August 2017 Chemistry Regents #61-65

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Questions 61-65

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Base your answers to questions 61 through 65 on the information below and on your knowledge of chemistry.

Many scientists made observations of the elements that led to the modern Periodic Table. In 1829, Dobereiner found groups of three elements that have similar properties and called each of these groups a triad. Dobereiner noticed a relationship between the atomic masses of the elements in each triad. Triad 1, shown in the table below, consists of sulfur, selenium, and tellurium. The middle element, selenium, has an atomic mass that is close to the sum of the atomic masses of sulfur and tellurium, divided by 2.

For example: , which is close to the 79 u value in the table. The other triads shown in the table below demonstrate the same mathematical relationship.

61 Identify the triad that contains a metalloid. [1]

Answer-->Triad 1     or   S, Se, Te

62 Explain, in terms of electrons, why the elements in triad 2 have similar chemical properties. [1]

Answer-->same number of electrons in the valence shell.

63 State the trend in first ionization energy as the elements in triad 3 are considered in order of increasing atomic number. [1]

Answer-->As the atomic number increases, the first ionization energy decreases

64 Compare the volume of a 100.-gram sample of the first element in triad 4 to the volume of a 100.-gram sample of the third element in triad 4 when both samples are at room temperature. [1]

Answer-->The volume of the Li sample is larger

65 Show a numerical setup that demonstrates Dobereiner’s mathematical relationship for triad 2. [1]

Answer-->  (40 +137)/2

 

Next-->Questions 66-68

Questions 1-5 Questions 6-10 Questions 11-15 Questions 16-20 Questions 21-25 Questions 26-30 Questions 31-35 Questions 36-40 Questions 41-45 Questions 46-50

Questions 51-52 Questions 53-54 Questions 55-58 Questions 59-60 Questions 61-65 Questions 66-68 Questions 69-72 Questions 73-77  Questions 78-81  Questions 82-85

 

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