Unit 1 – "Atomic Structure" – Flashcards
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Atomos
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greek word for atom- means not able to be divided
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Democritus
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Greek philosopher who developed an atomistic theory of matter (460-370 BC)
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atom
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(physics and chemistry) the smallest component of an element having the chemical properties of the element
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Dalton's Atomic Theory
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1) elements are composed of atoms. 2) atoms of same element are identical, but differ from other elements. 3) elements can mix together 4) atoms only change when mixed with other elements
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J J Thomson
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Discovered the electron
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Plum Pudding Model of the atom
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atoms are balls of positively charged material with negative electrons scattered throught
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Electron
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negatively charged particle; located outside the atomic nucleus
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Cathode-ray tube
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evacuated glass tube in which a stream of electrons emitted by a cathode strikes a fluorescent material, causing it to glow
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Ernest Rutherford
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British physicist (born in New Zealand) who discovered the atomic nucleus and proposed a nuclear model of the atom (1871-1937)
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Gold Foil Experiment
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experiment involving shooting alpha particles at gold foil and observing them going through and bouncing off determining that the nucleus of an atom has a positive charge.
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Nuclear Model of the atom
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created by Ernest Rutherford. Replaced the Plum Pudding Model. Atom is like a miniature solar system with the positive particles in the middle and the negative particles orbiting as the planets do around the center.
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Proton
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positively charged particle of an atom
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Nucleus
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the positively charged dense center of an atom
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James Chadwick
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Discovered the neutron
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Neutron
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a subatomic particle that has no charge and that is found in the nucleus of an atom
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Electromagnetic Force
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the attraction or repulsion between charged particles. electromagnetic force holds negatively charged electrons to the positively charged nuclei of atoms.
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Strong Nuclear Force
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a powerful force of attraction that acts only on the neutrons and protons in the nucleus, holding them together
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N. Bohr
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provided the modern concept of the atomic model (1940)
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Bright Line Spectra
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distinct lines of color given off by an element when viewed through a spectroscope
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Bohr Model
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model of an atom that shows electrons in circular orbits around the nucleus
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Picometer
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a metric unit of length equal to one trillionth of a meter
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Atomic Number
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the order of an element in Mendeleyev's table of the elements
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Mass Number
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the sum of the number of neutrons and protons in an atomic nucleus
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Isotope
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one of two or more atoms with the same atomic number but with different numbers of neutrons
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Protium
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the simplest form of hydrogen that contains 1 proton and no neutrons in the nucleus; the nucleus is surrounded by 1 electron
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Deuterium
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an isotope of hydrogen which has one neutron (as opposed to zero neutrons in hydrogen)
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Tritium
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a radioactive isotope of hydrogen, An isotope of hydrogen that contains one proton and two neutrons per atom.
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Relative atomic mass
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(chemistry) the ratio of the atomic mass of an element to half the atomic mass of carbon-12
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Atomic Mass Unit
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unit of mass for expressing masses of atoms or molecules
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Average atomic mass
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weighted average of the atomic masses for the isotopes of an element
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Mole
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the molecular weight of a substance expressed in grams
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Avogadro's number
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number of representative particles in a mole, 6.02 X 10^23
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Molar Mass
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the mass of one mole of a pure substance
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Scanning Tunneling Microscope
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uses a needle-like probe to measure differences in voltage caused by electrons that leak, or tunnel, from the surface of the object being viewed
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Nucleon
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a constituent (proton or neutron) of an atomic nucleus
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Nuclide
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An atom that is identified by the number of protons and neutrons in its nucleus
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Mass defect
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the amount by which the mass of an atomic nucleus is less than the sum of the masses of its constituent particles
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Albert Einstein
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physicist born in Germany who formulated the special theory of relativity and the general theory of relativity
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E=mc^2
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Einstein's equation proposing that energy has mass; E is energy, m is mass, and c is the speed of light
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Quark
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very small particles of matter that make up protons and neutrons
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Murray Gell-Mann
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American physicist. In 1963 he and George Zweig independently postulated the existence of quarks. He was awarded the 1969 Nobel Prize in physics.
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Nuclear reaction
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(physics) a process that alters the energy or structure or composition of atomic nuclei
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Henri Becquerel
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French physicist who discovered that rays emitted by uranium salts affect photographic plates (1852-1908)
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Marie and Pierre Curie
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Marie (1867-1934) a polish born physicist, and her husband Pierre discovered that radium constantly emits subatomic particles, which means it doesn't have a constant weight.
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Radioactive Decay
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the spontaneous disintegration of a radioactive substance along with the emission of ionizing radiation
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Alpha emission
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radioactive decay of a nucleus that is accompanied by emission of alpha particles
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Alpha particle
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a positively charged particle that is the nucleus of the helium atom
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Beta emission
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release of an electron from the nucleus
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Beta particle
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a high-speed electron or positron emitted in the decay of a radioactive isotope
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Positron emission
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A radioactive decay process in which a proton in the nucleus is converted into a neutron and a positron and then the positron is emitted from the nucleus
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Positron
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A particle with the mass of an electron but a positive charge
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Electron capture
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the process in which an inner orbital electron is captured by the nucleus of its own atom
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Gamma Rays
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Electromagnetic waves with the shortest wavelengths and highest frequencies
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Half-life
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the time required for one half of the atoms of a radioisotope to emit radiation an decay products
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Particle accelerator
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a scientific instrument that increases the kinetic energy of charged particles
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Large Hadron Collider
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Particle Accelerator constructed beneath Geneva.
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Transuranium elements
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the elements in the periodic table with atomic numbers above 92, which all undergo transmutation
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Roentgen
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German physicist who discovered x-rays and developed roentgenography (1845-1923)
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Rem
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(Roentgen Equivalent Man) the dosage of ionizing radiation that will cause the same amount of injury to human tissue as 1 roentgen of X-rays
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Geiger-counter
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a device that uses a gas-filled metal tube to detect radiation
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Radioactive dating
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measurement of the amount of radioactive material (usually carbon 14) that an object contains
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Radioactive tracer
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a radioactive material that is added to a substance so that its distribution can be detected later
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Nuclear fission
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a nuclear reaction in which a massive nucleus splits into smaller nuclei with the simultaneous release of energy
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Nuclear fusion
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a nuclear reaction in which nuclei combine to form more massive nuclei with the simultaneous release of energy
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Manhattan Project
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code name for the secret United States project set up in 1942 to develop atomic bombs for use in World War II
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Enrico Fermi
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Italian nuclear physicist (in the United States after 1939) who worked on artificial radioactivity caused by neutron bombardment and who headed the group that in 1942 produced the first controlled nuclear reaction (1901-1954)
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Chain reaction
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a series of chemical reactions in which the product of one is a reactant in the next
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Trinity, New Mexico
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Place where first atomic bomb was tested
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Los Alamos National Labs
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Site of the Manhattan Project HQ. Place of Atomic Bomb's invention.
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Robert Oppenheimer
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United States physicist who directed the project at Los Alamos that developed the first atomic bomb (1904-1967)
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Hiroshima
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City in Japan, the first to be destroyed by an atomic bomb, on August 6, 1945. The bombing hastened the end of World War II. (p. 797)
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Nagasaki
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Japanese city in which the second atomic bomb was dropped (August 9, 1945).
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Critical mass
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the minimum mass of fissionable material that can sustain a chain reaction
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Chernobyl
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nuclear power plant in Russia that had an explosion in 1986 & released radioactive materials into the air
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Three-Mile Island
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1979 - A mechanical failure and a human error at this power plant in Pennsylvania combined to permit an escape of radiation over a 16 mile radius.
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Fukushima
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When the earthquake hit, the nuclear reactors all automatically shutdown.
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Uranium-235
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an unstable, fissionable isotope of uranium
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Plutonium-239
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a radioactive isotope produced in a breeder reactor and used as a nuclear fuel
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Richard Feynman
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United States physicist who contributed to the theory of the interaction of photons and electrons (1918-1988)
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Lise Meitner
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Swedish physicist (born in Austria) who worked in the field of radiochemistry with Otto Hahn and formulated the concept of nuclear fission with Otto Frisch (1878-1968)
