1. Atomic Theory, Isotopes, and Radioactive Decay
7.1
Atomic Theory, Isotopes, and Radioactive Decay

2. Today’s lesson Atomic structure Subatomic particles Atomic forces
Isotopes
Radioactive decay
Homework:
Text: Chapter 7, pages
Workbook: Chapter 7, pages

3. The Atom Fill out the diagram below using the word bank on the right
Nucleus
Electron shells
Protons
Valence shell
Neutrons
Electrons

4. Properties of Subatomic Particles
Charge
Mass (amu)
Location
A change in number results in a
Determines
Proton
Electron
Neutron

5. Stability
Stability refers to whether or not the atom will break apart into smaller pieces
Why would an atom break apart? + + + -

6. Forces in an atom Electromagnetic force Strong nuclear force
Oppositely charges attract
Like charges repel
Charged particles attract neutral particles
Force responsible for
______________________________
Strong nuclear force
Binds neutrons and protons together to form the nucleus
Responsible for
Weak nuclear force
Stabilize atoms
Can cause
____________________________
Gravitational force
Force of
______________________________
Proportional to mass so it is weak in an atom

7. What trend do you see between expected mass and periodic mass?
Atom
Number of Protons
Number of Electrons
Number of Neutrons
Expected Mass
Periodic Table Mass H He C Ne K Cu I
What trend do you see between expected mass and periodic mass?
Why are the masses on the periodic table decimal values?

8. Isotopes Elements can exist in various isotopes
Different isotopes will have the same number of protons and electrons but different numbers of neutrons
Example: Carbon
Carbon is found in three naturally occurring isotopes
______________________________________________________________ ______________________________________________________________

9. Calculating periodic table masses
The mass on a periodic table takes into account the masses of the different isotopes and their relative abundance
Stability influences abundance, unstable particles won’t exist long in the form
Example: Carbon
General formula: ________________________________________________________

10. Radioactivity
Unstable particles split apart, releasing smaller particles and energy
RADIOACTIVITY: the emission of energy or particles caused by the spontaneous disintegration of atomic nuclei
Radioactive decay: the process in which unstable nuclei lose energy by emitting radiation in the form of particles and energy

11. Three main types of radioactive decay
Alpha decay
Beta decay
Gamma decay Releases energy }
Release particles (and energy)

12. Alpha decay
The emission of an alpha particle (helium nuclei) from a nucleus
__________________________________________________________

13. Beta decay
Beta decay: when a neutron changes into a proton, which stays in the nucleus, and a high-energy electron
____________________________________________________ _

14. Gamma radiation
Gamma decay: a high-energy gamma ray given off as an isotope falls from a high-energy state to a low-energy state
_______________
________________________________________________________ _
________________________________________________________

17. Electromagnetic spectrum
The energy released from a radioactive source takes the form of waves
Depending on the amount of energy released, the waves will have various wavelengths
The different wavelengths form the electromagnetic spectrum

19. Today’s lesson Atomic structure Subatomic particles Atomic forces
Neutrons role in stability
Atomic forces
Electromagnetic
Strong nuclear
Weak nuclear
Gravitational
4. Isotopes
Definition/representing
Calculating the periodic table mass
5. Radioactive decay
Definition
Alpha
Beta
Electromagnetic spectrum
Gamma

20. Next lesson
Half-life
Carbon-dating