Question 1

A sample contains 5 mmol of a compound with a molecular weight of 246 g/mol. What is the mass of the sample in grams? (Answer to two decimal places.)

Accepted Answer

$$1.23$$

Question 2

You have $$6.289 g of a $$solution of polyethylene glycol with a density of $$1.16 g/cm$^3. $$What volume do you have in mL? (Answer to 3 significant figures.)

Accepted Answer

$$5.42$$\ 	ext{mL}$

Question 3

A metal ion $$M^{3+}$$ has the electron configuration $$[Ar]3d^2$. Identify the metal M$.

Accepted Answer

Vanadium

Question 4

Which of the following correctly balances the combustion of butane ($$C_4H_{10}$$)?

$$C_4H_{10} (l) + O_2$ (g) \rightarrow CO_2$ (g) + H_2O (g)$$

Accepted Answer

$$2C_4H_{10} + 13O_2 \rightarrow 8CO_2 + 10H_2O$$

Question 5

Which element has a higher first ionisation energy: Boron or Carbon? Explain using periodic trends.

Accepted Answer

Carbon, because ionisation energy increases across a period.

Question 6

Which of the following pairs has the larger atomic radius?

Accepted Answer

Fluorine or Chlorine? Chlorine

Question 7

Which of the following statements about electron affinity is correct?

Accepted Answer

Electron affinity generally increases across a period.

Question 8

Which of the following best explains why ionisation energy decreases down a group?

Accepted Answer

The outer electrons are further from the nucleus and more shielded.

Question 9

Which of the following compounds is formed by the transfer of electrons from a metal to a non-metal?

Accepted Answer

Sodium chloride ($$NaCl)$$

Question 10

Which of the following best describes the octet rule?

Accepted Answer

Atoms gain, lose, or share electrons to achieve 8 electrons in their valence shell.

Question 11

Which of the following is the correct formula for magnesium nitrate, using the octet rule and ion charges?

Accepted Answer

$$Mg(NO_3$)_2$$

Question 12

Which of the following statements about covalent bonds is correct?

Accepted Answer

Covalent bonds involve the sharing of electrons between atoms.

Question 13

How many non-bonding valence electrons are present in a chlorine atom in a $$Cl_2$$ molecule?

Accepted Answer

6

Question 14

Draw a Lewis dot diagram for $$CO_2. $$What kind of bonds are present?

Accepted Answer

Two double bonds between C and O

Question 15

Which of the following best explains why fluorine has a higher electronegativity than chlorine?

Accepted Answer

Fluorine has a smaller atomic radius and a higher effective nuclear charge.

Question 16

Which of the following best describes the trend in atomic radius across a period?

Accepted Answer

Atomic radius decreases across a period due to increasing nuclear charge.

Question 17

Which of the following is a correct statement about the formation of $$MgCl_2$$?

Accepted Answer

Magnesium donates two electrons to two chlorine atoms, forming $$Mg^{2+}$$ and two $$Cl^-$$ ions.

Question 18

Which of the following best explains why noble gases have very low electron affinities?

Accepted Answer

They have full valence shells and do not readily accept electrons.

Question 19

Which of the following is the correct formula for aluminium sulfate, based on the charges of the ions?

Accepted Answer

$$Al_2$$($$SO_4)_3$

Question 20

Which of the following 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.

Periodic Trends and Chemical Bonding: Study Notes for General Chemistry

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