Atomic Structure and the Periodic Table 2
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- 500 BC coined the term "atomos"
- Democritus
- 1770's Law of Conservation of Matter
- Lavoisier
- 1799 Law of Definite Proportions
- Proust
- 1802 Law of Multiple Proportions & proposed the first Atomic Theory
- Dalton
- 1897 discovered the electron
- Thomson
- 1911 used the gold foil experiment to show the existence of a small, dense center (the nucleus)
- Rutherford
- 1911 used the oil drop experiemnt to calculate the mass of the electron
- Millikan
- 1913 proposed the model of orbiting electrons which would not lose energy and "fall" into the nucleus
- Bohr
- 1916 reported the values of the charge and mass of the electrons
- Millikan
- 1919 research lead to the discovery of the proton & performed earliest articificial transmutation
- Rutherford
- 1932 discovered the neutron
- Chadwick
- 1886 discovered the canal rays (later found to be protons)
- Goldstein
- transmutation
- shooting alpha particles into different isotopes to form new isotopes that break down
- modern atomic theory/model
- Quantum Mechanical Model
- Law of conservation of Mass
- (Lavoisier) matter cannot be created or destroyed
- Law of Definite Proportions
- (Joseph Proust) proportions by mass of the elements in a given compound is always the same [e.g. water 1:8]
- Law of Multiple Proportions
- (Dalton) if two or more different compounds composed of the same two elements are analyzed, the masses of the second elemnt combined with a fixed mass of the first can be expressed as a ration of small whole numbers
- Dalton's Atomic Theory
-
-elements composed of atoms which are indivisible particles
-atoms of same element are alike
-atoms of different elements have different masses
-compounds are formed by atoms of 2+ elements combining in definite whole number ratios - atom
- smallest particle of an element that still reatins the properties of that element
- electron cloud
- outer region containin 7 energy levels
- nucleus
- center core of the atom containing protons and neutrons
- 3 main subatomic particles (even though there are 100+ known subatomic particles)
- protons (+) neutrons electrons (-)
- quarks
- make up protons and neutrons
- lepton
- group electrons belong to
- antiparticle
- exact opposite in charge for every quark and lepton
- 1st subatomic particle discovered (when, by who, and how)
- electron 1897 Thomson using the discharge tube (Crooke's tube, Cathode Ray tube)
- electron charge measured by (who and experiment)
- Millikan and the oil drop experiment
- number of electrons in an atom determines:
- physical and chemical properties
- periodic law
- the elements are arranged in order of increasing atomic number; there is a periodic repition of their physical and chemical properties
- proton
- one of the nucleons made up of two up quarks and one down quark p=uud
- nucleus discovered (who and how)
- Rutherford with the gold foil experiment
- neutrons mass is _________ than protons mass
- slightly greater
- neutrons discovered (by and how)
- Chadwick in transmutation experiment
- when neutron decays...
- a proton, electron, and antineutrino are released
- neutrons made up of
- one up quark and two down quarks n=udd
- isotopes
- different numbers of neutrons in an element
- natural isotopes (#)
- 250
- man-made isotopes (#)
- 1000+
- atomic number (letter representation)
- number of protons in the nucleus of the atom of that element (Z)
- electrons and protons equal in ________ atoms
- neutral
- mass number (letter representation)
- total number of protons and neutrons in the nucleus (A)
- amu
- atomic mass unit= 1/12 mass of Carbon-12
- a relative mass is reported in which each proton and neutron is given the value of
- 1
- mass not a whole number b/c of
- isotopes (average of all naturally occuring isotopes
- periodic table developed by
- Mendelev
- Moseley arranged elements by...
- nuclear charge/atomic number
- horizontal rows
- periods
- vertical columns
- groups/families
- metals
- left of stairstep
- nonmetals
- right of stairstep
- metalloids
- touching stairstep except Aluminum
- representative elements
- A's
- alkali metals
- group 1
- alkaline earth metals
- group 2
- halogens
- group 7
- noble gases
- group 8
- transition metals
- B's
- inner transition metals (location and other name)
- excert (rare earth elements)