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- Explain why atomic radius decreases as you move to the right across a period for main-group elements but not for transition elements.
Problem 93
- Explain why vanadium (radius = 134 pm) and copper (radius = 128 pm) have nearly identical atomic radii, even though the atomic number of copper is about 25% higher than that of vanadium. Predict the relative densities of these two metals. Look up the densities in a reference book, periodic table, or on the Internet to check if your predictions are correct.
Problem 94
- The lightest noble gases, such as helium and neon, are completely inert—they do not form any chemical compounds whatsoever. In contrast, the heavier noble gases do form a limited number of compounds. Explain this difference in terms of trends in fundamental periodic properties.
Problem 95
- Why does the lightest halogen, which is also the most chemically reactive, exhibit a decrease in reactivity as you move down the column of halogens in the periodic table? Explain this trend in terms of periodic properties.
Problem 96
- Why is the electron affinity of each group 5A element more positive than that of each corresponding group 4A element? Use the outer electron configurations for these columns to suggest a reason for this observation.
Problem 98
Problem 99
The elements with atomic numbers 35 and 53 have similar chemical properties. Based on their electronic configurations, predict the atomic number of a heavier element that also should share these chemical properties.
Problem 101
You have cracked a secret code that uses elemental symbols to spell words. The code uses numbers to designate the elemental symbols. Each number is the sum of the atomic number and the highest principal quantum number of the highest occupied orbital of the element whose symbol is to be used. The message may be written forward or backward. Decode the following messages: a. 10, 12, 58, 11, 7, 44, 63, 66
Problem 103
Use Coulomb's law to calculate the ionization energy in kJ>mol of an atom composed of a proton and an electron separated by 100.00 pm. What wavelength of light has sufficient energy to ionize the atom?
Problem 104
The first ionization energy of sodium is 496 kJ/mol. Use Coulomb's law to estimate the average distance between the sodium nucleus and the 3s electron. How does this distance compare to the atomic radius of sodium? Explain the difference.
Problem 105
Consider the elements: B, C, N, O, F. d. Which element has three unpaired electrons?
Problem 106b
Consider the elements: Na, Mg, Al, Si, P. b. Which element has the smallest atomic radius?
Problem 106c
Consider the elements: Na, Mg, Al, Si, P. c. Which element is least metallic?
Problem 106d
Consider the elements: Na, Mg, Al, Si, P. d. Which element is diamagnetic?