Question 1

Which of the following statements best describes the atomic number of an element?

Accepted Answer

It is the number of protons in the nucleus.

Question 2

A neutral atom of sodium (Na) has an atomic number of 11. How many electrons does it have?

Accepted Answer

$11$

Question 3

Which of the following elements is a metalloid?

Accepted Answer

Silicon (Si)

Question 4

An isotope of chlorine has a mass number of $37$ and an atomic number of $17$. How many neutrons does it have?

Accepted Answer

$20$

Question 5

Which group of the periodic table contains the noble gases?

Accepted Answer

Group 8A

Question 6

A sample of magnesium contains $3.01 	imes 10^{22}$ atoms. How many moles of magnesium are present in the sample? ($1$ mol $= 6.022 	imes 10^{23}$ atoms)

Accepted Answer

$0.0500$ mol

Question 7

Which of the following best describes a cation?

Accepted Answer

An atom that has lost electrons and is positively charged.

Question 8

Which of the following elements is most likely to form a $2+$ ion?

Accepted Answer

Magnesium (Mg)

Question 9

A copper penny has a mass of $3.10$ g. Given that the molar mass of copper is $63.55$ g/mol, how many atoms of copper are in the penny? ($1$ mol $= 6.022 	imes 10^{23}$ atoms)

Accepted Answer

$2.94 	imes 10^{22}$ atoms

Question 10

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 11

Which of the following elements is a halogen?

Accepted Answer

Chlorine (Cl)

Question 12

Calculate the atomic mass of an element that has two isotopes: $70.00\%$ abundance of isotope A with mass $10.00$ amu and $30.00\%$ abundance of isotope B with mass $11.00$ amu.

Accepted Answer

$10.30$ amu

Question 13

Which of the following is a property of metals?

Accepted Answer

They are good conductors of heat and electricity.

Question 14

Which of the following best describes the relationship between atomic mass and molar mass?

Accepted Answer

The atomic mass in amu is numerically equal to the molar mass in grams per mole.

Question 15

A stable atom of oxygen has an atomic number of $8$. How many electrons does an $O^{2-}$ ion have?

Accepted Answer

$10$

Question 16

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

Accepted Answer

Nitrogen (N)

Question 17

Which of the following best explains why elements in the same group of the periodic table have similar chemical properties?

Accepted Answer

They have the same number of valence electrons.

Question 18

How many moles of carbon are present in a $0.0265$ g sample of graphite? (Molar mass of C = $12.01$ g/mol)

Accepted Answer

$2.21 	imes 10^{-3}$ mol

Question 19

Which of the following statements about metalloids is correct?

Accepted Answer

They have properties intermediate between metals and nonmetals.

Question 20

Which of the following ions has the same number of electrons as a neutral atom of neon ($Z=10$)?

Accepted Answer

$\mathrm{Na}^+$

Atoms and Elements: Structure, Periodic Table, and Atomic Mass

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