Thursday, April 30, 2015

The binding energy of magnesium is 198.25 MeV, find its atomic mass.

An atom of magnesium has 12 neutrons, 12 protons and 12 electrons. The mass of an electron is `9.10938356*10^-31` kg, the mass of a proton is `1.6726231*10^-27` kg and the mass of a neutron is `1.6749286*10^-27` kg.


The mass of an atom is less than the total mass of the constituent particles. This decrease in mass is equivalent to the binding energy of the atom. The equation `E = m*c^2` gives the mass energy relation...

An atom of magnesium has 12 neutrons, 12 protons and 12 electrons. The mass of an electron is `9.10938356*10^-31` kg, the mass of a proton is `1.6726231*10^-27` kg and the mass of a neutron is `1.6749286*10^-27` kg.


The mass of an atom is less than the total mass of the constituent particles. This decrease in mass is equivalent to the binding energy of the atom. The equation `E = m*c^2` gives the mass energy relation where E is the energy, m is the mass and c is the velocity of light. The binding energy of magnesium is 198.25 MeV.


One MeV is equal to `1.6022*10^-13` J. 198.25 MeV is equal to `3.176315*10^-11` J. 


This is equivalent to a mass `3.176315*10^-11/(299792458)^2` = `3.534127063*10^-28` kg. The total mass of 12 electrons, protons and neutrons is `12*(9.10938356*10^-31+1.6726231*10^-27+1.6749286*10^-27)` = `4.018155166*10^-26` kg. Subtracting the mass equivalent of the binding energy gives `4.018155166*10^-26-3.534127063*10^-28` = `3.982813895*10^-26` kg.

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