In chemistry and physics, an atom is the smallest particle still characterizing a chemical element.
An atom consists of a dense atomic nucleus of positively-charged protons and electrically-neutral neutrons, surrounded by a much larger electron cloud consisting of negatively-charged electron. An atom is electrically neutral if it has the same number of protons as electrons. The number of protons in an atom defines the chemical element to which it belongs, while the number of neutrons determines the isotope of the element.
Atoms are the basic building blocks of matter that make up everyday objects. A desk, the air, even you are made up of atoms!
There are 90 naturally occurring kinds of atoms. Scientists in labs have been able to make about 25 more.
Celebrate what is not typically visible to the naked eye by wearing the Digital Militia Atom Symbol shirt, which displays the international symbol for the atom, depicting three well-defined electron orbits around a nucleus.