Q: Calculate the molar mass of Fe(OH)$$_3$$ using the following atomic masses: Fe = 55.85 g/mol, O = 16.00 g/mol, H = 1.01 g/mol.

$$55.85 + 3 \times (16.00 + 1.01) = 106.88 g/$$mol

Q: If a compound contains Ca, Mg, and CO$$_3$$, what is its molar mass? (Ca = 40.08 g/mol, Mg = 24.31 g/mol, C = 12.01 g/mol, O = 16.00 g/mol)

$$40.08 + 24.31 + 2 \times (12.01 + 3 \times 16.00) = 184.41 g/$$mol

Q: A green building project emits 43 metric tons of CO$$_2$$ per apartment. How many metric tons of carbon are emitted by a 20-unit building? (Molar mass of CO$$_2 = 44 g/$$mol, molar mass of C = 12 g/mol)

$$\frac{43 \times 20 \times 12}{44} = 235$$ metric tons$

Question 1

Which statement best explains why noble gases are generally unreactive?

Accepted Answer

They have a full set of valence electrons, satisfying the octet rule.

Question 2

What is the electron configuration for fluorine (atomic number 9)?

Accepted Answer

$$1s^22s^22$p^5$$

Question 3

Which element is most likely to form a cation by losing one electron?

Accepted Answer

Sodium (Na)

Question 4

Why can magnesium (Mg) substitute for calcium (Ca) in dolomite minerals?

Accepted Answer

Mg and Ca have similar ionic radii and charges, allowing Mg to swap for Ca in the crystal lattice.

Question 5

Calculate the molar mass of Fe(OH)$$_3$$ using the following atomic masses: Fe = 55.85 g/mol, O = 16.00 g/mol, H = 1.01 g/mol.

Accepted Answer

$$55.85 + 3 	imes (16.00 + 1.01) = 106.88 g/$$mol

Question 6

Which of the following best describes the octet rule?

Accepted Answer

Atoms tend to gain, lose, or share electrons to achieve eight valence electrons.

Question 7

What type of bond is formed when sodium reacts with chlorine?

Accepted Answer

Ionic bond

Question 8

Which of the following is the correct name for the compound MgO?

Accepted Answer

Magnesium oxide

Question 9

A transition metal can have multiple ionic charges. How is this indicated in the name of an ionic compound?

Accepted Answer

By using Roman numerals to denote the charge, e.g., iron(III) chloride.

Question 10

Which of the following elements is most likely to form a triple covalent bond?

Accepted Answer

Nitrogen (N)

Question 11

What is the electronegativity difference between hydrogen (H, $$\chi = 2.1) $$and chlorine (Cl, $$\chi = 3.0$$), and what type of bond do they form?

Accepted Answer

$$3.0 - 2.1 = 0.9$$; polar covalent bond

Question 12

Which of the following best describes a polar covalent bond?

Accepted Answer

A bond in which electrons are shared unequally between atoms with different electronegativities.

Question 13

If a compound contains Ca, Mg, and CO$$_3$$, what is its molar mass? (Ca = 40.08 g/mol, Mg = 24.31 g/mol, C = 12.01 g/mol, O = 16.00 g/mol)

Accepted Answer

$$40.08 + 24.31 + 2 	imes (12.01 + 3 	imes 16.00) = 184.41 g/$$mol

Question 14

Which of the following ions is commonly encountered in soils and can be repelled by negatively charged soil particles, leading to leaching?

Accepted Answer

Nitrate ($$NO_3$$^-$$)

Question 15

Which of the following best describes the process by which sodium becomes a sodium ion?

Accepted Answer

Sodium loses one electron to achieve a stable electron configuration like neon.

Question 16

Which of the following is the correct Lewis dot structure for oxygen?

Accepted Answer

$$\cdot\cdot O \cdot\cdot$$

Question 17

A green building project emits 43 metric tons of CO$$_2$$ per apartment. How many metric tons of carbon are emitted by a 20-unit building? (Molar mass of CO$$_2 = 44 g/$$mol, molar mass of C = 12 g/mol)

Accepted Answer

$$\frac{43 	imes 20 	imes 12}{44} = 235$$ metric tons$

Question 18

Which of the following elements is most likely to form a nonpolar covalent bond with itself?

Accepted Answer

Oxygen (O$$_2)$$

Question 19

Which statement best describes the difference between ionic and covalent bonds?

Accepted Answer

Ionic bonds involve the transfer of electrons, while covalent bonds involve the sharing of electrons.

1) The Octet Rule & Chemical Bonding: Introductory Chemistry Study Notes

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