The nucleus contains two types of subatomic particles, protons and neutrons. The protons have a positive electrical charge and the neutrons have no electrical charge.

The Atom’s Charge As long as the number of protons in an atom equals the number of electrons, the atom remains uncharged, or neutral. When an atom gains or loses electrons, it becomes an electrically charged ion.

The neutron is a neutral particle, which is stable only in the confines of the nucleus of the atom. Outside the nucleus, the neutron decays with a mean lifetime of about 15 min.

Atomic Particles The nucleus (center) of the atom contains the protons (positively charged) and the neutrons (no charge). The outermost regions of the atom are called electron shells and contain the electrons (negatively charged).

Neutron

electron

Neutrons are required for the stability of nuclei, with the exception of the single-proton hydrogen nucleus. Neutrons are produced copiously in nuclear fission and fusion. They are a primary contributor to the nucleosynthesis of chemical elements within stars through fission, fusion, and neutron capture processes.

A neutron is made of 3 quarks, one up quark, and 2 down quarks and many many “intermediate particles” called gluons which carry the interaction between the quarks. These gluons are exchanged very often, so the quarks feel each of other. Neutrons do not always decay….

Electrons are attracted to any positive charge by their electric force; in an atom, electric forces bind the electrons to the nucleus. In some respects, the electrons in an atom behave like particles orbiting the nucleus. In others, the electrons behave like waves frozen in position around the nucleus.

n

With U-238, the neutron needs to be slowed down, or “thermalized”. This is done using heavy water, or water made from hydrogen with extra neutrons. The free neutrons hit the water atoms and transfer some of their kinetic energy to the water, heating it up.

A neutron star is about 20 km in diameter and has the mass of about 1.4 times that of our Sun. This means that a neutron star is so dense that on Earth, one teaspoonful would weigh a billion tons! It collapses so much that protons and electrons combine to form neutrons. Hence the name “neutron star”.

: an uncharged elementary particle that has a mass nearly equal to that of the proton and is present in all known atomic nuclei except the hydrogen nucleus.

center core

1 : a proton or neutron especially in the atomic nucleus. 2 : a hypothetical single entity with one-half unit of isospin that can manifest itself as either a proton or a neutron.

Benjamin Franklin

Electrons are the negatively charged particles of atom. Together, all of the electrons of an atom create a negative charge that balances the positive charge of the protons in the atomic nucleus.

Protons and Electrons A proton carries a positive charge (+) and an electron carries a negative charge (-), so the atoms of elements are neutral, all the positive charges canceling out all the negative charges. Atoms differ from one another in the number of protons, neutrons and electrons they contain.

Benjamin Franklin who experimented with electricity in the middle 18th century made an arbitrary choice: When a. rubber rod that is rubbed with cat’s fur the charge on the rod is called negative and when a glass rod is rubbed with silk the charge on the rod is called positive. It could have been the other way around….

There are two types of electric charge: positive and negative (commonly carried by protons and electrons respectively). Like charges repel each other and unlike charges attract each other. In ordinary matter, negative charge is carried by electrons, and positive charge is carried by the protons in the nuclei of atoms.

What happens if an electron is near a proton? When an electron is near a proton the electron and proton experience an attractive force. 2. The net electric field is positive, when q2 approaches 0C the force of attraction between the electric field and the negatively charged particle becomes weaker.