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Atomic Theory Project
Transcript of Atomic Theory Project
Death: August 30, 1940 John Dalton Born: September 6, 1766
Died: July 27, 1844 Ernest Rutherford Born: August 30, 1871
Died: October 19,1937 Niels Bohr Born: October 7, 1885
Died: November 18, 1962 Erwin Schrodinger Born: August 12, 1887
Died: January 4, 1961 Dmitri Mendeleev Born: February 8, 1834
Died: February 2, 1907 Henry Moseley Born: November 23, 1887
Died: August 10, 1915 Dalton's theory was based upon the fact that you could distinguish atoms of different elements by their various masses.
1)All matter is made of atoms.
2)Atoms are indivisible and indestructible.
3) All atoms of the same element are identical in mass and properties.
4) When atoms are rearranged a chemical reaction occurs.
*He stated his theory in 1803 in a lecture he was giving to the Royal Institution. Cathode Ray:
Thomson did not discover the cathode ray. He stated that cathode rays were negatively charged particles in motion. He concluded this by performing several experiments in 1897 in which he used a cathode ray tube and a conductor to separate the cathode ray and the negative charge. He discovered that the negatively charged electrons and the positive rays in the cathode ray, which were later named protons by Rutherford, had an equal mass. Gold Foil Experiment(1909-1911):
Ernest Rutherford conducted the Gold Foil Experiment in which he compared his theory of how particles would pass through metal foil to how a bullet would penetrate a bag of sand. He expected the particles to penetrate the metal foil since they moved quickly and had a considerable mass. However, they would scatter slightly due to collision with the atoms through which they passed. He proposed the nuclear atom as a result of this experiment. Niels Bohr received the Nobel Prize in 1922 for Physics on his work on the structure of the atom.
The Bohr model of the atom, proposed in 1913, shows Bohr's proposition that electrons have a fixed orbit around the nucleus. It explained how electrons could jump to another energy level using energy and when it jumped back it would release energy. In 1869, Mendeleev arranged the periodic table first by mass number. He later put the elements into periods that increased in atomic mass as you went right. Then he put the elements in columns so that elements that shared similar properties were under each other. He also left gaps for elements that were yet to be discovered. In 1913, Henry Moseley arranged the periodic table according to the atomic number of the elements (number of protons). He determined that the elements should be arranged by their atomic number by observing that the energy of x-rays given off by elements increased with each successive element. The energy given off by the elements depended on the number of protons in the nucleus so to arrange the elements by atomic number made sense. Alkali Metals:
Francium (Fr) Located in Group 1, alkali metals are elements that, when combined with water, form hydroxide ions. Their valence shell holds 1 electron, so to satisfy the octet rule they will lose their 1 valence electron and become a +1 cation. They are very reactive metals and react easily with other elements. Alkali metals are soft, malleable, and ductile. Also, they are good conductors of heat and electricity. They have low melting and boiling points. They also are less dense than most elements. Alkali metals are used in batteries, rubber products, and dyes. Pl Plum Pudding Model:
Thomson proposed the plum pudding model in 1904 that showed the volume of the atom to be composed primarily of the larger positive portion (plum pudding). Dispersed throughout the positive mass were smaller electrons (raisins) that maintained the neutral charge. Atomic Model:
Using the results of his Gold Foil Experiment, Rutherford proposed his ideas of what was in a atom and where it was located. In 1911, Rutherford proposed that the positive charge of an atom was located at the center of the atom, also known as the nucleus, and took up a small volume. He also said that all of the mass of an atom was located there and that the majority of the volume of the atom was filled by electrons that took up the rest of the empty space. In 1920 he proposed the neutron as the third particle to make up an atom. Alkaline Metals: Beryllium(Be), Magnesium(Mg), Calcium(Ca), Strontium(Sr), Barium(Ba), and Radium(Ra) Located in Group 2, Alkaline Earth Metals have 2 electrons in their valence shell. In order to satisfy the octet rule they lose 2 electrons and become a +2 cation. They are shiny solids that conduct heat or electricity. Also, they can be formed into sheets. Calcium is used to build strong bones and as a nutrition supplement. Magnesium is used in alloys for construction. Strontium is used in fireworks. Transition Metals: Groups 3-12 Groups 3-12 consist of Transition Metals. All Transition Metals have 2 electrons in their valence shell. They are good conductors of heat and electricity, malleable, and ductile. They also have high melting points (except mercury which is a liquid at room temperature) and high densities. Transition Metals are used in computers, nails, and the wheels of chairs. Halogens: Fluorine(F), Chlorine(Cl), Bromine(Br), Iodine(I), and Astatine(At) Group 17 consists of Halogens that have 7 electrons in their valence shell. By gaining an electron they satisfy the octet rule and become a -1 anion. It also is the only group to have all 3 states of matter shown by its elements. They have low boiling and melting points. Also they are poor conductors of heat and electricity since they are non-metals. Fluorine is used in toothpaste, chlorine is used in pools and sewage treatment plants, and iodine is used in medicines. Nobel Gases: Helium(He), Neon(Ne), Argon(Ar), Krypton(Kr), Xenon(Xe), and Radon(Rn) Noble Gases are located in Group 18 and are called "noble" due to the fact that they have a full valence shell so they won't be a cation or an anion. They are non-metals that are very nonreactive and colorless. Krypton is used in lasers and Argon is used in lighting. The Copenhagen Model Of The Atom(Cloud Model):
In 1926, Schrodinger proposed a model of the atom that showed the probable place of electrons in an atom. As you go into the denser region of the cloud there is a higher possibility of finding an electron. He applied the mathematical equations that he himself developed to describe movement of electrons in a given atom and Heinsenberg's uncertainty principle to the model of the atom. The Thought Experiment/ Copenhagen:
The thought proposed by Schrodinger in 1935 stated that somehow a cat was both alive and dead at the same time. In this experiment he was trying to demonstrate the limitations to quantum physics. He stated that though a quantum particle could be in more than one different quantum state at the same time, a object with a bigger number of atoms, such as a cat, could not be in more than one different state. He thought of an experiment in which a radioactive atom, which is connected to a vial of poison, is locked inside a box with a cat. If the atom began to decay it would trigger the release of the poison, thereby killing the cat. If the box is closed it is unknown if the atom has decayed or not. This means it can be in the decayed and non-decayed state. Therefore, the cat is both alive and dead, which does not occur in classical physics.