the United States

Nucleus. The nucleus of an atom is its central body, holding particles called protons and neutrons. The number of protons in the nucleus is the atomic number of the element; for example, a helium atom always has two protons, and carbon always has six.

Consider the element helium. Its atomic number is 2, so it has two protons in its nucleus. Its nucleus also contains two neutrons.

Periodic Table app

Helium is abundant in space, where it’s produced as a product of the fusion reaction inside stars such as the sun. The naturally occurring helium on Earth, though, comes from a different sort of process. Deep inside the Earth, radioactive elements such as uranium and thorium decay and turn into other elements.

Once the gas leaks into the atmosphere, it is light enough to escape the Earth’s gravitational field so it bleeds off into space, never to return. We may run out of helium within 25–30 years because it’s being consumed so freely.

If you wanted to invest in helium, the simplest path would be to buy up stock in a helium producer or storage company. A good derivative play would be to invest in clowns.

nucleus

Discovery of Electrons, Protons and Neutrons

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.

electromagnetic force

The strong nuclear force

Protons and neutrons aren’t electrically attracted to each other, but when they get close enough they can exchange particles called mesons and become bound together by the strong force. Protons electrically repel each other because of their positive charge.

The two electrons in a covalent bond usually have opposite spins, so they attract each other because of exchange force. However, they repel each other because of Coulomb forces, the resultant force makes them stable. Exchange force exists in atoms, molecules and as well as in solids.

First, electrons repel against each other. Particles with the same charge repel each other, while oppositely charged particles attract each other. Figure 1: a) The two electrons are placed together and repel each other because of the same charge. b) The two protons are repelling each other for the same reason.

Most of an atom’s volume is filled with matter. Electrons determine the atom’s size. With electrons on the surface, atoms repel one another when they come too close. Thus, electrons determine the space that an atom occupies.

Electrons have a negative charge. The charge on the proton and electron are exactly the same size but opposite. Neutrons have no charge. Since opposite charges attract, protons and electrons attract each other.

But an interesting thing can happen when the two atoms get close together. The electron in each atom starts to notice the proton of the other atom. As a result, it becomes attracted not only to its own proton, but to the proton of the other atom as well. And electrons tend to repel each other.

Due to electrostatic repulsion the two electrons will repel each other as they both possess similar charges (lets leave gravitational attractive force out of the picture).

That is, a proton and an electron will attract each other. The closer they are together, the stronger this attraction will be. Two protons (or two electrons) will repel each other. And again, the closer together they are, the stronger the repulsion.

An atom is composed of three types of subatomic particles: the proton, neutron, and electron. Protrons and neutrons have similar masses and electrons are much lighter (over 1,000 times lighter). Protons and electrons have equal and opposite charges while neutrons have no charge.

According to Coulomb, the electric force for charges at rest has the following properties: Like charges repel each other; unlike charges attract. Thus, two negative charges repel one another, while a positive charge attracts a negative charge. The attraction or repulsion acts along the line between the two charges.