The bond between the chlorine atoms in a chlorine molecule (Cl₂) is a pure (non-polar) covalent bond, whereas the bond between the chlorine atom and the hydrogen atom in the hydrogen chloride molecule (HCl) is a polar covalent bond - Leaving Cert Chemistry - Question 7 - 2007
Question 7
The bond between the chlorine atoms in a chlorine molecule (Cl₂) is a pure (non-polar) covalent bond, whereas the bond between the chlorine atom and the hydrogen ato... show full transcript
Worked Solution & Example Answer:The bond between the chlorine atoms in a chlorine molecule (Cl₂) is a pure (non-polar) covalent bond, whereas the bond between the chlorine atom and the hydrogen atom in the hydrogen chloride molecule (HCl) is a polar covalent bond - Leaving Cert Chemistry - Question 7 - 2007
Step 1
Define (i) covalent bond
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Answer
A covalent bond involves the sharing of electron pairs between atoms. This type of bond typically forms between non-metal atoms that have similar electronegativities.
Step 2
Define (ii) ionic bond
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An ionic bond involves the attraction of oppositely charged ions formed by the transfer of electrons. This generally occurs between metals and non-metals.
Step 3
Draw dot and cross diagrams showing the formation of the bonds in (i) Cl₂
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Answer
In Cl₂, each chlorine atom has 7 valence electrons. They each share 1 electron to form a covalent bond, resulting in a total of 1 shared pair.
Step 4
Draw dot and cross diagrams showing the formation of the bonds in (ii) HCl
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In HCl, there is 1 hydrogen atom with 1 electron and 1 chlorine atom with 7 valence electrons. They share 1 electron to form a single covalent bond, resulting in the formation of 1 shared pair.
Step 5
Draw dot and cross diagrams showing the formation of the bonds in (iii) NaCl
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In NaCl, 1 sodium atom with 1 valence electron transfers that electron to a chlorine atom which has 7 valence electrons. This results in the formation of Na⁺ and Cl⁻ ions.
Step 6
What is meant by a polar bond? Explain why the bond in the HCl molecule is polar.
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A polar bond is characterized by the unequal sharing of electrons between atoms due to differences in their electronegativities. In the HCl molecule, chlorine is more electronegative than hydrogen; hence, it attracts the shared electron pair closer, creating a dipole moment.
Step 7
Which of the substances, chlorine or sodium chloride, would you expect to be more soluble in water? Give a reason for your answer.
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Sodium chloride is expected to be more soluble in water. This is because it is an ionic substance, and water is a polar solvent, allowing it to effectively dissolve ionic compounds.
Step 8
Name the solution.
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The solution is hydrochloric acid.
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