Chemistry Covalent Compounds Quiz

Questions and Answers

What occurs when an atom has a high electronegativity value in a covalent bond?

Attraction of the shared electrons towards itself (correct)

Decreased bond strength

Formation of a nonpolar bond

Increased electron sharing

Which electronegativity value range is indicative of a polar covalent bond?

1.7 to 2.5

Greater than 2.5

0.4 to 1.7 (correct)

0.0 to 0.4

What is a primary reason that covalent substances typically do not conduct electricity?

They have too many ions

They are always solids at room temperature

They lack free-moving electrons (correct)

They form ionic bonds instead

What is the expected effect of impurities on the melting point of recrystallized benzoic acid?

It lowers the melting point and widens the range Signup and view all the answers

What type of bond would form with an electronegativity difference greater than 1.7?

Ionic bond Signup and view all the answers

What phenomenon occurs when soluble impurities are dissolved during recrystallization?

They remain in solution Signup and view all the answers

Why is it essential to keep all equipment hot during the recrystallization of benzoic acid?

To prevent crystallization of benzoic acid in solution Signup and view all the answers

In the test for nitrates, what result indicates a positive outcome with Iron II sulfate and concentrated sulfuric acid?

A brown ring forms at the bottom Signup and view all the answers

What happens when ammonia is added to a solution containing chloride ions?

The precipitate dissolves Signup and view all the answers

What is formed when magnesium sulfate is added to a solution containing carbonate ions?

A white precipitate is formed Signup and view all the answers

What characteristic of covalent bonds distinguishes them from ionic bonds?

They involve the sharing of electrons. Signup and view all the answers

What is the primary reason that molecular compounds typically do not conduct electricity?

They do not dissociate into ions. Signup and view all the answers

What defines the difference between a sigma bond and a pi bond?

A sigma bond is stronger than a pi bond. Signup and view all the answers

Which statement best describes the characteristic of polar covalent bonds?

Electrons are shared unequally between two atoms. Signup and view all the answers

How does the Octet Rule influence the behavior of atoms during bonding?

Atoms aim to have eight valence electrons by sharing or transferring electrons. Signup and view all the answers

How does valency impact the formation of a compound?

Valency indicates the number of bonds an atom can form based on its outer electrons. Signup and view all the answers

What distinguishes lone pairs from bond pairs in covalent bonding?

Bond pairs share electrons while lone pairs do not. Signup and view all the answers

What characteristic is responsible for the high melting and boiling points of ionic compounds?

Strong electrostatic forces between charged ions. Signup and view all the answers

What is the primary difference between an atom and an ion?

An atom has a neutral charge, while an ion has a charge due to loss or gain of electrons. Signup and view all the answers

Study Notes

Covalent and Ionic Compounds

Covalent compounds do not conduct electricity in molten state or solutions because they do not dissociate into ions.
Ionic compounds exhibit high melting and boiling points due to strong electrostatic forces between oppositely charged ions.

Bonding Types

A σ (sigma) bond results from end-on overlapping of orbitals, while a π (pi) bond forms from the sideways overlap of p-orbitals.
Electrons involved in a covalent bond are known as bond pairs; non-bonding electrons are called lone pairs.
Covalent compounds are characterized by electron sharing, in contrast to ionic compounds where charge transfer occurs.

Molecular Characteristics

Polar covalent bonds are defined by unequal electron sharing between two atoms, leading to partial charges.
The Octet Rule dictates that atoms prefer to have eight electrons in their outer energy level during chemical bonding.
Atoms are neutral, while ions carry charge, with ionic bonding involving the attraction of oppositely charged ions.

Valency and Electronegativity

Valency indicates the number of bonds an atom can form, essential for achieving stable electronic configurations in compounds.
Electronegativity measures an atom's attraction to shared electrons in a covalent bond, influencing the bond's polarity.

Predicting Bond Types

The type of bond can be predicted based on electronegativity differences:
- Nonpolar covalent when difference is less than 0.4
- Polar covalent when between 0.4 and 1.7
- Ionic when greater than 1.7

Physical Properties of Covalent Substances

Covalent substances typically possess low melting and boiling points.

Experimental Techniques

Recrystallization is employed to purify benzoic acid by removing impurities.
Keeping equipment hot during this process prevents recrystallization of benzoic acid in solution.
Soluble impurities are washed away while the pure compound solidifies.
Melting point measurement of recrystallized benzoic acid indicates purity; the presence of impurities lowers the melting point and broadens the range.

Chemical Tests

A brown ring at the bottom of a test tube indicates the presence of nitrates when Iron II sulfate and sulfuric acid are added.
The precipitate formed from chloride ions dissolves upon the addition of ammonia.
Adding magnesium sulfate to a solution containing carbonate ions results in the formation of a white precipitate.

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Description

Test your knowledge on covalent and ionic compounds with this quiz. Understand why covalent compounds do not conduct electricity and what characteristics give ionic compounds their high melting and boiling points. Explore the differences between sigma and pi bonds as well.