AP Chemistry Unit 1 Quiz & Flashcards for Progress Check

Questions and Answers

Which of the following numerical expressions gives the number of moles in 5.0g of CaO?

5.0g ÷ 56 g/mol

Which of the following pieces of information is most useful for determining the number of Cu atoms in a 21g sample of pure Cu metal?

The molar mass of Cu

A 1.0mol sample of which compound has the greatest mass?

N2O5

According to the mass spectrum for an unknown element, the atomic mass is closest to what?

91 amu Signup and view all the answers

The mass spectrum represented is most consistent with which element?

Gd Signup and view all the answers

Based on the mass spectrum of a pure element, the average atomic mass of the element is closest to what?

186.3 amu Signup and view all the answers

What scientific question can best be answered based on the experiment with BaCl2?

Is the BaCl2 used in the experiment pure? Signup and view all the answers

What can be calculated from heating a mass of metallic element M to form MO?

What is the molar mass of M? Signup and view all the answers

What is the empirical formula of a compound containing 36.0g of C and 6.0g of H?

The empirical formula of the compound Signup and view all the answers

What information is helpful in determining whether a powder labeled NaCl is pure?

Mass percent of Na Signup and view all the answers

What additional information is needed to calculate the mole percent of XCl and ZCl in a mixture?

The molar masses of X and Z Signup and view all the answers

What is needed to determine the mole fraction of each gas in a gas mixture?

The molar mass of each gas Signup and view all the answers

How many unpaired electrons are in the atom represented by the electron configuration 1s22s22p63s23p6?

0 Signup and view all the answers

Which of the following represents the electron configuration of an oxygen atom in the ground state?

(C) Signup and view all the answers

What is the correct electron configuration for a ground-state atom of magnesium?

1s2 2s2 2p6 3s2 Signup and view all the answers

Which labeled peak corresponds to the 1s electrons in the photoelectron spectrum and why?

Peak XX, because 1s electrons have the strongest attractions to the nucleus Signup and view all the answers

How is the photoelectron spectrum for boron consistent with the electron shell model?

The spectrum shows a single electron in the 2p subshell. Signup and view all the answers

How is the photoelectron spectrum for carbon consistent with the electron shell model?

The spectrum shows equal numbers of electrons in the three occupied electron subshells. Signup and view all the answers

What helps explain the trend of increasing atomic radius from N to Bi?

The attractive force between the valence electrons and nuclei decreases. Signup and view all the answers

What explains 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. Signup and view all the answers

What 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 that of Ca. Signup and view all the answers

Why does an atom of Rb gas more easily lose 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. Signup and view all the answers

Which element reacts 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. Signup and view all the answers

What charge does Al typically have in ionic compounds, and why?

+3, because it has three valence electrons. Signup and view all the answers

Study Notes

Moles and Mass Calculations

Number of moles calculated using mass of sample divided by molar mass (e.g., 5.0g of CaO ÷ 56 g/mol).
For 21g of copper (Cu), molar mass is essential to find the number of Cu atoms via Avogadro's number.
The compound with the highest molar mass in a sample of 1.0 mol is N2O5 due to the number of atoms in the molecules.

Atomic Mass and Isotopes

Average atomic mass from isotopes can be estimated; for unknown elements around 91 amu based on relative abundances.
Gadolinium (Gd) isotopes suggest an average atomic mass of around 157 amu based on spectrum data.
A pure element's average atomic mass can be derived from its isotopes, yielding 186.3 amu in a specific example.

Experimental Procedures and Purity

The purity of BaCl2 can be assessed by comparing moles of Ba in the precipitate with moles in the sample.
The molar mass of unknown metallic element M can be determined by mass change before and after reaction with oxygen.
Empirical formulas derived from ratios of moles of C and H can identify substances.

Analytical Techniques

Mass percent composition aids in determining purity of NaCl, an intensive property.
Molar masses of components X and Z in a chloride mixture are necessary to calculate mole percent.
For gas mixtures, molar masses are crucial to find each gas's mole fraction.

Electron Configuration and Spectra

Atom with electron configuration 1s² 2s² 2p⁶ 3s² 3p⁶ has zero unpaired electrons.
The correct ground-state electron configuration of oxygen reflects eight total electrons.
Magnesium, with atomic number 12, has a specific electron configuration sequence.

Photoelectron Spectra Insights

The peak corresponding to 1s electrons is identified based on binding energy; it indicates strong nuclear attraction.
Boron's photoelectron spectrum illustrates electron subshell occupancy matching its configuration.
Carbon's spectrum demonstrates equal numbers of electrons across occupied subshells, consistent with its structure.

Atomic Radii Trends

Increasing atomic radius in the nitrogen group explained by decreasing effective nuclear charge as elements descend the group.
Potassium (K) has a greater atomic radius than bromine (Br) due to lower effective nuclear charge on valence electrons in K.

Ionization Energy and Atomic Behavior

First ionization energy of K is lower than Ca due to less effective nuclear charge affecting electron attraction.
Rubidium (Rb) loses electrons more easily than lithium (Li) because Rb's valence electron is further from its nucleus.
Elements in the same periodic group, like Cs and Rb, react with oxygen in a fixed mole ratio due to similar valence electron configurations.

Ionic Charges and Reactions

Aluminum typically has a +3 charge in ionic compounds due to its three valence electrons being easily removed.

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Description

Test your knowledge with this progress check quiz designed for AP Chemistry Unit 1. Answer multiple-choice questions and flashcards focused on moles, mass, and atomic calculation. This interactive quiz will help reinforce your understanding of key concepts in chemistry.

AP Chemistry - Unit 1 Progress Check