Chapter7 - CHE141 Chapter 7 Chapter 7 Periodic Properties...

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CHE141 Chapter 7 Copyright © 2006 Dr. Harshavardhan D. Bapat 1 Chapter 7 Periodic Properties of the Elements 1. Elements in the modern version of the periodic table are arranged in order of increasing __________. (a). oxidation number (b). atomic mass (c). average atomic mass (d). atomic number Explanation: The older version of the periodic table had the elements arranged in order of increasing atomic mass, but the modern version of the periodic table is based on the increasing order of atomic number. 2. The first ionization energies of the elements __________ as you go from left to right across a period of the periodic table, and __________ as you go from the bottom to the top of a group in the table. (a). increase, increase (b). increase, decrease (c). decrease, increase (d). decrease, decrease Explanation: The ionization energies (IE s) of elements increase to the right in a row since larger amounts of energy need to be supplied to remove an electron. The elements become more non-metallic making it harder to remove an electron. 3. The __________ have the most negative electron affinities (a). alkaline earth metals (b). alkali metals (c). halogens (d). transition metals Explanation: The electron affinity of an element is defined as the energy change that occurs when an electron is added to a gaseous atom. The halogens have the most negative electron affinities indicating that they are most comfortable accepting an electron. The formation of an anion essentially gives the halogen atom the electron configuration of the nearest noble gas. The negative sign here indicates that the addition of an electron to the halogens results in energy being released by the halogen atom.
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CHE141 Chapter 7 Copyright © 2006 Dr. Harshavardhan D. Bapat 2 4. Element M reacts with chlorine to form a compound with the formula MCl 2 . Element M is more reactive than magnesium and has a smaller radius than barium. This element is __________. (a). Sr (b). K (c). Na (d). Ra Explanation: The formula of the compound MCl 2 indicates that M must have 2+ charges on it and it must be an alkaline-earth metal. Element reactivity and atomic radius typically increase down the group, which means that the element could be Ca or Sr. Since Sr is the only option that fits the answer is Sr. 5. The oxide of which element below can react with hydrochloric acid? (a). sulfur (b). selenium (c). sodium (d). nitrogen Explanation: For the oxide to react with hydrochloric acid, it must be a basic oxide. Only metals form basic oxides and out of the options provided, sodium is the only metal. 6. Metals can be __________ at room temperature. (a). liquid only (b). solid only (c). solid or liquid (d). solid, liquid, or gas Explanation: Most metals are solids at room temperature with one prominent exception, which is mercury. 7.
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Chapter7 - CHE141 Chapter 7 Chapter 7 Periodic Properties...

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