Question 1

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 2

A neutral atom of calcium-40 ($^{40}\mathrm{Ca}$) has how many protons, neutrons, and electrons?

Accepted Answer

20 protons, 20 neutrons, 20 electrons

Question 3

Which element is a metalloid and is commonly used in computer chips due to its semiconducting properties?

Accepted Answer

Silicon (Si)

Question 4

Which of the following best describes the trend in atomic radius as you move down a group in the periodic table?

Accepted Answer

Atomic radius increases because additional energy levels are added.

Question 5

Which of the following electron configurations represents a noble gas?

Accepted Answer

$1s^2\ 2s^2\ 2p^6$

Question 6

A sample of gallium contains 60.10% $^{69}\mathrm{Ga}$ (68.926 amu) and 39.90% $^{71}\mathrm{Ga}$ (70.925 amu). What is the average atomic mass of gallium? (Round to two decimal places)

Accepted Answer

$69.72\ \mathrm{amu}$

Question 7

Which of the following elements has the highest ionization energy?

Accepted Answer

Neon (Ne)

Question 8

Which of the following statements about the structure of the atom is FALSE?

Accepted Answer

A neutron has a negative charge.

Question 9

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

Accepted Answer

Chlorine (Cl)

Question 10

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

Accepted Answer

Metals have delocalized valence electrons that can move freely.

Question 11

Which of the following is the correct ground-state electron configuration for a neutral nitrogen atom ($Z=7$)?

Accepted Answer

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

Question 12

Which of the following elements is a halogen?

Accepted Answer

Bromine (Br)

Question 13

Which of the following statements about electromagnetic radiation is correct?

Accepted Answer

High-energy radiation has short wavelengths.

Question 14

How many unpaired electrons are present in a neutral fluorine atom ($Z=9$)?

Accepted Answer

1

Question 15

Which of the following best describes the Pauli exclusion principle?

Accepted Answer

Each orbital can hold a maximum of two electrons with opposite spins.

Question 16

Which of the following elements has the greatest metallic character?

Accepted Answer

Potassium (K)

Question 17

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

Accepted Answer

Mg with two dots on one side

Question 18

Which of the following best explains why noble gases are chemically unreactive?

Accepted Answer

They have a full valence shell of electrons.

Question 19

Which of the following is the correct order of filling for the sublevels as atomic number increases?

Accepted Answer

$1s \rightarrow 2s \rightarrow 2p \rightarrow 3s \rightarrow 3p \rightarrow 4s \rightarrow 3d$

Question 20

A certain element has the electron configuration $[\mathrm{Ne}]\ 3s^2\ 3p^5$. What is the element and how many valence electrons does it have?

Accepted Answer

Chlorine (Cl), 7 valence electrons

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

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