Define electronegativity.
Explain how electronegativity changes across a period.
P-Cl and S-Cl are both polar bonds. The electronegativity values for each element are given in the following table.
Element | Electronegativity |
|---|---|
phosphorus | 2.1 |
sulfur | 2.5 |
chlorine | 3.0 |
Identify which bond is more polar. Justify your answer.
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Describe how sodium chloride forms in terms of electron transfer.
Explain why sodium chloride has a higher melting point than carbon dioxide.
Explain how the difference in electronegativity between atoms determines whether a bond is ionic or covalent.
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The table below shows the bonds found in different molecules.
Bond |
|---|
H-H |
O=O |
N |
Identify which bond is the shortest. Justify your answer in terms of bond order.
The bond energy of a C-H bond in methane (CH₄) is 412 kJ/mol, while the bond energy of an H-F bond in hydrogen fluoride (HF) is 565 kJ/mol.
i) Explain why the H-F bond has a higher bond energy than the C-H bond in terms of atomic structure.
ii) Predict whether the bond length in H-F is longer or shorter than in C-H. Justify your answer.
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What is meant by a dipole moment?
Carbon dioxide and water both contain polar bonds.
Identify which molecule has a net dipole moment. Justify your answer in terms of molecular geometry.
The dipole moment of NH₃ is greater than that of NF₃ despite both having a trigonal pyramidal shape.
(i) Explain how the electronegativity of fluorine compared to hydrogen affects the dipole moment of NF₃ and NH₃.
(ii) Explain why the dipole moment of NH₃ is greater than that of NF₃ in terms of electron distribution and molecular polarity.
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Compare the bonding in metals and ionic solids in terms of electron behavior and the forces that hold the structure together.
(i) Explain why metals are malleable, whereas ionic solids are brittle, in terms of atomic structure and bonding.
(ii) Describe how the application of an external force affects the structure of a metal compared to an ionic solid.
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State Coulomb's law and identify its variables.
Identify which compound, potassium bromide or potassium sulfide, has the stronger electrostatic attraction. Justify your answer in terms of Coulomb’s Law.
The experimental lattice energy of NaCl deviates from Coulomb’s Law predictions.
(i) Explain how polarizability affects the lattice energy of NaCl
(ii) Explain how partial covalent character contributes to this deviation.
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