Nuclear Chemistry

Inorganic Chemistry May 12, 2015

Atomic Nuclei and Nuclear Stability

Describe how the strong force attracts nucleonsRelate binding energy and mass defectPredict the stability of a nucleus by considering factors such as nuclear size, binding energy, and the ratio of neutrons to protons in the nucleus

Nuclear forces

Nucleons and nuclide

Nuclear forces

Protons and neutrons are nucleonsA specific number of protons and neutrons are described as a nuclideAn isotope has the same atomic number but different mass numberIsotopic notation

Mass # 25

Mg Chemical SymbolAtomic # 12

Nuclear Forces

Strong force exists when nucleons are close togetherThe strong force must overcome the electrical charge of the protonsThree quarks make up nucleonsQuarks are in flavors

Nuclear Forces

Binding energy and Mass Defectseparate nucleons nucleus + energy

Nuclear binding energy is the energy associated with the loss of mass, mass defect, from the combining of nucleons

Eo = mc2

2.73 x 10 12 J/mol 42He

Nuclear Forces

Nuclear Forces Stability

1. Except for 11H and 3

2He, all stable nuclei have a number of neutrons that is equal to or greater than the number of protonsA nucleus that has an N/Z number that is too large or too small is unstable. Gradual increase from 1 to 1.5Nuclei with even number of neutrons and protons are more stableNuclei that have magic numbers of protons and neutrons [2,8,20,28,82,&126]

Review Problems

1-12 Skip 2’s page 6471-9 Skip 2’s page 874

Mass of a proton 1.672614 x 10-27 kgMass of a neutron 1.6749543 x 10-27 kgSpeed of light 3.00 x 108 m/s