Using a reaction as an example, explain why bromine is more reactive than iodine in terms of electrons.

bromine + sodium iodide --> sodium bromide + iodineBr₂ + 2NaI --> 2NaBr + I₂ Both bromine and iodine atoms have 7 electrons in their outer shells, a full shell contains 8 electrons. Bromine has 4 shells, whereas iodine has 5. Positively charged protons are found in the nucleus of the atom. For bromine or iodine to react, each atom needs to gain an electron to fill up its shell so that it is in a more stable state. Since bromine has fewer shells, its outer shell is closer to the nucleus so, there is a stronger force of attraction of the positively charged nucleus on the outer shell of electrons. This makes it much easier for bromine to gain an electron to the outer shell.This then makes bromine more reactive than iodine, and so it will displace the iodine in the sodium iodide to form sodium bromide.