The smallest unit of matter that can exist of an element.
A molecule containing two or more different atoms bound together.
A fundamental substance that has a unique atomic number on the periodic table.
A form of matter that has mass but no definite shape, and can be either compressed or expanded to fill an infinite volume.
A different form of an element that varies by the number of neutrons in the nucleus.
A form of matter which has mass, occupies a volume, and flows to adopt the shape of its container.
A form of matter which has a definite shape and volume.