rising to 1.5/1 for elements having atomic numbers between 20 and 83. An understanding of the Belt of Stability will allow you to predict how unstable nuclides will decay. The typical modes of radioactive decay are alpha decay‚ beta decay and electron capture (or positron emission). During alpha decay‚ the mass number of the nuclide decreases by 4 units and the number of protons decreases by 2. This type of decay is associated with heavy‚ unstable nuclides. Since no stable isotopes exist
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– PHYSICIST WHO DISCOVERED ELECTRONS (e-) * The cathode ray * “plum pudding model” aka Chocolate Chip Cookie or Blueberry Muffin Model of an atom with electrons * Ernest “radioactive man” Rutherford (1907) – “gold foil experiment” * Electron cloud theory * Discovered that the nucleus has a positive charge * Most of the atom is empty space * Neils Bohr – planetary model (2D) worked with hydrogen * Worked with Rutherford * Electrons have specific orbitals where
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the problems with Dalton’s theory are that his second law that all atoms of the same element are the same is false because today we have found that there are other kinds of atoms called isotopes. An isotope is an atom that has the same amount of electrons and protons‚ but it has more neutrons that increase its atomic mass. Some examples of isotopes are Carbon 12‚ carbon 13‚ carbon 14‚ Uranium (234‚ 235‚ and 238) and lithium (6‚ 7). Carbon 14 is especially useful because we know its rate of decay and
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surface of a metal. If only 1 of each 5 × 109 incident photons is absorbed and causes an electron to be ejected from the surface‚ the total photocurrent in the circuit is ________. 3. Light of wavelength 330 nm falling on a piece of metal ejects electrons with sufficient energy which requires voltage V0 to prevent a electron from reading collector. In the same setup‚ light of wavelength 220 nm‚ ejects electrons which require twice the voltage V0 to stop them in reaching a collector. Find the numerical
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tire pressures are off. The first thing that I would like to do is explain what electricity is in an automobile. Electricity is the worlds most widely used source if energy. Electricity is the flow of electrons through a conductor to eventually be used to supply a load of some sort. The electrons flow from positive to negative. In order to understand how an electric charge moves from one atom to another‚ you need to learn a little about atoms. Everything that surrounds us is made of atoms; every
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electric charge in several ways. These include the quantities Current‚ Voltage and Power. Current * Current (I) is the rate of flow of Charge Carriers‚ such as electrons. Current is usually thought of as moving in the direction of positive charge‚ so from the positive power supply to the negative. However‚ since in metals it is electrons that carry electric charge‚ the actually flow is opposite to the way in which we think of it. * Current it the amount of Charge‚ Q that passes a point in
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particles. The constituent particles of an atom are the electron‚ the proton and the neutron. However‚ the hydrogen-1 atom has no neutrons and a positive hydrogen ion has no electrons. The electron is by far the least massive of these particles at 9.11×10−31 kg‚ with a negative electrical charge and a size that is too small to be measured using available techniques.[46] Protons have a positive charge and a mass 1‚836 times that of the electron‚ at 1.6726×10−27 kg‚ although this can be reduced by
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discovered the electron. In Thomson’s "Plum Pudding Model" each atom was a sphere filled with a positively charged fluid. The fluid was called the "pudding." Scattered in this fluid were electrons known as the "plums." The radius of the model was 10-10 meters. Thomson suggested that the positive fluid held the negative charges‚ the electrons‚ in the atom because of electrical forces. Thomson’s “Plum Pudding Model is used in science‚ because it was the first model utilising electrons. He and his fellow
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SLG Practice Final Exam Chem. 113 True and False 1. The Bohr Theory explains that an emission spectral line is due to an electron losing energy and changing orbitals. 2. 4s orbitals have higher energy than 3d orbitals. 3. An atom with an even number of electrons is always diamagnetic. 4. Covalent bonds are formed by atoms sharing electrons. Multiple Choice 5. Choose the INCORRECT statement about NH2-: a) There is one lone pair on N. b) There are two σ bonds. c) There are no π
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Shapes‚ Valance Bond Theory‚ and Molecular Orbital Theory 1) Determine the electron geometry (eg) and molecular geometry(mg) of BCl3. A) eg=trigonal planar‚ mg=trigonal planar B) eg=tetrahedral‚ mg=trigonal planar C) eg=tetrahedral‚ mg=trigonal pyramidal D) eg=trigonal planar‚ mg=bent E) eg=trigonal bipyramidal‚ mg= trigonal bipyramidal Answer: A 2) Determine the electron geometry (eg)‚ molecular geometry (mg)‚ and polarity of SO2. A) eg=tetrahedral
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