- The Joint Comprehensive Plan of Action (JCPOA; Persian: برنامه جامع اقدام مشترک, romanized: barnāmeye jāme’e eqdāme moshtarak (برجام, BARJAM)), commonly known as the Iran nuclear deal or Iran deal, is an agreement on the Iranian nuclear program reached in Vienna on July 14, 2015, between Iran and the P5+1 (the five permanent members of the United Nations Security Council—China, France, Russia, the United Kingdom, United States—plus Germany) together with the European Union.
- Plum pudding model (Wikipedia)
The plum pudding model was the first scientific model of the atom to describe an internal structure. It was first proposed by J. J. Thomson in 1904 following his discovery of the electron in 1897, and was rendered obsolete by Ernest Rutherford’s discovery of the atomic nucleus in 1911. The model tried to account for two properties of atoms then known: that there are electrons, and that atoms have no net electric charge. Logically there had to be an equal amount of positive charge to balance out the negative charge of the electrons. As Thomson had no idea as to the source of this positive charge, he tentatively proposed that it was everywhere in the atom, and that the atom was spherical. This was the mathematically simplest hypothesis to fit the available evidence, or lack thereof. In such a sphere, the negatively charged electrons would distribute themselves in a more or less even manner throughout the volume, simultaneously repelling each other while being attracted to the positive sphere’s center.