element
that have a different number of neutrons
in their nuclei.
Protons make the
element what it is !
• Isotopes of an element will have the
same number of protons but a
different number of neutrons.
• The number of protons in the
nucleus of an atom and is the same
for all atoms of the same element.
Mass Number
•is the number of protons +
the number of neutrons in
the nucleus of an atom
and will be different for
each isotope of an
element.
Isotope classification
• Isotopes can be classified as
natural (found in nature) or
man made (artificial or
synthetic).
• Isotopes can also be classified
as stable or unstable
Stable vs. Unstable
• A stable isotope does NOT
undergo radioactive (or nuclear)
decay.
• An unstable isotope undergoes
radioactive (or nuclear) decay.
Unstable isotopes are also known
as radioisotopes or radionucleides
Examples of Isotopes- atoms with
different numbers of neutronsnaturally occurring isotopes
•
•
•
•
•
•
•
•
Hydrogen- 1 and Hydrogen -2
Helium-3 and Helium-4 (one extra neutron)
Lithium-3 and Lithium-7 (4 extra neutrons)
Boron-10 and Boron-11 (one extra neutron)
Carbon-12, Carbon-13, Carbon-14
Nitrogen-14 and Nitrogen-15
Oxygen-16, Oxygen-17, and Oxygen-18
Neon- 20, Neon-21, and Neon-22
How are the carbon atoms different?
Unstable Isotopes
• Carbon-14 (two more neutrons than C-12)
• Uranium-234, Uranium-235, Uranium-238
Practice Drawing Isotopes
Helium-3 and Helium-4 (one extra neutron)
Lithium-3 and Lithium-7 (4 extra n
Practice Drawing Isotopes
Lithium-3 and Lithium-7 (4 extra neutrons)
Boron-10 and Boron-11 (one extra neutron)
Carbon-12, Carbon-13, Carbon-14
Radioactivity
• A nucleus of an atom is unstable and
releases subatomic particles.
• Radioactivity is a random process,
meaning that it is physically impossible to
predict whether or not a given atomic
nucleus will decay and emit radiation at
any given moment
United Streaming
Resources
Radioactivity: Nuclear
Disintegration and
subatomic particles
Radium and Radioactivity 2
min clip
Welcome to
Discovery Education
Player
Follow Up Questions
• What is an isotope?
• What subatomic particle
makes an atom an isotope?
• Do isotopes have different
numbers of protons?
Follow Up Questions
• What is radioactivity?
• Where does radioactivity happen in
the atom?
• What is released when an atom
decays?
• What happens to the atom when it
decays? Does it change?