Stable & unstable nuclei

Question 1

Strong nuclear force

Answer 1

• Overcomes electrostatic force of repulsion between protons in nucleus, keeps protons & neutrons together
• Range: 3-4 femtometers (fm), 1fm = 10^-15 (diameter of small nucleus
• Same effect between: 2 protons, 2 neutrons, proton & neutron
• Attractive force 3-4 fm to 0.5 fm, Repulsive force prevents protons & neutrons, pushed together

Question 2

Radioactive decay

Answer 2

Alpha

• Helium nucleus
• Nucleon number decreases by 4
• Atomic number decreases by 2
• Different element created

Beta
-Fast moving electrons
-Neutron in nucleus changing to proton
-Antineutrino emitted (no charge), hardly interacts
-Atomic number increases by 1, nucleon number stays same
-Different element created
0
   ß (ß-)
-1

Gamma

• Em radiation from unstable nucleus, too much energy
• No mass & charge

Question 3

Elusive particles

Answer 3

• Beta particles released Ke up to a maximum, depended on isotope
• Each unstable nucleus lost certain amount of energy in the process
• Energy only conserved when neutrinos & antineutrinos carried energy away