Molecules: Shapes and Forces - exam practice
Molecules: Shapes and Forces
Question 1 of 9
State the meaning of the term electronegativity.
The table below shows the Pauling electronegativity values of some Period 3 elements.
Deduce the type of bonding in sulfur hexachloride, SCl6.
Explain your reasoning, using the table of electronegativity values above.
Draw the shape of a molecule of SF6. Include a value of the F-S-F bond angle.
Explain why SF6 has the shape you have drawn.
This question is about the group 3 element boron.
Boron trifluoride can react with a fluoride ion as shown by the equation;
BF3 + F- ➔ BF4-
Draw a diagram to show the shape of the BF3 molecule.
State its shape.
Explain why the BF3 molecule has the shape that you have drawn in part a).
Draw a diagram to show the shape of the BF4- ion.
State its shape.
Name the type of bond formed in the reaction between BF3 and F- to form BF4-.
Explain how this bond is formed in terms of electrons involved.
The diagram below represents a molecule of hydrogen peroxide.
Predict a value for the H-O-O bond angle.
Hydrogen peroxide dissolves in water.
State the strongest type of interaction that occurs between molecules of hydrogen peroxide and water.
Draw a diagram to show how one molecule of hydrogen peroxide interacts with one molecule of water.
Include all lone pairs and partial charges in your diagram.
Explain, in terms of electronegativity, why the boiling point of H2O2 is higher than H2S2.
Draw a diagram to show the shape of a molecule of ammonia. Include any lone pairs of electrons and give the value of the bond angle.
What is the name of the shape of the ammonia molecule, NH3?
Ammonia, NH3, can react with a hydrogen ion, H+, to form an ammonium ion, NH4+, which contains a dative covalent bond.
Explain how the dative covalent bond in NH4+ is formed.
State the new shape and bond angle of the ammonium ion.
Ammonia reacts with aluminium chloride as shown by the equation:
NH3 + AlCl3 ➔ H3NAlCl3
Draw a diagram to illustrate the shape of a molecule of AlCl3.
Give the value of the bond angle.
Name the type of bond formed between N and Al in H3NAlCl3.
Explain how the value of the Cl-Al-Cl bond angle in AlCl3 changes, if at all, on formation of the compound H3NAlCl3.
This question is about H2O.
State the strongest type of interaction between molecules of water.
Draw a diagram to show hydrogen bonding between two molecules of H2O.
Include all lone pairs and partial charges in your diagram.
Label the hydrogen bond.
Hydrogen bonding in ice causes ice to have a lower density than water and ice to have a relativity high melting point.
Explain why hydrogen bonding causes ice to have these anomalous properties.
This question is about the element hydrogen and its compounds.
Lithium amide (LiNH2) contains the amide ion, NH2-.
Draw the shape of the amide ion, NH2-
Include any lone pairs and give the value of the bond angle.
Describe the requirements for hydrogen bonding between two molecules, A and B.
The table below shows the boiling points of ammonia, NH3, and hydrogen, H2.
Explain the difference in boiling points.
This question is about intermolecular forces.
The table below shows some electronegativity values of some elements.
Using the data in the table above, predict the formula of the compound with the most polar bonds formed from two of these elements.
The Si-Cl bond is polar.
Explain why SiCl4 is not a polar molecule.
State the strongest type of intermolecular force that exists between molecules of SiCl4.
Explain how induced dipole-dipole forces arise in a sample of SiCl4.
Suggest, in terms of intermolecular forces, why SiCl4 has a higher boiling point than SiHCl3.
The table below shows some average bond enthalpies.
Compare the relative bond strength of the C-C single and C=C double bonds.
Explain your answer.
Trichloroethene, C2HCl3, is a polar molecule.
Annotate the diagram below to show the direction of the dipole in a molecule of trichloroethene.
Include partial charges.
The boiling points of trichloroethene, C2HCl3, and tetrachloroethene, C2Cl4, are shown in the table below.
Suggest, in terms of intermolecular forces, why C2Cl4 has a higher boiling point than C2HCl3.