Q: What is the charge-to-mass ratio of the electron as measured by J.J. Thomson?

$$-1.76 \times 10^8$ \ \mathrm{C/g}$$

Q: The atomic mass of chlorine is 35.45 amu. Given that $$^{35}\mathrm{Cl}$$ has a mass of 34.97 amu and an abundance of 75.77%, and $$^{37}\mathrm{Cl}$$ has a mass of 36.97 amu and an abundance of 24.23%, which formula correctly calculates the atomic mass?

$$(34.97 \times 0.7577) + (36.97 \times 0.2423)$$

Q: How many atoms are present in 2.45 moles of copper?

$$2.45 \times 6.022 \times 10$$^{23}$$ = 1.48 \times 10$$^{24}$$ atoms

Q: A sample contains 0.571 g of Q per 1 g of A in AQ. What is the mass ratio of Q to A in $$A_2Q_3$$?

$$0.571 \times \frac{3}{2} = 0.857$$

Question 1

Which experimental technique allows scientists to image and manipulate individual atoms on a surface, as shown in the provided images?

Accepted Answer

Scanning tunneling microscopy (STM)

Question 2

Which law states that in a chemical reaction, matter is neither created nor destroyed?

Accepted Answer

Law of Conservation of Mass

Question 3

A sample of carbon monoxide contains 1.33 g of oxygen per 1 g of carbon, while carbon dioxide contains 2.67 g of oxygen per 1 g of carbon. What law does this observation illustrate?

Accepted Answer

Law of Multiple Proportions

Question 4

Which scientist is credited with the discovery of the electron using cathode ray tubes?

Accepted Answer

J.J. Thomson

Question 5

What is the charge-to-mass ratio of the electron as measured by J.J. Thomson?

Accepted Answer

$$-1.76 	imes 10^8$ \ \mathrm{C/g}$$

Question 6

Which experiment led to the discovery of the atomic nucleus?

Accepted Answer

Rutherford gold foil experiment

Question 7

Which of the following statements is NOT part of Dalton’s Atomic Theory?

Accepted Answer

Atoms of one element can change into atoms of another element during chemical reactions.

Question 8

A neutral atom of chlorine has 17 protons and 18 neutrons. What is its mass number and chemical symbol in isotope notation?

Accepted Answer

$$^{35}_{17}\mathrm{Cl}$$

Question 9

The atomic mass of chlorine is 35.45 amu. Given that $$^{35}\mathrm{Cl}$$ has a mass of 34.97 amu and an abundance of 75.77%, and $$^{37}\mathrm{Cl}$$ has a mass of 36.97 amu and an abundance of 24.23%, which formula correctly calculates the atomic mass?

Accepted Answer

$$(34.97 	imes 0.7577) + (36.97 	imes 0.2423)$$

Question 10

How many atoms are present in 2.45 moles of copper?

Accepted Answer

$$2.45 	imes 6.022 	imes 10$$^{23}$$ = 1.48 	imes 10$$^{24}$$ atoms

Question 11

Which of the following best explains why the atomic mass of most elements is not a whole number?

Accepted Answer

Because atomic mass is a weighted average of all naturally occurring isotopes.

Question 12

Which group of elements on the periodic table is most likely to form cations with a +1 charge?

Accepted Answer

Alkali metals (Group 1)

Question 13

A sample contains 0.571 g of Q per 1 g of A in AQ. What is the mass ratio of Q to A in $$A_2Q_3$$?

Accepted Answer

$$0.571 	imes \frac{3}{2} = 0.857$$

Question 14

Which of the following is a property of metals as shown in the periodic table diagrams?

Accepted Answer

They are good conductors of heat and electricity.

Question 15

Which of the following best describes the difference between the plum-pudding model and the nuclear model of the atom?

Accepted Answer

The plum-pudding model has electrons embedded in a sphere of positive charge, while the nuclear model has a dense nucleus with electrons in a cloud around it.

Question 16

Which of the following is the correct relationship for converting grams of an element to number of atoms?

Accepted Answer

$$	ext{grams} 	o 	ext{moles} 	o 	ext{number of atoms}$$

Question 17

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes of an element have the same number of protons but different numbers of neutrons.

Question 18

A mass spectrometer separates ions based on which property?

Accepted Answer

Mass-to-charge ratio ($$m/z)$$

Question 19

Which of the following best describes Avogadro’s number?

Accepted Answer

The number of atoms in exactly 12 grams of carbon-12

Atoms and Elements: Foundations of Modern Atomic Theory

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