A gas is one of the four states of matter. In a gas, the molecules move freely and are not attached to each other. This makes it different from a liquid where the molecules are loosely attached to or touching each other. It is also different from a solid where the molecular bonds are strong and hold the molecules together in one shape.
A gas does not have only one volume like a liquid or solid does. Instead, gas can expand until it fills whatever container it is in.
In a pure gas, each molecule may be made of an individual atom. It may be elemental, where each molecule is made of more than one of the same atom bound together. It may be compounds where molecules are made of many types of atoms together. An example of a monoatomic gas is neon, an example of an elemental gas is hydrogen and an example of a compound gas is carbon dioxide.
A gas mixture contains a mix of any of the above types, for example air which is 78% nitrogen, 21% oxygen, less than 1% argon, around 0.03% carbon dioxide and more other in very small quantities.[1]
Poison gases were used as chemical weapons in WWI.
- ↑ "Composition of Air". mistupid.com. Retrieved 2024-01-18.