Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. A chemical weapon is a device that uses chemicals formulated to inflict death or harm to human beings. They may be classified as weapons of mass destruction, and have been "condemned by the civilised world". They are separate from biological weapons (diseases), nuclear weapons (which use sub-nuclear fission) and radiological weapons (which use radioactive decay of elements). Chemical weapons can be widely dispersed in gas, liquid and solid forms and may easily afflict others than the intended targets. Nerve gas and tear gas are two modern examples. Learn more about chemical warfare and weapons, in this book.