The atoms in a water molecule are joined by covalent bonds - Leaving Cert Chemistry - Question b - 2017
Question b
The atoms in a water molecule are joined by covalent bonds.
(i) Explain the underlined term.
(ii) Draw a dot and cross diagram showing the bonding in a water molec... show full transcript
Worked Solution & Example Answer:The atoms in a water molecule are joined by covalent bonds - Leaving Cert Chemistry - Question b - 2017
Step 1
Explain the underlined term.
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Answer
Covalent bonds are formed by the attraction between a shared pair of electrons from two atoms. In this type of bonding, atoms share electrons to achieve stability and full outer electron shells.
Step 2
Draw a dot and cross diagram showing the bonding in a water molecule.
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Answer
The dot and cross diagram for a water molecule (H₂O) illustrates that oxygen has 6 valence electrons and shares one with each of the two hydrogen atoms, represented as follows:
H •
|
O:
\
H •
In the diagram, the dots represent the electrons from hydrogen and the crosses represent the electrons from oxygen.
Step 3
What is the shape of a water molecule?
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Answer
The shape of a water molecule is V-shaped or angular due to the two lone pairs of electrons on the oxygen atom, which repel the hydrogen atoms.
Step 4
Define electronegativity.
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Answer
Electronegativity is a relative measure of an atom's ability to attract shared electrons in a chemical bond. Higher electronegativity values indicate a stronger attraction for electrons.
Step 5
Use electronegativity values to explain why the bonds in water are polar covalent and not pure covalent.
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Answer
The electronegativity difference between oxygen (2.34) and hydrogen (2.20) is 1.24, indicating that the bonds are polar covalent. This is because the oxygen atom has a stronger attraction for the shared electrons than hydrogen, resulting in a partial negative charge on the oxygen and a partial positive charge on the hydrogen atoms.
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