Problem 22
Verify that the atomic weight of magnesium is 24.31, given the following information: \(^{24} \mathrm{Mg},\) mass \(=23.985042 \mathrm{u} ;\) percent abundance \(=78.99 \%\) \(^{25} \mathrm{Mg},\) mass \(=24.985837 \mathrm{u} ;\) percent abundance \(=10.00 \%\) \(^{26} \mathrm{Mg},\) mass \(=25.982593 \mathrm{u} ;\) percent abundance \(=11.01 \%\)
Problem 25
Titanium and thallium have symbols that are easily confused with each other. Give the symbol, atomic number, atomic weight, and group and period number of each element. Are they metals, metalloids, or nonmetals?
Problem 27
How many periods of the periodic table have 8 elements, how many have 18 elements, and how many have 32 elements?
Problem 28
How many elements occur in the seventh period? What is the name given to the majority of these elements, and what well-known property characterizes them?
Problem 29
Select answers to the questions listed below from the following list of elements whose symbols start with the letter \(\mathrm{C}: \mathrm{C}, \mathrm{Ca}, \mathrm{Cr}, \mathrm{Co}, \mathrm{Cd}, \mathrm{Cl}, \mathrm{Cs}, \mathrm{Ce}\) \(\mathrm{Cm}, \mathrm{Cu},\) and Cf. (You should expect to use some symbols more than once.) (a) Which are nonmetals? (b) Which are main group elements? (c) Which are lanthanides? (d) Which are transition elements? (e) Which are actinides? (f) Which are gases?
Problem 30
Give the name and chemical symbol for the following. (a) a nonmetal in the second period (b) an alkali metal in the fifth period (c) the third-period halogen (d) an element that is a gas at \(20^{\circ} \mathrm{C}\) and 1 atmosphere pressure
Problem 31
Classify the following elements as metals, metalloids, or nonmetals: \(\mathrm{N}, \mathrm{Na}, \mathrm{Ni}, \mathrm{Ne},\) and \(\mathrm{Np}.\)
Problem 32
Here are symbols for five of the seven elements whose names begin with the letter \(\mathrm{B}: \mathrm{B}, \mathrm{Ba}, \mathrm{Bk}, \mathrm{Bi}\) and Br. Match each symbol with one of the descriptions below. (a) a radioactive element (b) a liquid at room temperature (c) a metalloid (d) an alkaline earth element (e) a group 5 A element
Problem 35
What is the charge on the common monatomic ions of the following elements? (a) magnesium (b) zinc (c) nickel (d) gallium
Problem 36
What is the charge on the common monatomic ions of the following elements? (a) selenium (b) fluorine (c) iron (d) nitrogen
