Question 1

Which of the following statements about elements is correct?

Accepted Answer

Elements are pure substances from which all other things are built.

Question 2

Which of the following is the correct chemical symbol for potassium?

Accepted Answer

K

Question 3

Which group on the periodic table contains the noble gases?

Accepted Answer

Group 8A (18)

Question 4

Which of the following best describes a metalloid?

Accepted Answer

A substance with properties intermediate between metals and nonmetals.

Question 5

According to Dalton’s Atomic Theory, which statement is FALSE?

Accepted Answer

Atoms are created and destroyed during chemical reactions.

Question 6

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

Accepted Answer

Ernest Rutherford’s gold foil experiment

Question 7

What is the mass number of an atom with 15 protons, 16 neutrons, and 15 electrons?

Accepted Answer

$$31$$

Question 8

A neutral atom of magnesium has an atomic number of $$12$$ and a mass number of $$24. $$How many neutrons does it have?

Accepted Answer

$$12$$

Question 9

Which of the following statements about isotopes is TRUE?

Accepted Answer

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

Question 10

Gallium has two naturally occurring isotopes: $$^{69}\mathrm{Ga} (68.926 $$amu, 60.10%) and $$^{71}\mathrm{Ga} (70.925 $$amu, 39.90%). What is the average atomic mass of gallium? (Round to two decimal places)

Accepted Answer

$$69.13$$ amu

Question 11

Which of the following electron configurations represents a neutral atom of nitrogen?

Accepted Answer

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

Question 12

How many unpaired electrons are present in a neutral atom of fluorine ($$F$$)?

Accepted Answer

$$1$$

Question 13

Which element has the ground-state electron configuration $$[Ne]3s^2$ 3p^5$?

Accepted Answer

Chlorine

Question 14

Which of the following elements is most likely to have electrons in the $$3p$$ sublevel?

Accepted Answer

Sulfur

Question 15

Which element has the largest atomic radius among the following?

Accepted Answer

Potassium ($$K)$$

Question 16

Which element has the highest ionization energy?

Accepted Answer

Helium ($$He)$$

Question 17

Which of the following best describes the trend in metallic character on the periodic table?

Accepted Answer

Metallic character increases down a group and decreases across a period from left to right.

Question 18

How many valence electrons does a neutral atom of silicon ($$Si) $$have?

Accepted Answer

$$4$$

Question 19

Which of the following is the correct Lewis symbol for magnesium ($$Mg$$)?

Accepted Answer

$$\mathrm{Mg} \cdot\cdot$$

Question 20

Which of the following statements about electron energy levels is TRUE?

Accepted Answer

The energy of an electron is quantized and increases as the principal quantum number $$n$$ increases.

Atoms and Elements: Structure, Symbols, and the Periodic Table

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