a class="link" rel="nofollow" href=" Sodium does not react easily with oxygen at a room temperature so it has to be heated up a little for the reaction to start.br br Since air is mostly oxygen once the reaction starts it gets pretty violent and the piece of sodium explodes.br br ---br It's Never too Late to Study:br a class="link" rel="nofollow" href=" ---br Notice: This video is copyright by its respectful owners.br The website address on the video does not mean anything.