Question 1

Which statement best describes the main insight from Dalton's atomic theory?

Accepted Answer

Atoms of a given element have the same mass and properties that distinguish them from atoms of other elements.

Question 2

Which experiment led to the discovery that atoms have a small, dense nucleus?

Accepted Answer

Rutherford's gold foil experiment

Question 3

A neutral atom of sodium has 11 protons. How many electrons does it have?

Accepted Answer

$$11$$

Question 4

Which of the following best explains why metals are good conductors of electricity?

Accepted Answer

Metals have loosely held valence electrons that can move freely.

Question 5

Which element is defined by having 17 protons in its nucleus?

Accepted Answer

Chlorine

Question 6

A fluorine atom gains one electron to form an ion. What is the charge of the resulting ion?

Accepted Answer

$$-1$$

Question 7

Which of the following is a property of metalloids that makes them useful in electronics?

Accepted Answer

They have intermediate electrical conductivity that can be controlled.

Question 8

Which group in the periodic table contains the noble gases?

Accepted Answer

Group 8A

Question 9

An isotope of neon is represented as $$\displaystyle \frac{22}{10}Ne. $$How many neutrons does this isotope have?

Accepted Answer

$$12$$

Question 10

Which of the following best describes the difference between cations and anions?

Accepted Answer

Cations are positively charged, anions are negatively charged.

Question 11

A sample of chlorine contains 75.77% $$^{35}Cl ($$mass $$34.97$$ amu) and 24.23% $$^{37}Cl ($$mass $$36.97$$ amu). What is the atomic mass of chlorine? (Round to two decimal places.)

Accepted Answer

$$35.45$$ amu

Question 12

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 13

Which of the following elements is a good example of a metalloid?

Accepted Answer

Silicon

Question 14

A magnesium ion has 12 protons and 10 electrons. What is its charge?

Accepted Answer

$$+2$$

Question 15

Which of the following best explains why the atomic mass of an element is not a whole number?

Accepted Answer

It is the weighted average of the masses of all naturally occurring isotopes.

Question 16

Which of the following is a real-world application of a radioactive isotope?

Accepted Answer

Using technetium-99 to diagnose disease in patients.

Question 17

Which of the following statements about the distribution of mass in the atom is correct?

Accepted Answer

Most of the atom's mass is in the nucleus.

Question 18

If an atom has 15 protons, 16 neutrons, and 18 electrons, what is its symbol and charge?

Accepted Answer

$$^{31}_{15}P$$^{3-}$$

Question 19

Which of the following best describes the periodic law as proposed by Mendeleev?

Accepted Answer

When elements are arranged in order of increasing atomic mass, certain sets of properties recur periodically.

Question 20

Which of the following elements is most likely to form a $$+1$$ ion?

Accepted Answer

Potassium (K)

Atoms and Elements: Foundations of Matter (Chapter 4 Study Notes)

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