Chapter 10.1b

*What happens during alpha decay?

*Nucleus emits 2 neutrons and 2 protons

*Symbolized as:

=42He

*Starting (reactant) Isotope is known as “mother”

*Ending (product) Isotope is known as “daughter”

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)

Alpha Decay

Alpha particle

*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:

1 Neutron 1 Proton + 1 Electron (ejected)*Change from “mother” isotope (reactant) to “daughter” isotope (product):

*Lost 1 neutron & Gained 1 proton

*Mass numbers are same

*emitted beta particle (electron) has insignificant mass

Nuclear equation for beta decay of thorium-234

(write down following equation)

Beta Decay

Beta particle

• 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:

*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 ) as it decays.

(write down following equation)

Gamma Decay

Gamma Ray

•Atomic Mass: 210 = ? + 4

(210 – 4 = 206)•Atomic Number: 84 = ? + 2

(84 – 2 = 82)

•Element with atomic number of 82 is lead (Pb)

1. Write a balanced nuclear equation for the alpha decay of thorium-232.

You Try!

1. Write a balanced nuclear equation for the alpha decay of thorium-232.

•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

You Try!