Q: Which equation represents the charge-to-mass ratio of the electron as determined by J.J. Thomson?

$$\frac{e}{m} = 1.76 \times 10^8$ \ \mathrm{C/g}$$

Q: Millikan’s oil drop experiment determined the charge of the electron. If the charge measured was $$-1.6 \times 10$$^{-19}$$ \ \mathrm{C}$$, what is the mass of the electron using Thomson’s charge/mass ratio?

$$9.1 \times 10$$^{-28}$$ \ \mathrm{g}$$

Q: A sample contains 24.0 g of magnesium (Mg). How many atoms of magnesium are present in the sample? (Molar mass of Mg = 24.3 g/mol, Avogadro’s number $$= 6.022 \times 10$$^{23}$$ atoms/mol)

$$5.95 \times 10$$^{23}$$ atoms

Question 1

Which experiment provided direct evidence for the existence of atoms by observing the random motion of particles suspended in a fluid?

Accepted Answer

Brownian motion experiments by Einstein and Perrin

Question 2

According to Dalton’s atomic theory, which statement is correct?

Accepted Answer

Atoms of different elements combine in simple whole-number ratios to form compounds

Question 3

In the cathode ray tube experiment, what was the significance of the observed deflection of the beam in electric and magnetic fields?

Accepted Answer

It demonstrated that cathode rays were negatively charged particles (electrons)

Question 4

Which equation represents the charge-to-mass ratio of the electron as determined by J.J. Thomson?

Accepted Answer

$$\frac{e}{m} = 1.76 	imes 10^8$ \ \mathrm{C/g}$$

Question 5

Millikan’s oil drop experiment determined the charge of the electron. If the charge measured was $$-1.6 	imes 10$$^{-19}$$ \ \mathrm{C}$$, what is the mass of the electron using Thomson’s charge/mass ratio?

Accepted Answer

$$9.1 	imes 10$$^{-28}$$ \ \mathrm{g}$$

Question 6

Rutherford’s gold foil experiment led to which major revision of the atomic model?

Accepted Answer

Atoms have a small, dense nucleus containing protons and neutrons, with electrons occupying most of the volume

Question 7

Which statement best describes the difference between isotopes of the same element?

Accepted Answer

They have different numbers of neutrons

Question 8

A sample contains 24.0 g of magnesium (Mg). How many atoms of magnesium are present in the sample? (Molar mass of Mg = 24.3 g/mol, Avogadro’s number $$= 6.022 	imes 10$$^{23}$$ atoms/mol)

Accepted Answer

$$5.95 	imes 10$$^{23}$$ atoms

Question 9

Which of the following elements is a metalloid and commonly used as a semiconductor in electronics?

Accepted Answer

Silicon

Question 10

Which group in the periodic table contains elements that are mostly unreactive and exist as gases at room temperature?

Accepted Answer

Noble gases

Question 11

A main-group metal tends to lose electrons to form a cation. What is the resulting electron configuration similar to?

Accepted Answer

The nearest noble gas

Question 12

Calculate the average atomic mass of neon given the following isotopic abundances and masses: $$^{20}\mathrm{Ne} (90.48$$%, 19.992 amu), $$^{21}\mathrm{Ne} (0.27$$%, 20.994 amu), $$^{22}\mathrm{Ne} (9.25$$%, 21.991 amu).

Accepted Answer

$$20.18$$ amu

Question 13

Which property is NOT characteristic of metals?

Accepted Answer

Gain electrons during chemical changes

Question 14

Which of the following statements about the periodic table is correct?

Accepted Answer

Groups are vertical columns and periods are horizontal rows

Question 15

A sample contains $$3.00 	imes 10$$^{24}$$ atoms of carbon. What is the mass of the sample? (Molar mass of C = 12.01 g/mol, Avogadro’s number = 6.022$$ 	imes $$10^{23}$$ atoms/mol)

Accepted Answer

$$59.9 g$$

Question 16

Which element is a halogen and exists as a red-brown liquid at room temperature?

Accepted Answer

Bromine

Question 17

Which of the following best explains why most of the mass of an atom is concentrated in the nucleus?

Accepted Answer

The nucleus contains protons and neutrons, which are much more massive than electrons

Question 18

Which of the following is the correct conceptual plan for calculating the number of atoms in a sample given its mass?

Accepted Answer

$$	ext{mass} ightarrow 	ext{moles} ightarrow 	ext{number of atoms}$$

Question 19

Which of the following elements is a nonmetal and a gas at room temperature?

Accepted Answer

Oxygen

Atoms and Elements: Foundations of Atomic Theory and the Periodic Table

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