Nuclear Chemistry

The Atom The atom consists of two parts: 1. The nucleus which contains: 2. Orbiting electrons. protons neutrons

X A Z Mass number Atomic number Element symbol = number of protons + number of neutrons = number of protons

U U There are many types of uranium: Mass # Atomic # Number of protons Number of neutrons Mass # Atomic # Number of protons Number of neutrons

Same number of protons but different number of neutrons is an….. ISOTOPE

Most naturally occurring isotopes are stable.

Atoms want to be stable

Determined by ratio of p + to n 0 Nucleus Stability

Radioactive Decay (radioactivity) Unstable nuclei decomposes into stable nuclei Half- Life is the time it takes for this decay to occur.

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Half Life: Time for half of the radioactive nuclide to decay 1.How much of a 100. g sample of 198 Au is left over 8.10 days if its half-life is 2.70 days?

2. A 50.0 g sample of 16 N decays to 12.5 g in 14.4 seconds. What is the half-life?

3. The half life of 42 K is 12.4 hours. How much of a 750g sample is left over after 62.0 hours?

4. What is the half-life of 99 Tc if a 500 g sample decays to 62.5g in 639, 000 years?

5. There are 5.0 g of Iodine -131 left after days. How many grams were in the original sample if its half-life is 8.07 days?

an alpha particle (  ), a beta particle (  ), or a gamma ray  Radioactive Decay emits:

When an unstable atom creates an alpha particle. Alpha particle is identical to that of a helium nucleus. It contains two protons and two neutrons. Alpha Decay He 4 2

Alpha Decay Ra Rn He 4 2

X A Z Y A - 4 Z He 4 2 Alpha Decay unstable atom more stable atom alpha particle

Alpha Decay Ra He 4 2 Th U Th He Pb He 4 2 Po

Beta Decay Beta particle is a fast moving electron created when a n 0 changes into a p + & e - When an unstable atom creates a beta particle.

Beta Decay Po  0 At

X A Z Y A Z  0 Beta Decay unstable atom more stable atom beta particle

Beta Decay Bi Po  0 -1 Pb Tl  0 Pa Th  0

Gamma Decay Not a charged particle it is energy, it’s a photon. Electromagnetic radiation with high frequency

Draw the correct wave

Symbol CompositionRangeShield Alpha Particle He or α Helium nucleus Beta Particle Gamma Ray short Paper, skin

Symbol CompositionRangeShield Alpha Particle He or α Helium nucleus Beta Particle e - or β Electron Gamma Ray short Paper, skin Heavy Clothing, glass, light metals, plastic

Symbol CompositionRangeShield Alpha Particle He or α Helium nucleus Beta Particle e - or β Electron Gamma Ray  Photons (electromagnetic spectrum) short Paper, skin Heavy Clothing, glass, light metals, plastic Long Lead or concrete