Unanswered Periodic Properties Questions

At ordinary temperature and pressure,chlorine is a gas,bromine is a liquid while iodine is a solid. Is this because of their specific heat,intermolecular force among the molecules,density or stability? ...

Arrange O2-,F-,Na+ and Mg2+ in ascending order in terms of their: a)Effective nuclear charge b)Atomic size c)Ionization potential d)Electron affinity ...

At 200 degree Celsius pcl5 dissociate as follows pcl5= pcl3 +cl2 .it was found that the equilibrium vapours are 62 times as heavy as hydrogen .The degree of dissociation of pcl5 at 200 degree Celsius is ...