Define electronegativity.
Draw dot and cross diagrams to show the bonding in a molecule of
(i) nitrogen trifluoride (NF₃),
(ii) boron trifluoride (BF₃),
(iii) ch... show full transcript
Worked Solution & Example Answer:Define electronegativity - Leaving Cert Chemistry - Question b - 2017
Step 1
Define electronegativity.
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Answer
Electronegativity is a number expressing the relative attraction of an atom for shared pairs of electrons in a covalent bond. It measures the tendency of an atom to attract bonding electrons.
Step 2
(i) nitrogen trifluoride (NF₃)
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In the dot and cross diagram for nitrogen trifluoride:
F F
| |
•N• •N•
| |
F F
Here, nitrogen shares its electrons with three fluorine atoms.
Step 3
(ii) boron trifluoride (BF₃)
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The dot and cross diagram for boron trifluoride is:
F F
| |
•B• •B•
| |
F F
In this case, boron shares its electrons with three fluorine atoms as well.
Step 4
(iii) chlorine monofluoride (ClF)
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The dot and cross diagram for chlorine monofluoride is:
•Cl•
|
F
Chlorine shares one electron with fluorine to form a covalent bond.
Step 5
Use electron pair repulsion theory to predict the shape of a molecule of boron trifluoride.
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According to the electron pair repulsion theory, boron trifluoride (BF₃) has a trigonal planar shape. This occurs because the three fluorine atoms repel each other, leading to an arrangement that minimizes repulsion.
Step 6
(iv) indicate on your bonding diagram for chlorine monofluoride any full or partial charges that you would expect to result from the formation of the bond between chlorine and fluorine.
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In the bonding diagram for ClF:
•Cl• δ+
|
F δ−
Chlorine has a partial positive charge (δ+) and fluorine has a partial negative charge (δ−).
Step 7
(v) predict the type of bonding in chlorine monofluoride.
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The bonding in chlorine monofluoride is polar covalent due to the difference in electronegativity between chlorine and fluorine, which leads to an unequal sharing of electrons.
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