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Unformatted text preview: shah (rps587) Homework 1 mcdevitt (52365) 1 This print-out should have 20 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 10.0 points Which of the following elements would be expected to resemble silicon (Si) most closely in chemical properties? 1. bromine (Br) 2. sulfur (S) 3. germanium (Ge) correct 4. aluminum (Al) 5. arsenic (As) Explanation: Elements with similar chemical properties are arranged in the same group or vertical column. Thus Germanium (Ge) would be expected to have similar properties to silicon (Si). 002 10.0 points Which of the following has the smallest atomic radius? 1. P 2. Si 3. Al 4. Cl correct 5. S Explanation: As you move down the periodic table atomic radius increases because the shielding effects of inner electrons reduces the effective nuclear charge experienced by outer shell elec- trons. As you move across the periodic table the radius decreases because electrons are be- ing added to the same electronic shell (and thus do not add additional shielding effects) while the number of protons increases. 003 10.0 points Which of the following statements is true? 1. Atoms with high ionization energies and high electron affinities are highly electronega- tive. correct 2. The electronegativity of an atom depends only on the value of the ionization energy of the atom. 3. Atoms with low ionization energies and low electron affinities have high electronega- tivities. 4. The electronegativity of an atom is de- fined as 1 2 (Electron Affinity) of the atom. 5. Atoms with high ionization energies and high electron affinities have low electronega- tivities. Explanation: Atoms with high ionization energies do not readily give up electrons to form positive ions. For these atoms it is usually favorable to gain electrons to form negative ions, so electron affinities and electronegativities tend to be large. In Mullikens scale, electronegativity = 1 2 (First Ionization Energy + Electron Affin- ity). 004 10.0 points Which of the following has the largest radius? 1. Cl 2. S 2- correct 3. K + 4. S 5. Cl- Explanation: Although size decreases from left to right shah (rps587) Homework 1 mcdevitt (52365) 2 across the periodic table due to increasing effective nuclear charge, the negative ions will be the largest ions, and the negative ion with the largest charge will have the largest radius since the electrons will repel each other and the effective nuclear charge will be insufficient to overcome this repulsion....
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- Spring '09