Sodium

chemistry · elements · metal · ocean

Salt from the sea. Sodium is the reason ocean water is salty! Sodium ions have been washed out of rocks over millions of years and collected in the ocean, making it one of the two most common dissolved things in seawater.

Shiny but risky. Sodium is a soft, silvery-white metal that reacts so intensely with air and water that it can actually burst into flames if you're not super careful with it. Scientists have to keep it safe in special oil or containers.

Element number 11. Sodium has the symbol Na and sits in group 1 of the periodic table with other alkali metals. It's the sixth most abundant element in Earth's crust, hiding in rocks called feldspars and halite.

Your body needs it. Even though sodium can be dangerous in its pure metal form, your body actually uses sodium ions every single day to help your muscles work, your nerves send signals, and keep your water balance just right.

Only one stable version. Sodium has one stable form called sodium-23, which means most sodium atoms stay the same forever instead of breaking apart into other elements.