The Atom: Building Blocks of The Universe

1. The Atom: Building Blocks of The Universe By: Daniel, Lauren, Kristen W., Kristen P.

2. Reason • During this presentation we will explain all the different principles and models, of certain philosophers, derived to lead us to what we now know. We will also explain the evolution of atomic theory. Atoms are unable to be seen by the naked eye, which is why scientists have been forced to create theories and conduct experiments, to obtain some knowledge towards understanding the complex structure of the atom.

3. Atomism • Atomism is the theory, that all the objects in the world are composed of very small indestructible particles called atoms. In other words the society was built with nothing more than indivisible building blocks. The word atomism derives from the ancient Greek word atomos which means "that which cannot be cut into smaller pieces".

4. The Four Elements During the fifth century B.C., according to a Greek philosopher named Empedocles, all matter is composed of four elements: Earth, Fire, Air, and Water. Fire and air are outwardly reaching elements, reaching up and out, while on the other hand earth and water turn down. He believed that all these elements were not only physical manifestations but also spiritual. They were associated with four Greek gods: Zeus, Hera, Hades, Nestis.

5. The Solid Sphere Model The earliest model of the atom pictured it as a solid sphere of positive charge with negatively charged electrons embedded in them like raisins in a cookie. John Dalton expanded on the ideas of the Geek philosophers. He stated that atoms had their own size, shape, and mass

6. Plum Pudding Model The Plum Pudding model of the atom was proposed by J.J. Thomson, the discoverer of the electron in 1987. The plum pudding model was proposed in March, 1904 before the discovery of the atomic nucleus. In this model, the atom Is composed of electrons surrounded by a soup of positive charge to balance the electron’s negative charge, like plums surrounded by pudding. The electrons were thought to be positioned throughout the atom, but with many electron structures possible, particularly rotating rings. Instead of a soup the atom was said to have a soup of a positive charge.

7. Planetary or Nuclear Model British physicist Ernest Rutherford proposed this model in 1911. The model described the atom as a tiny, dense, positively charged core called a nucleus, in which nearly all the mass is concentrated around which the electrons circulate at some distance, much like planets revolving around the sun. The Rutherford atomic model has been also called the nuclear atom. This experiment was basically just a representation of his gold foil experiment.

8. The Orbital Model The atomic orbital model is the currently accepted model of how the electrons are placed around the nucleus in an atom. It is Also referred to as the Wave Mechanics model. In the atomic orbital model, the atom consists of a nucleus surrounded by orbiting electrons. These electrons exist in atomic orbitals, which a set of quantum states of the negatively charged electrons trapped in the electrical field generated by the positively charged nucleus. In example they are in a form that is similar to our solar system.

9. Quantum Mechanical Model At the end of 19th century, physicists knew there were electrons inside atoms, and that the wiggling of these electrons gave off light and other electromagnetic radiation. But there was still a curious mystery to solve. Physicists would heat up different elements until they glowed, and then direct the light through a prism... This is what Sun iight looks Like when it is shown through a prism. For an example: Hydrogen only Gives off these Colors of the Spectrum. But when scientists looked at the light coming off Of another element, they didn’t see the whole element, Instead they got bright lines of certain colors, or “visible light.” To explain the spectral line puzzle, Bohr came up with an excellent model of the atom Which had electrons orbiting around a nucleus. He came up with an extraordinary rule That electrons can only be in “special” orbits. All other orbits were just not possible. They could “jump” between these special orbits, however when they did do this they Would wiggle a little bit which would cause radiation. Which causes bursts of light called Photons.

10. THE END