Changes

|-

|-

| Mass

| Mass

| 235.04393

| 235.04

| 139.92164

| 139.9

| 90.910203

| 90.9

| 4.03466

| 4.04

|}

|}

The mass of the Uranium atom is 235.04393, and the sum of the masses of the products is 234.866503.  The difference is .177427 amu, or, using the E=mc² equation, 165 million electron volts.  (The generally accepted value for the total energy released by Uranium fission, including secondary decays, is about 200 million electron volts.)

The mass of the Uranium atom is 235.04, and the sum of the masses of the products is 234.9.  The difference is .18 amu, or, using the E=mc² equation, 165 million electron volts.  (The generally accepted value for the total energy released by Uranium fission, including secondary decays, is about 200 million electron volts.)

The insight that the conversion from Uranium to Barium was caused by complete fission of the atom was made by Lise Meitner in December, 1938.  She had the approximate "mass defect" quantities memorized, and so she worked out in her head, using the E=mc² equation, that there would be this enormous release of energy.  This release was observed shortly thereafter, and the result is nuclear power and nuclear weapons.

The insight that the conversion from Uranium to Barium was caused by complete fission of the atom was made by Lise Meitner in December, 1938.  She had the approximate "mass defect" quantities memorized, and so she worked out in her head, using the E=mc² equation, that there would be this enormous release of energy.  This release was observed shortly thereafter, and the result is nuclear power and nuclear weapons.