Nucleus

what is the nucleus?

The nucleus is the small, dense center of an atom where nearly all of its mass is concentrated. It contains protons and neutrons (collectively known as nucleons).

properties

• contains: Protons and neutrons
• charge: positive (due to protons)
• mass: >99.9% of the atom’s total mass
• size: ~1/100,000 of the atom’s total diameter

discovery

ernest rutherford discovered the atomic nucleus in 1911 through his gold foil experiment, showing that the mass and positive charge of an atom are concentrated in a central region.

function of the nucleus

• Houses the atom’s identity through the number of protons
• Maintains mass through neutrons
• Source of radioactive decay in unstable elements
• Plays a central role in nuclear reactions

atomic number and mass number

• atomic number = number of protons
• mass number = protons + neutrons

nuclear stability

• Stable nuclei have a balanced ratio of protons to neutrons
• Unstable nuclei may emit particles (alpha, beta, gamma) in radioactivity

see also

• protons
• neutrons
• electrons
• atomic number
• mass number
• ernest rutherford

disclaimer

This article is intended for academic and educational purposes and is designed for students learning about atomic structure in a MediaWiki environment.