Sodium’s elemental is Na. The science memes that have been all around the Internet will tell you that “Na Na Na NA NA” will or should be immediately followed by “Batman!”. This is pretty much the only connection I have. A bad pun will always win with me.
Magnesium is a relatively volatile easily oxidized element that is relatively abundant as alkaline metals go. As vipers make up one of the most abundant species of snake, it seemed to be a good match. Some Vipers spit venom; some inject it with their bite. Quite a few give birth to live young, a rarity in reptiles. Though none exist in Australia despite our reputation for venomous reptiles, most of our venomous snakes are Elapidae but not true vipers. Some even belong to a “viper like” family that is possibly a sign of some convergent evolution (though a biologist might tell me I am wrong here).