Topic 2: Nuclear Chemistry Flashcards
How is the stability of an isotope determined?
-Stability depends on the ratio of protons to neutrons in nucleus. Stable= 1:1
-Unstable nuclei usually have more neutrons than protons
What does it mean if a nucleus is unstable? What results in an unstable nucleus ?
-Unstable nuclei usually have more neutrons than protons
-will spontaneously decay, emitting radiaton
-reason for being susceptible to radioactive decay is that the irregular ratio of P to N is not as effective at holding nucleus together
Rate of decay
know as HALF LIFE
-each isotope has a specific half life
-constant, can never be changed
-measures the time for 1/2 of the isotope to decay
-the half life will never decay to 0
Elements are radioactive if their atomic number is higher than what?
All elements with an atomic number (protons) higher than 83 are radioactive
Where/how does transmutation occur and what results?
- occurs in the nucleus
- naturally or artificially
-artificial transmutation involves bombarding nucleus by high energy particles
-spontaneous (natural) can involve release of particles from nucleus - RESULTS: atom turns into a different type of atom, therefore becoming a different element
What’s the cause and effect of nuclear fission?
Cause (can be):”shooting” nucleus with a neutron
Effect: nucleus is split
-products are not radioactive wastes
-large atom splits into 2 or more smaller
-energy is a product
What is nuclear fusion?
Combining two light (in mass) nuclei to form a heavier nuclei
-this is what powers the sun
-products are not radioactive wastes
-energy is a product
How does the energy from nuclear reactions differ from the energy from chemical reactions?
- energy released from nuclear reactions is much greater than released from chemical reactions
- energy from nuclear reactions comes from the very small fraction of mass that is lost…the reaction converts matter into energy
How can radioactive isotopes be used?
- In medicine (tracing chemical and biological processes)
- radioactive dating
- industrial measurement
- nuclear power
- detection, treatment of disease
Mass defect
-occurs in fusion AND fission
-When reactants altogether weight more than the products altogether because energy is released (mass was converted to energy)
-Calculated with E=mc^2
Forms of spontaneous transmutation (aka natural decay)
Alpha and beta decay
-only have 1 reactant
Reactants of an artificial transmutation/decay
-2 reactants
What is ionizing power? Which types of radiation have the highest and lowest?
Radiation’s ability to damage other molecules and DNA
LOWEST: gamma
HIGHEST: alpha
What is penetrating power? Which types of radiation have the highest and lowest?
-Radiation’s ability to pass through barriers
-DETERMINES ionizing power
LOWEST: alpha
HIGHEST: gamma
What does a fusion reaction look like?
- 2 reactants and 2 products
R:
1 smaller element
1 smaller element
P:
1 larger element
Energy
What does a fission reaction look like?
-2 reactants and 4 products
R:
1 neutron
1 larger element
P:
1 smaller element
1 smaller element
3 more neutrons
Energy
What are the results of gamma radiation?
Mass and atomic number STAY THE SAME
What does a gamma radiation reaction look like?
-1 reactant and 2 products
R:
Element
P:
Same element
Photon (with no charge or mass)
What are the results of a beta decay?
Beta minus: atomic number INCREASES by 1, mass STAYS THE SAME
Beta positive: atomic number DECREASES by 1, mass STAYS THE SAME
What does a beta MINUS decay reaction look like?
-1 reactant and 2 products
R:
Neutron
P:
Proton
Electron/beta particle(no mass, -1 charge)
What does a beta POSITIVE decay reaction look like?
-1 reactant and 2 products
R:
Proton
P:
Neutron
Positron (no mass, +1 charge)
What does alpha decay result in?
Mass DECREASES by 4
Atomic number DECREASES by 2
What does a alpha decay reaction look like?
-1 reactant and 2 products
R:
Element
P:
Element with mass down 4, atomic number down 2
Alpha particle (mass 4, atomic number 2)
What is emanation?
The process of isotopes emitting radiation
Radioactive isotopes can emit gamma rays(photons), alpha, and beta particles
