Isomerism is the phenomenon whereby certain compounds, with the same molecular formula, exist in different forms owing to their different organisations of atoms. The concept of isomerism illustrates the fundamental importance of molecular structure and shape in organic chemistry.
By signing the nuclear deal, Iran has given up that nuclear umbrella for as long as two decades and made the case for the United States to further strengthen the conventional military capacities of Israel and the GCC.
A profile of the Iranian politicians at the forefront of the nuclear deal, and the stances they adopted over time. After 18 days of marathon talks in Vienna, Iran has reached a deal with P5+1 nations - China, France, Russia, the UK, the US and Germany - on its nuclear programme.