Suppose you were trying to find a substitute for na+ in nerve signal transmission. where would you begin your search? what ions would be most like na+? for each ion you propose, explain the ways in which it would be similar to na+ and the ways it would be different. use periodic trends in your discussion.

The human eye contains a molecule called 11-cis-retinal that changes shape when struck with light of sufficient energy. the change in shape triggers a series of events that results in an electrical signal being sent to the brain that results in vision. the minimum energy required to change the conformation of 11-cis-retinal within the eye is about 164 kj/mol.