Q: A sample contains 3.00 g of carbon-12. How many atoms are present in the sample? ($$1\ \mathrm{mol} = 6.022 \times 10$$^{23}$$ atoms, $$\mathrm{Molar\ mass\ of\ C} = 12.00\ \mathrm{g/mol}$$)

$$1.51 \times 10$$^{23}$$ atoms

Q: Calculate the wavelength of light emitted when an electron in a hydrogen atom falls from $$n=3 to$$ $$n=2. $$Use the Balmer-Rydberg equation: $$\frac{1}{\lambda} = R \left( \frac{1}{n_1$^2} - \frac{1}{n_2$^2} \right)$$, where $$R = 1.097 \times 10^7$\ \mathrm{m}^{-1}.$$

$$6.56 \times 10$$^{-7}$$\ \mathrm{m}$$

Q: A patient receives 250 mg of a medication. If the molar mass of the drug is $$500\ \mathrm{g/mol}$$, how many moles of the drug did the patient receive?

$$5.0 \times 10$$^{-4}$$\ \mathrm{mol}$$

Question 1

Which of the following is an example of an extensive property?

Accepted Answer

Mass

Question 2

A student measures the mass of a sample as 12.30 g and its volume as 4.0 mL. What is the density of the sample, reported to the correct number of significant digits?

Accepted Answer

$$3.1\ \mathrm{g/mL}$$

Question 3

Which of the following statements best describes the law of definite proportions?

Accepted Answer

A chemical compound always contains exactly the same proportion of elements by mass.

Question 4

Which experiment led to the discovery of the nucleus in the atom?

Accepted Answer

Rutherford gold foil experiment

Question 5

An isotope of chlorine is represented as $$\mathrm{^{37}_{17}Cl}. $$How many neutrons does this isotope have?

Accepted Answer

20

Question 6

A sample contains 3.00 g of carbon-12. How many atoms are present in the sample? ($$1\ \mathrm{mol} = 6.022 	imes 10$$^{23}$$ atoms, $$\mathrm{Molar\ mass\ of\ C} = 12.00\ \mathrm{g/mol}$$)

Accepted Answer

$$1.51 	imes 10$$^{23}$$ atoms

Question 7

Which of the following correctly ranks the regions of electromagnetic radiation from lowest to highest frequency?

Accepted Answer

Radio waves \u003c Infrared \u003c Visible \u003c Ultraviolet \u003c Gamma rays

Question 8

According to the Bohr model, what causes the emission lines in the hydrogen spectrum?

Accepted Answer

Electrons falling from higher to lower energy levels, emitting photons

Question 9

Calculate the wavelength of light emitted when an electron in a hydrogen atom falls from $$n=3 to$$ $$n=2. $$Use the Balmer-Rydberg equation: $$\frac{1}{\lambda} = R \left( \frac{1}{n_1$^2} - \frac{1}{n_2$^2} ight)$$, where $$R = 1.097 	imes 10^7$\ \mathrm{m}^{-1}.$$

Accepted Answer

$$6.56 	imes 10$$^{-7}$$\ \mathrm{m}$$

Question 10

Which set of quantum numbers is not allowed for an electron in an atom?

Accepted Answer

$$n=2,\ l=2,\ m_l=0,\ m_s=+\frac{1}{2}$$

Question 11

Which of the following electron configurations represents a paramagnetic atom?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^3$$

Question 12

Which element has the highest first ionization energy?

Accepted Answer

Neon ($$\mathrm{Ne})$$

Question 13

Which of the following ions is isoelectronic with argon ($$\mathrm{Ar}$$)?

Accepted Answer

$$\mathrm{K^+}$$

Question 14

Which of the following elements is most likely to form a $$2^+$$ cation?

Accepted Answer

Magnesium ($$\mathrm{Mg})$$

Question 15

Arrange the following atoms in order of increasing atomic radius: $$\mathrm{Na}$$, $$\mathrm{Al}$$, $$\mathrm{P}.$$

Accepted Answer

$$\mathrm{P} \u003c \mathrm{Al} \u003c \mathrm{Na}$$

Question 16

Which of the following best explains the trend in effective nuclear charge ($$Z_{\mathrm{eff}}) $$across a period?

Accepted Answer

$$Z_{\mathrm{eff}}$$ increases because the number of protons increases while shielding remains relatively constant.

Question 17

Which of the following elements has the greatest electron affinity?

Accepted Answer

Fluorine ($$\mathrm{F})$$

Question 18

A patient receives 250 mg of a medication. If the molar mass of the drug is $$500\ \mathrm{g/mol}$$, how many moles of the drug did the patient receive?

Accepted Answer

$$5.0 	imes 10$$^{-4}$$\ \mathrm{mol}$$

Question 19

Which of the following electron configurations represents the ground state of a $$\mathrm{Fe$$^{2+}$$}$$ ion?

Accepted Answer

$$[\mathrm{Ar}]\ 3d^6$

Question 20

Which of the following best describes Hund’s Rule?

Accepted Answer

Electrons fill degenerate orbitals singly before pairing.

CHEM 1411 Study Guide: Chapters E–3 (Units, Atoms, Quantum Model, Periodic Properties)

Study Guide - Practice Questions

Study Guide - Flashcards