*
Chapter 10.1b
*
*What happens during alpha decay?
*Nucleus emits 2 neutrons and 2 protons
*Symbolized as:
a
4
=
2
He
Alpha Decay
*Starting (reactant) Isotope is known as “mother”
*Ending (product) Isotope is known as “daughter”
Alpha
particle
Ex: Nuclear equation for alpha decay of uranium-238:
(write down following equation)
•Mass number on left = sum of mass numbers on the right
238 = 234 + 4 (Subtract 4 from the Mother to find Daughter)
•Atomic number on left = sum of atomic numbers on the right
92 = 90 + 2
(Subtract 2 from the Mother to find Daughter)
*
*What happens during beta decay?
*A neutron within the nucleus decomposes
and splits into a proton and an electron
*The electron is then emitted leaving the proton
behind.
*Symbolized as:
b=
Beta Decay
1 Neutron  1 Proton + 1 Electron (ejected)
*Change from “mother” isotope (reactant) to “daughter”
isotope (product):
*Lost 1 neutron & Gained 1 proton
Beta particle
*Mass numbers are same
*emitted beta particle (electron) has insignificant mass
Nuclear equation for beta decay of thorium-234
(write down following equation)
• Add 1 to the atomic number of the mother to find the daughter
*
*What happens during gamma decay?
*Nucleus becomes excited
*As it returns to a lower energy state it emits
energy as a photon (gamma ray)
*Light we cannot see
*Symbolized as:
g
Gamma Decay
*Atomic # and mass # stay same.
*Energy in nucleus decreases.
*Often happens during alpha or beta decay.
*Example: Thorium-234 emits both beta particles
and gamma rays (abbreviated as g) as it decays.
(write down following equation)
Gamma Ray
*Balancing Equations - Alpha
Decay of Po-210
•Atomic Mass: 210 = ? + 4
(210 – 4 = 206)
•Atomic Number: 84 = ? + 2
(84 – 2 = 82)
•Element with atomic number of 82 is lead (Pb)
You Try!
1. Write a balanced nuclear equation for the alpha
decay of thorium-232.
You Try!
1. Write a balanced nuclear equation for the
decay of thorium-232.
alpha
•Atomic Mass: 232= ? + 4
(232 – 4 = 228)
•Atomic Number: 90 = ? + 2
(90 – 2 = 88)
•Element with atomic number of 88 is radium
You Try!
2. Write a balanced nuclear equation for the beta
decay of carbon-14.
You Try!
2. Write a balanced nuclear equation for the beta
decay of carbon-14.
•Atomic Mass: 14 = ? + 0
(14 – 0 = 14)
•Atomic Number: 6 = ? – 1
(6 = 7 – 1)
•Element with atomic number of 7 is nitrogen
You Try!
3. Determine the “daughter” (product isotope)
of americium-241 alpha decay.
Alpha
Particle
You Try!
3. Determine the “daughter” (product isotope)
of americium-241 alpha decay.
•Atomic Mass: 241 = ? + 4
(241 – 4 = 237)
•Atomic Number: 95 = ? + 2
(95 – 2 = 93)
•Element with atomic number of 93 is neptunium
You Try!
4. Determine the “daughter” (product isotope)
of strontium-90 beta decay.
Beta
Particle
You Try!
4. Determine the “daughter” (product isotope)
of strontium-90 beta decay.
•Atomic Mass: 90 = ? + 0
(90 – 0 = 90)
•Atomic Number: 38 = ? + -1
(38 = 39 – 1)
•Element with atomic number of 39 is yttrium