High School Chemistry : Compounds and Bonding

Study concepts, example questions & explanations for High School Chemistry

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Example Questions

Example Question #4 : Help With Molecular Formulas

Which of the following options contains only compounds with covalent bonds?

Possible Answers:

Correct answer:

Explanation:

Ionic bonds generally occur between metal and nonmetal ions, while covalent bonds usually occur between two nonmetal atoms. The compounds containing sodium, iron, silver, calcium, and rubidium will all contain ionic bonds involving these elements.

The answer  is the only answer without any metal atoms, indicating that the bonds in these molecules will be covalent.

Example Question #1 : Help With Molecular Formulas

Which of these molecules will not demonstrate hydrogen bonding?

Possible Answers:

Correct answer:

Explanation:

Hydrogen bonds are present in molecules in which hydrogen atoms are bound to highly electronegative atoms, namely oxygen, fluorine, or nitrogen. These bonds are extremely polar, resulting in a partial positive charge on the hydrogen atoms and a partial negative charge on the more electronegative atom.

Of the given answer options, methane (), is the only one that does not involve a hydrogen atom bound to an oxygen, nitrogen, or fluorine. It cannot demonstrate hydrogen bonding.

Note that glucose (), as well as most other sugars, contain aldehyde or hydroxyl groups. These consist of -OH bonds, which allow for hydrogen bonding.

Example Question #31 : Compounds And Bonding

Sodium will react with oxygen and form an ionic compound. Which of the following is false concerning this interaction?

Possible Answers:

The electrons are not equally shared between sodium and oxygen

The ionic compound has an overall neutral charge

Sodium has a higher electronegativity than oxygen, causing it to give its electron to oxygen

Both oxygen and the two sodiums are given stable octets by creating the ionic compound

In this compound, oxygen is the anion while the two sodium atoms are defined as cations

Correct answer:

Sodium has a higher electronegativity than oxygen, causing it to give its electron to oxygen

Explanation:

Electronegativity is defined as the tendency of an atom to attract an electron in a bond that it shares with another atom. Because oxygen wants to receive two elctrons, while both sodiums wish to lose one electron, oxygen has a higher electronegativity than sodium. Typically, electronegativity can be seen as increasing as you go to the top right of the periodic table. For example, fluorine has a higher electronegativity than nitrogen.

Example Question #2 : Help With Ionic Bonds

Ionic bonds most commonly form between which of the following?

Possible Answers:

Two non-metals

Metal and nonmetal

A transition metal and a metalloid

A metalloid and a metal

Two metals

Correct answer:

Metal and nonmetal

Explanation:

Ionic bonds most commonly form between metals and non-metals. Non-metals have high electronegativities and metals have low electronegativities. In these type of bonds, electrons are transferred from the metal to the non-metal because of the large difference in electronegativities. The non-metal will try to gain an electron (high electronegativity) and the metal will try to donate an electron (low electronegativity). The result is a complete electron transfer, known as an ionic bond.

Example Question #3 : Help With Ionic Bonds

A large difference in which atomic property between two atoms will result in an ionic bond?

Possible Answers:

Atomic mass

Ionic radius

Atomic charge

Ionization energy

Electronegativity

Correct answer:

Electronegativity

Explanation:

Electronegativity is the tendency of an atom to attract an electron. Elements with very high electronegativities are found at the upper right of the periodic table, while those with low electronegativities are found at the lower left. When two atoms have a very large difference in electronegativity, one atom will have a much greater tendency to attract an electron than the other. As a result, the more electronegative element will pull an electron away from the less electronegative element, creating an electron transfer. This transfer is an ionic bond.

Most non-metals have very high electronegativities, while most metals have very low electronegativities. This is why ionic bonds usually form between a metal atom and a non-metal atom.

Example Question #4 : Help With Ionic Bonds

Which of the following describes ionic bonds?

Possible Answers:

An electron is donated from one atom to another

Ionic bonds are weak, transient bonds between two water molecules

A proton is donated from one atom to another

An electron is shared between two atoms

A proton is shared between two atoms

Correct answer:

An electron is donated from one atom to another

Explanation:

There are two primary types of intramolecular bonds: ionic bonds and covalent bonds. In an ionic bond, an electron is transferred (donated) from one atom to the other, usually allowing both atoms to satisfy the octet rule. In a covalent bond, electrons are shared between two atoms in order to allow both to satisfy the octet rule.

Ionic bonds usually form between a metal and a non-metal. HCl, NaCl, and NaOH are all examples of molecules that contain ionic bonds.

Example Question #1 : Help With Ionic Bonds

Which of the following describes an ionic bond?

Possible Answers:

None of these

A type of chemical bond that involves the sharing of one or more electron pairs between atoms

A type of electrostatic interaction between polar molecules that occurs when a hydrogen atom binds to a highly electronegative atom such as oxygen, fluroine, or nitrogen

A type of chemical bond in which two anions combine to form a single compound

A type of chemical bond in which one or more electrons are transferred from one atom to another in order for both atoms to have a full valence shell

Correct answer:

A type of chemical bond in which one or more electrons are transferred from one atom to another in order for both atoms to have a full valence shell

Explanation:

Ionic bonds occur when there is a large electronegativity difference between two atoms, such as elemental between fluorine and potassium. The transfer of one electron will fill the valence electron shell of both atoms. Remember that ionic bonds result in ions, or charged species. A covalent bond is a chemical bond in which two atoms share one or more electrons, but the electron(s) is/are never fully donated or accepted.

Example Question #1 : Help With Ionic Bonds

Which of the following molecules has only ionic bonds?

Possible Answers:

Correct answer:

Explanation:

An ionic bond is a complete transfer of electrons between atoms which forms a cation and an anion. A metal (cation) tends to gain electron(s) and a non-metal tends to lose electron(s). Both act to satisfy their octets and the electrostatic attraction between the oppositely charged atoms holds them together.

Diatomic chlorine forms covalent bonds since they are equal in terms of electronegativities.

 forms a polar covalent bond based on the two atom's differing electronegativities, and on the fact that both atoms are nonmetals.

 has both ionic bonds (between the metal  and polyatomic ion) and covalent bonds within the polyatomic ion. Since we are only looking for ionic bonds,  is the correct answer.

Example Question #31 : Compounds And Molecules

Which compound has both ionic and covalent bonds?

Possible Answers:

Correct answer:

Explanation:

In , the nitrogen is bound covalently to the three oxygens, and the complex has an overall of .

Sodium has a charge of , and is ionically bound to the  complex.

When put into water, the compound will dissociate into  and .

HCl is an ionic compound, while the other answer choices have only covalent bonds.

Example Question #1 : Help With Covalent Bonds

Which of the following is not true of covalent bonds?

Possible Answers:

The elements in the bond have a large difference in electronegativity

The atoms in the bond have high electronegativities

The bond can be polar or nonpolar

Covalent bonds readily form between two non-metals

The bond can involve halogens

Correct answer:

The elements in the bond have a large difference in electronegativity

Explanation:

Covalent bonds form when two atoms share electrons, caused by an overlap of their orbitals. Each atom has a similar amount of "pull" on the electrons, preventing them from getting too close to one atom or the other and keeping them in the middle. This "pull" is the electronegativity. Atoms in covalent bonds have similar electronegativity values to keep the electrons in the center. When the electronegativities are slightly different, the electrons can lean toward one atom. The result is a polar bond, in which one atom is closer to the electrons (negative) and the other is farther (positive). Most non-metals have very high and very similar electronegativity values, and will readily form covalent bonds.

When the difference in electronegativity, or "pull," is too great, the electrons will be transferred from one atom to the other. The result is an ionic bond, which usually forms between a metal (low electronegativity) and a non-metal (high electronegativity).

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