Nuclear physics has given us a chart of which nuclei are known and which are stable. The details are manifold and make up the entire field of nuclear physics. On exceptional occasions, a nucleus fracture into multiple pieces. A nucleus might spit out some particles, or it might even suck in others. Unstable nuclei are difficult to form and spontaneously break apart. For example, you'll never see a hydrogen atom with twelve neutrons. Part of this is how those nuclei were created and part of this is stability. Some numbers are more common than others.

Silicon has fourteen, and Iron has twenty-six protons.Ītoms of the same element might have different numbers of neutrons. You can revisit the table and know immediately how many protons a given nucleus has. The chemical elements - familiar from the periodic table - are determined by the number of protons in a the nucleus of an atom. In some sense the nucleus is so much smaller and denser than the electron cloud because the nuclear force is so much stronger that the electric force. Different atoms have different numbers of both, and they are all bound together by a strong force - the aptly named strong nuclear force - a force much stronger than the electromagnetic force that binds molecules together. The nucleus is made up of smaller particles: protons and neutrons. So the nucleus is really, really small and really, really dense. Actually, the nucleus is more like a grain of clay atop of the pitcher’s mound.ĭespite this small size, the nucleus makes up over 99% of the mass of the atom. It's so small that if the atom were a baseball stadium, the nucleus is smaller than the baseball at the pitcher’s mound. It’s much, much smaller than the atom itself: about 100,000 times smaller. The nucleus is the hard center of the atom.

Today, we are talking about that nucleus. When we think about atoms, we model them as a nucleus surrounded by an electron cloud. Or maybe ten billion! Atoms are too small to rationalize. Atoms are so small that its hard for our minds to comprehend it, but if you need a reference point take your height and divide it by a billion. We are made of molecules, and molecules are made of atoms, and atoms are really, really small.

Nucleus atom