TOPIC: RadioactivityTOPIC: Radioactivity & Natural Transmuations Do Now: Where on your reference...
Transcript of TOPIC: RadioactivityTOPIC: Radioactivity & Natural Transmuations Do Now: Where on your reference...
TOPIC: Radioactivity & Natural Transmuations
Do Now: Where on your reference table can you find radioactive particles?
Not all isotopes are stable
Stable isotopes have…
1:1 ratio of n0 to p+ (for elements <20)
1.5:1 ratio of n0 to p+ (for elements >20)
Beyond Element 83 are very unstable (radioactive)
• No amount neutrons can hold nucleus together once it has 83+ protons
• All Elements 83 and above on PT are radioactive
• Other elements may have radioactive isotopes applet
Radioisotopes- unstable nucleus – they are radioactive
the nucleus of element emits subatomic particles and/or electromagnetic waves…by emitting these particles,nucleus changes into different element (it’s trying to become more stable)
Radioactive Decay Series
• Sometimes 1 transmutation isn’t enough to achieve stability
• Some radioisotopes go through several changes before they achieve stability (and are no longer radioactive)
U-238 PB-206
Transmutation-When an element turns into a different element. This occurs when the number of protons changes.
These subatomic particles that are emitted were discovered around 1900 • Alpha rays• Beta rays• Gamma rays
Radioactivity – Rutherford again!
Penetration & Shielding
2 Neutrons & 2 Protons
Charge = +2Mass = 4amu
42He
Beta Particle – fast moving electronBeta Particle – fast moving electron
Transmutation
• 2 types–Natural–Artificial
Natural Transmutation
Happens all by itself (spontaneous)Happens all by itself (spontaneous)
Not affected by Not affected by anythinganything in environment in environment
• 1 term on reactant side• Original isotope
• 2 terms on product side• Emitted Particle • New Isotope
Natural Transmutation
16N 0e + 16O7 -1 8
1 term on reactant side
2 terms on product side
Balancing Nuclear Equations
16N 0e + 16O7 -1 8
Conservation of mass number: 16 = 0 + 16
Conservation of atomic number: 7 = -1 + 8
232Th 4He + X9090 22
Conservation of Mass Number:Conservation of Mass Number:
sum of mass numbers on left side must = sum of mass numbers on left side must = sum of mass numbers on right sidesum of mass numbers on right side
YY
Z
232 = 4 + Y so Y = 228
232Th 4He + 228X9090 22
Conservation of Atomic Number:Conservation of Atomic Number:
sum of atomic numbers on left side must = sum of atomic numbers on left side must = sum of atomic numbers on right sidesum of atomic numbers on right side
ZZ
90 = 2 + Z so Z = 88