Unit 1 progress check
Which of the following best helps explain why an atom of Rb gas more easily loses an electron in a chemical reaction than an atom of Li gas?
In the Rb atom the valence electron is farther from its nucleus than the valence electron of Li is from its nucleus
Which of the following best helps explain why the first ionization energy of K is less than that of Ca?
The valence electron of K experiences a lower effective nuclear charge than the valence electrons of Ca.
What charge does Al typically have in ionic compounds, and why?
+3, because it has three valence electrons.
Rb reacts with O in a mole ratio of 2 to 1, forming the ionic compound Rb2O. Which of the following elements will react with O in a mole ratio of 2 to 1, forming an ionic compound, and why?
Cs, because it is in the same group as Rb.
A student obtains a 10.0g10.0g sample of a white powder labeled as BaCl2BaCl2. After completely dissolving the powder in 50.0mL50.0mL of distilled water, the student adds excess Na2SO4(s)Na2SO4(s), which causes a precipitate of BaSO4(s)BaSO4(s) to form, as represented by the equation above. The student filters the BaSO4(s)BaSO4(s), rinses it, and dries it until its mass is constant. Which of the following scientific questions could best be answered based on the results of the experiment?
Is the BaCl2(s)BaCl2(s) used in the experiment pure?
In terms of atomic structure, explain why the atomic radius of K is larger than that of Na.
K has another electron shell making the valence electrons further from the nucleus.
A jar labeled NaClNaCl contains a powder. The table above contains information determined by analyzing a sample of the powder in the laboratory. What information in the table is the most helpful in determining whether the powder is pure NaClNaCl?
Mass percent of Na
The atomic radii of the elements in the nitrogen group in the periodic table are given in the table above. Which of the following best helps explain the trend of increasing atomic radius from N to Bi?
The attractive force between the valence electrons and the nuclei of the atoms decreases.
Which of the following best helps to explain why the atomic radius of K is greater than that of Br?
The effective nuclear charge experienced by valence electrons is smaller for K than for Br.
In a lab a student is given a 21g21g sample of pure CuCu metal. Which of the following pieces of information is most useful for determining the number of CuCu atoms in the sample? Assume that the pressure and temperature in the lab are 1.0atm1.0atm and 25°C25°C.
The molar mass of Cu
A vessel contains a mixture of gases. The mass of each gas used to make the mixture is known. Which of the following information is needed to determine the mole fraction of each gas in the mixture?
The molar mass of each gas
A student obtains a mixture of the chlorides of two unknown metals, XX and ZZ. The percent by mass of XX and the percent by mass of ZZ in the mixture is known. Which of the following additional information is most helpful in calculating the mole percent of XCl(s)XCl(s) and of ZCl(s)ZCl(s) in the mixture?
The molar masses of X and Z
A student measures the mass of a sample of a metallic element, MM. Then the student heats the sample in air, where it completely reacts to form the compound MOMO. The student measures the mass of the compound that was formed. Which of the following questions can be answered from the results of the experiment?
What is the molar mass of M?