This brief entry describes the hydrogen ion, strictly, as the nucleus of a hydrogen atom separated from its accompanying electron. The hydrogen nucleus is made up of a particle carrying a unit positive electric charge, called a proton.

Can you identify the steps of mitosis in this video? The video shows the process of the nucleus of a eukaryotic cell dividing in real time. [0:19]

Wikipedia provides the definition of the term, "Atomic number," a term used in chemistry and physics to represent the number of protons in the nucleus of an atom.

Provides a definition and explanation of fission, the splitting of a heavy nucleus into two roughly equal parts, and fusion, the process where two nuclei combine together to form a larger nucleus.

Learn how you can find the probability of survival but cannot predict the time of disintegration of an atomic nucleus with this simulation. This site is best viewed with Internet Explorer.

Describes the structure and functions of the membrane surrounding a cell nucleus.

Using examples, this page defines and explains what happens in the process of alpha decay.

A brief explanation of the process of gamma decay is provided.

Brief exploration of approximate symmetries used to describe and predict the behavior of nuclei.

Brief explanation of nuclear energy levels whose location and properties are governed by the rules of quantum mechanics.

Site provides the ABC's of nuclear science including radioactivity and gamma decay to fission and comic rays.

All matter is made of atoms! And atoms are made of even smaller more fundamental particles. Atoms are not shiny little rigid spheres as we depict in drawings and simulations; they're more like a squishy storm of tiny particles swirling...

A crossword to help review the terms and definitions associated with organelles.

Explains how DNA contains genetic material and how it is housed in chromosomes. This lesson is 2 of 5 in the series titled "DNA."

Explains how DNA contains genetic material and how it is housed in chromosomes. This lesson is 1 of 5 in the series titled "DNA."

Explains how DNA contains genetic material and how it is housed in chromosomes. This lesson is 4 of 5 in the series titled "DNA."

Describes the different parts of a plant cell.

Explains how plant and animal cells are different and describes the organelles in a plant cell.

Provides a labeled diagram of a plant cell and descriptions of the characteristics and functions of many of its organelles.

This website provides a short but detailed definition of atomic radii. Also shows the atomic radius plotted against atomic number.

Explains cell structure and function and describes the parts of a cell.

From the Mad Scientist Network web site. Using a question and answer format, this page provides a thorough discussion of fusion reactions. Fusion and fission are compared and contrasted and the mechanisms which must occur to initiate and...

This site from the encyclopedia Wikipedia provides a basic definition for what the atomic radius is, and an explanation of what covalent and metallic radii are.

This lesson explains the difference between Eukaryotic and Prokaryotic cells. It is 1 of 4 in the series titled "Eukaryotic vs. Prokaryotic Cells."