- May 2020
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chem.libretexts.org chem.libretexts.org
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An alpha particle is composed of 2 protons and 2 neutrons. It has a charge of 2. The original atoms atomic number decreases by 2 and the mass decreases by 4.
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Gamma rays knock out electrons out of atoms and give them a charge.
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A beta particle is an electron (former atom in the nucleus) kicked out of the nucleus. It contains a charge of -1.
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Alpha particles, beta particles, and gamma rays are the key types of radioactivity.
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chem.libretexts.org chem.libretexts.org
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A battery in the circuit creates a voltage between the plates. Next to the plates is a small disk containing a tiny amount (∼0.0002 g) of the radioactive element americium (Am). The radioactivity of the americium ionizes the air between the plates, causing a tiny current to constantly flow between them.
The battery in the circuit makes a voltage between the metal plates and near the small disk containing a tiny amount of the radioactive element americium. The radioactivity of the americium ionizes the air between the plates. This causes a tiny current to flow consistantly between them.
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Smoke detectors depend on radioactivity.
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chem.libretexts.org chem.libretexts.org
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ms=+1/2
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Electrons enter higher-energy subshells only after low-energy subshells have been filled to capacity.
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Electron configuration: The # of the principal quantum shell,n; the letter that designates the orbital type; a superscript # that designates the number of the electrons in the particular sub shell.
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energy of atomic orbitals increases as the principal quantum number, n, increases.
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- Apr 2020
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chem.libretexts.org chem.libretexts.org
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Rewrite the following list in order of decreasing electron affinity: fluorine (F), phosphorous (P), sulfur (S), boron (B).
F, S, P, B
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Why is the electronegativity value of most noble gases zero?
Noble gases already have a full valence electron shell so they do not need to lose or gain valance electrons.
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Arrange these atoms in order of decreasing effective nuclear charge by the valence electrons: Si, Al, Mg, S
Si, S, Al, Mg
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Periodic trends are specific patterns that are present in the periodic table that illustrate different aspects of a certain element, including its size and its electronic properties. Major periodic trends include: electronegativity, ionization energy, electron affinity, atomic radius, melting point, and metallic character. Periodic trends, arising from the arrangement of the periodic table, provide chemists with an invaluable tool to quickly predict an element's properties. These trends exist because of the similar atomic structure of the elements within their respective group families or periods, and because of the periodic nature of the elements.
A periodic table contains patterns that occur in elements, giving us the electronegativity, ionization energy, electron affinity, atomic radius, etc.
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