Created by kchenofan1995 on Nov 10, 2010
Last updated: 12/14/10 at 05:59 AM
Erwin Schrodinger showed that electrons are really waves as opposed to particles, which was the previous school of thought. He also helped develop the quantum theory.
Louis-Victor-Pierre-Raymond, 7th duc de Broglie theorized the particle wave duality theory. de Broglie concluded that light acted as both waves and particles depending on the situation and what is measured.
Frederick Soddy worked with Rutherford to explain that radioactivity is due to the transformation of elements. They showed that radioactive elements decay into other elements producing alpha, beta, and gamma radiation. He also showed that radioactive elements may have more than one atomic mass though the chemical properties are identical. He named this concept "isotope", meaning, "same place". Later, JJ Thomson showed that non radioactive elements can also have multiple isotopes.
Nils Bohr theorized that negatively charged electrons orbit around an atom's nucleus, but the nucleus is positively charged. To prove his theory, Bohr constructed what is the currently believed model of the atom, called the Bohr Model.
Ernest Rutherford discovered the nucleus of the atom. His discovery of alpha and beta rays lead him to use uranium to conduct the "Gold Foil Experiment". In this experiment, he found that the atom was mostly empty space but that it contained a tiny center, called the nucleus. Rutherford's model involves a negative electron cloud and a tiny nucleus in the center.
Considered the inventor of quantum theory. In 1899, he discovered a new fundimental constant used to calculate the energy of a photon (light emitted from an electron). He also discovered that, when an element is exposed to extreme heat, the electrons get "excited" and jump to higher energy levels. The extra energy left over is used to create a color. Different elements give off different colors because of the different numbers of electrons moving around.
Marie Curie discovered the element radium (atomic number 88). She also created the electro-meter, which is a measurement tool to measure the levels of radiation in a substance. Curie was the first woman in history to win the Nobel Prize.
Sir Joseph John (J.J.) Thomson’s main contribution to science was his discovery of the electron. His basic theory that he proposed was that the atom was a spherical entity, positively charged, with electrons particles within it.
Dmitri Mendeleev organized the periodic table of the elements. He created the table using different trends and similarities between the different types of elements. His model of the periodic table originally began with organizing the elements by atomic mass, but some elements did not line up correctly. So, he organized them by atomic number (number of protons), which fixed all problems with the table.
Dalton was a pioneer in developing the atomic theory. He proposed that all matter was made of indestructible units, called atoms. He also thought that all atoms of the same element shared the exact same properties, such as mass and volume. He theorized other things about compounds, etc, but these were his two main points in dealing with atoms.
Democritus believed that if you were to break a piece of matter apart over and over again, it would eventually become impossible to divide. He called this smallest particle of matter the atom.
Aristotle believed that there was no smallest particle of matter, like Democritus claimed. He believed that the different elements were all made up of different combinations of the four elements: earth, wind, fire, and water.