Flashcard Set Preview
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| 1 |
who is responsible for developing the first model of the atom?
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greek philosophers
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| 2 |
what did Empedocles state?
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that all matter was composed of four "elements"-fire, water, air, and earth
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| 3 |
__________thought that all forms of matter were compposed of tiny indivisible particles which...
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Democritus
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| 4 |
what did Democritus do?
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he held that atoms were in constant motion and that they combined with one another in various...
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| 5 |
After Democritus, ____________, opposed the theory of Democritus and instead endorced and adavanced...
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Aristotle
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| 6 |
what did Aristotle do?
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dominated the thinking of scientists and philosophers until the beginning of the 17th century.
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| 7 |
who revived the concept of atoms and proposed an atomic model based on facts and experimental...
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John Dalton, an English school teacher
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| 8 |
what did Dalton's theory describe?
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the idea of a different kind of atom for each element
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| 9 |
How can Dalton's atomic modeel be summed up?
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1. Elements are composed of minute, indivisible particles called atoms2. Atoms of the same...
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| 10 |
why was Dalton's atomic model significant even though it was later proven to be incorrect?
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It showed:1. atoms are composed of subatomic particles2. not all the atoms of a specific element...
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| 11 |
in chemistry, what are models used for?
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to explain the behavior of atoms, molecules, and compounds. To explain new information
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| 12 |
what is a natural law?
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general observations regarding nature into a statement
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| 13 |
what is the law of definite composition?
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a compound always contains two or more elements chemically combined in a definite proportion...
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| 14 |
what is the law of multiple proportions?
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atoms of two or more elements may combine in different ratios to produce more than one compound
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| 15 |
The law of multiple proportions states________________.
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1. the composition of a particular substance will always be the same no matter what its origin...
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| 16 |
what is the difference betwen a law and a model (theory)?
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law- summary of observed behavior, remains constant, do not undergo modificationmodel- an attempt...
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| 17 |
what are the properties of electric charge?
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1. charge may be of two types, positive or negative2. unlike charges attract and like charges...
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| 18 |
who discovered ions?
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michael faraday
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| 19 |
what did michael faraday do?
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he is responsible for the discovery that certain substances when dissolved in water conduct...
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| 20 |
What is an electric current?
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any moving charge
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| 21 |
who extended Faraday's work?
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Svante Arrhenius
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| 22 |
what did Arrhenius reason?
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an ion is an atom (or group of atoms) carrying a positive or negative charge
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| 23 |
what was Arrhenius' experiment?
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upon melting the sodium chloride dissociates or breaks up into charged ions, Na+ and Cl-. The...
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| 24 |
who came after the work on ions of Faraday and Arrhenius?
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G.J. Stoney
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| 25 |
What did G.J. Stoney realize?
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there must be some fundamental unit of electricity as associated with atoms. He named his unit...
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| 26 |
who came with the evidence about the electron?
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J.J. Thomson
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| 27 |
What did J.J. Thomson do?
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Showed experimentally the existence of the electron
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| 28 |
what are subatomic particles?
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inconceivably small atoms that contain even smaller particles. these include (neutron, electrons...
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| 29 |
Who invented one of the new instruments that was important to the development of atomic theory?
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Sir Williams Crookes
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| 30 |
What did Sir Williams Crookes invent?
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the Crookes tube
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| 31 |
what was the purpose of the Crookes tube?
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it opened the door to the subatomic structure of the atom. The emissions generated in a Crookes...
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| 32 |
what did J.J. Thomson demonstate?
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that cathode rays:1. travel in straight lines2. are negative in charge3. are deflected by electric...
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| 33 |
why was J.J. Thomsons demonstration important?
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it was the experimental discovery of a fundamental unit of charge, the electron
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| 34 |
how did television come about?
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vacuum tubes -> Crookes tube -> cathoderay tubes -> television
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| 35 |
what is an electron?
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a particle with negative electrical charge and a mass of 9.110X10-28 g.
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| 36 |
what is the assigned charge of an electron?
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-1
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| 37 |
who first discovered protons?
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Eugene Goldstein
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| 38 |
who discovered the nature of protons?
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J.J. Thomson
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| 39 |
What is a proton?
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a particle with an actual mass of 1.673x10-24 g.
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| 40 |
what is the relative charge of a proton?
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+1
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| 41 |
what did Thomson show about atoms?
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they had both negatively and positively charged particles
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| 42 |
what did Thomson's model of the atom show?
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the electrons are negatively charged particles embedded in the atomic sphere, it also contains...
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| 43 |
In Thomsons mode, how are positive ions explained?
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by assuming that the neutral atom loses electrons
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| 44 |
How are negative ions explained?
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by assuming that additional electrons can be added to the atom.
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| 45 |
who discovered the third major subatomic particle?
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James Chadwick
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| 46 |
what was the third major subatomic particle to be discovered?
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the neutron
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| 47 |
What is a neutron?
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a subatomic particle that is neither positively or negatively charged. it has an actual mass...
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| 48 |
what is the symbole for the electron?
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e-
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| 49 |
what is the symbol for the proton?
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p
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| 50 |
what is the symbol for the neutron?
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n
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| 51 |
what is the relative charge for all the subatomic particles?
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electron -> -1proton -> +1neutron -> 0
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| 52 |
who discovered radioactivity?
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Henri Bacquerel
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| 53 |
what do radioactive elements do?
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emit alpha particles, beta particles and gamma rays from their nuclei
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| 54 |
who established that the positively charged alpha particles emittted by certain radioactive...
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Ernest Rutherford
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| 55 |
what did Rutherford do?
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he used alpha particles to establish the nuclear nature of atoms
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| 56 |
what did Rutherford note?
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that light, negatively charged electrons are present and offset the positive charges in the...
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| 57 |
what is a nucleus?
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the part of an atom that contains protons and neutrons but does not contain electrons
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| 58 |
what is an atomic number?
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the number of protons in the nucleus of an atom of that element
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| 59 |
what does the atomic number determine?
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the identity of an atom, it also tells us the number of positive charges in the nucleus but...
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| 60 |
what are isotopes?
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atoms of an element having the sam eatomic number but different atomic masses
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| 61 |
how do the masses of isotopes vary?
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from the different number of protons and electrons
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| 62 |
what are the names of the three known isotopes of hydrogen?
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protium, deutrium, tritium
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| 63 |
how do you represent atoms?
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through isotopic notation
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| 64 |
what is a mass number?
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the sum of the number of protons and the number of neutrons in the nucleus
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| 65 |
how do most elements occur in nature?
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as mixtures of isoptopes
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| 66 |
what does a mass spectrometer do?
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it measures/determines the masses of individual atoms (its an instrument of measurement)
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| 67 |
what is the value of an atomic mass unit?
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equal to exactly 1/12 of the mass of a carbon-12 atom, so therefore 1 amu= 1.6606x10-24
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| 68 |
how do you calculate the average atomic mass?
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multiply the atomic mass of each isotope by the fraction of each isotope present and adding...
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| 69 |
what is atomic mass?
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the average relative mass of the isotopes of that element compared to the atomic mass of carbon-12
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| 70 |
how do you find the number of neutrons in an isotope?
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subtract the atomic number from the mass number
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| 71 |
what is electromagnetic radiation?
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one of the ways that energy travels through space.
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| 72 |
what are examples of electromagnetic radiation?
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sun, x-rays, mircrowaves, radio/television waves, radiant heat from the fireplace
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| 73 |
what are wavelengths?
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it is the distance between consecutive peaks (or troughs) in a wave
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| 74 |
what is frequency?
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how many waves pass through a particular point per second
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| 75 |
what is speed?
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tells how fast a wave moves through space
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| 76 |
what are photons?
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beams of light behaves like a stream of tiny "packets" of energy
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| 77 |
what is the name of the symbol that represents a wavelength?
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lambda
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| 78 |
what is the name of the symbol that represents a frequency?
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nu
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| 79 |
what is a line spectrum?
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when the light emitted by a gas is passed through a prism or diffraction grating, a set of...
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| 80 |
who made a significant contribution to the knowledge of the atomic structure?
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Neils Bohr
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| 81 |
What did Bohr's research lead him to believe?
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electrons exist in specific regions at various distances from the nucleus. visualized the electrons...
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| 82 |
who applied the concept of energy quanta?
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Max Planck
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| 83 |
what did Planck state?
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energy is never emitted in a continuous steam but only for small discrete packets
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| 84 |
what is quanta?
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small discrete packets of light
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| 85 |
what did Bohr state?
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theorized that electrons have several possible energies corresponding to several possible orbits...
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| 86 |
what is the ground state?
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a number of energy levels are available, the lowest of which is called the ground state
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| 87 |
what is wave mechanics/quantum mechanics?
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a new branch of physics dealing with the atom and the modern understanding for the atomic sturucture
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| 88 |
who suggestred that all objects have wave properties?
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Louis De Broglie
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| 89 |
who created a mathematical model that described electrons as waves?
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erwin schrodinger
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| 90 |
what is now possible using schrodingers wave mechanics?
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the probability of finding an electron in a certain region around the nucleus
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| 91 |
what are orbitals?
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where electrons are actually found
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| 92 |
what does principal energy levels mean?
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existing within the atom, these energy levels contain orbitals within which electrons are found
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| 93 |
what are sublevels?
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the energy levels are broken down into into sublevels
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| 94 |
what is "spin"?
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electron appears to be spinning on the axis just like a globe
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| 95 |
what is the Pauli exclusion principle?
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the rule that states that an atomic orbital can hold a maximum of two electrons which must...
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| 96 |
what is an orbital diagram?
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boxes represent the orbitals containing small arrows indicating the electrons
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| 97 |
what is electron configuration?
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shows the number of electrons in it as an exponent
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| 98 |
what are valence electrons?
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the electrons in the outermost energy level of an atom
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| 99 |
what is a period?
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each horizontal row in the periodic table
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| 100 |
how many periods are there on the periodic table?
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7
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| 101 |
what are groups/families?
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elements that behave in a similar manner are in the ssam family/group. they are the vertical...
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| 102 |
what are representative elements?
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"A" groups
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| 103 |
what are the transitional elements?
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the "B" groups
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