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Subatomic particles are the basic units of an atom. The earliest models of the atom described three subatomic particles: protons, electrons, and neutrons [1]. The nucleus hosts the two biggest (size) subatomic particles (protons and neutrons) while the electrons orbit around the nucleus.
Nucleus
Protons were first discovered by Earnest Rutherford in 1918 [2]. The protons have a positive charge, neutrons have a neutral (no) charge. Both are relatively identical in size. What makes a hydrogen atom a hydrogen atom? What makes carbon different from magnesium? The answer is the number of protons. The number of protons in the nucleus of an atom determines what kind of atom it is. For example all hydrogen atoms have one thing in common. They all have one proton in their nuclei. Thats it! All carbon atoms have one thing in common. They all have 6 protons in their nuclei. Every single potassium atom has 19 protons in their nuclei. The number of protons determines what element it is.
Nucleons are the ‘buddys’ of protons and are said to hold the protons together. Scientists have found particles that are smaller then subatomic particles. For example, particles called quarks have been found inside the proton [3]. There are two up quarks and one down quarks. However, there are more known quarks then that. There is the top quark, strange quark, and the top and bottom quarks [4].
Electrons
The electron is a negatively charged subatomic particle discovered by J. J. Thomson. The Irish physicist George Stoney introduced the term in 1891. [5]
Electrons were first discovered by a physicist in England by the name of J.J. Thomson. He knew there had to be negatively charged particles in an atom. The following is information on the history of electrons:
"The word "elektron" in Greek means amber, the yellow fossilized resin of evergreen trees, a "natural plastic material" already known to the ancient Greeks. It was known that when amber was rubbed with dry cloth--producing what now one would call static electricity--it could attract light objects, such as bits of paper." [6]
These negatively charged particles orbit around the nucleus, which is called an electron cloud [7]. This orbiting doesn't happen at random; the electrons have certain energy levels that they must abide to. The size of these electrons are said to be 1800 times smaller then a proton or neutron [8]. In a neutral atom, the number of protons and neutrons are the same, because their charges cancel each other out. However, not all atoms are neutral.
Ions
An ion is a particular atom that have electrons added or removed from it. If electrons are added, then the atom is now negative; if electrons have be removed, then the atom is positive. Each kind of ion has a certain name. A positive ion is called cation (cat-eye-on); a negative ion is called a anion. Elements that have pure anions or cations has its name changed. For example, when a fluorine atom gains one electron, its new name is called a fluoride ion. When a bromine atom gains an electron, its new name becomes bromide ion [9]. It is possible to combine ions and create chemical compounds. For example, if you take sodium ions and combine them with chlorine ions, you create a well known substance on the kitchen table; salt.
Video Tutorials
This video introduces the concept of a divisible atom and calculating the number of neutrons and isotopes.
References
- ↑ NDT Resource Center (n.d.) Subatomic Particles retrieved February 5, 2009, from http://www.ndt-ed.org/EducationResources/HighSchool/Radiography/subatomicparticles.htm
- ↑ Zimmerman Jones, Andrew. (n.d.) Protons retrieved February 5, 2009, from About.com http://physics.about.com/od/glossary/g/proton.htm
- ↑ David Lindley (n.d.) The Proton's Strange Magnetism retrieved February 5, 2009, http://focus.aps.org/story/v16/st7
- ↑ Nave, R. (n.d.) Quarks retrieved February 5, 2009, from http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/quark.html
- ↑ Julian T. Rubin
- ↑ Stern, PhD. David P. and Peredo, PhD. Mauricio. 2001, November 25, History of the Electron retrieved February 8, 2009, from http://www-istp.gsfc.nasa.gov/Education/whelect.html
- ↑ Rader, Andrew. (n.d.) Charge It! retrieved February 8, 2009, from http://www.chem4kids.com/files/atom_electron.html
- ↑ Russell, Randy. 2008, July 30, Electron retrieved February 5, 2009, from http://www.windows.ucar.edu/tour/link=/physical_science/physics/atom_particle/electron.html
- ↑ Zumdahl, S.S., Zumdahl, S. L., DeCoste, D. J. (2006). World of Chemistry. Houghton Mifflin Company.
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