Module 2 Chapter 6 -shape Of Molecules And Forces Flashcards
Predict the shape of a molecule of SbCl3.
Explain your answer
Pyramidal
Because SbCl3 has 3 bonding pairs and one lone pair of electrons. The pair of electrons repel.
SbCl3 molecules are polar.
Explain your answer.
There is a difference in electronegativities between Sb and Cl.
The molecule is not symmetrical and the dipoles do not cancel
State and explain two anomalous properties of ice caused by hydrogen bonding.
- Ice is less dense than water because the molecules in ice are held together by hydrogen bonds.
- Ice has a relatively high melting point because hydrogen bonds are stronger and more energy is required to break the bonds.
Explain what is meant by the term electronegativity
Electronegativity is the ability of an atom to attract the pair of electrons in a covalent bond
Explain why CH2Cl2 molecule is polar
The molecule is non symmetrical and the dipoles do not cancel out
Predict the shape and bond angle in a molecule that has 2 bonding pairs and 2 lone pairs around a central atom.
Non linear - 104.5°
Suggest the shape of the F2O molecule and the bond angle
Non linear
104.5°
What is the oxidation number of oxygen in F2O?
2+
Describe how london forces arise
Both atoms have an even distribution of electrons,
for the fraction of time there is an uneven distribution of electrons which creates an instantaneous dipole
Meaning the neighbouring molecule produces an induced dipole
Suggest why there are no other intermolecular forces in solid sulfur
There’s only one atom - no permanent dipole
State and explain the trend in the boiling points of chlorine, bromine and iodine.
Use ideas of london forces
As you go down the group, the boiling point increases because there is a greater number of electrons and stronger london forces therefore more energy is needed to break the london forces.
Which substances experiences induced dipole dipole interactions (London forces)?
- C2H5OH
- H2O
- SiO2
Only 1 and 2
What happens to the trend in boiling points down the halogen group?
The induced dipole-dipole interactions(London Forces) increases
Magnesium and silicon have different types of giant structures.
Describe the bonding in magnesium and in silicon.
Include the names of the particles and describe the forces between the particles in the structure.
Magnesium is a metallic bond and they have delocalised electrons to be able to conduct electricity.
Silicon is a covalent bond and occurs between atoms
Magnesium and silicon have different types of giant structures.
Describe the bonding in magnesium and in silicon.
Include the names of the particles and describe the forces between the particles in the structure.
Magnesium is a metallic bond and they have delocalised electrons to be able to conduct electricity.
Silicon is a covalent bond and occurs between atoms
At room temperature and pressure, the first 4 members of the alkanes are all gases but the first four alcohols are all liquids.
Explain this difference in terms of intermolecular forces.
Alcohols have hydrogen bonds and London forces
Hydrogen bonds are the strongest bond out of the three, and alkanes only have London forces.
Explain why a CF4 molecule has polar bonds but does not have an overall dipole.
F is more electronegative than C
CF4 is symmetrical as it forms a tetrahedral shape therefore there is no overall dipole
The boiling point of butan-1-ol is 118 degrees. The boiling point of 2-methypropan-2-ol is 82 degrees. Why is the boiling point of butan-1-ol higher than that of 2-methylpropan-2-ol?
Butan-1-ol has stronger induced dipole-dipole interactions because it has a straight chain structure
Explain what is meant by the term electronegativity and suggest why SF6 molecules are non polar.
The ability of an atom to attract electrons in a covalent bond. Because SF6 is a symmetrical shape
State and explain the trend in the boiling points of chlorine, bromine and iodine.
As you go down the group the boiling point increases because there is a greater number of electrons and stronger London forces therefore more energy is needed to break the London forces.
What is the shape name and bond angle of a shape that has 4BP and 0LP
Tetrahedral
109.5 degrees
What is the shape name and bond angle of a shape that has 3BP and 1LP
Trigonal Pyramidal
107
What is the shape name and bond angle of a shape that has 2 BP and 2LP
Bent/Non linear
104.5
What is the shape name and bond angle of a shape that has 3BP and 0LP
trigonal planar
120 degrees
What is the shape name and bond angle of a shape that has 2BP and 0LP
Linear
180
What is the shape name and bond angle of a shape that has 5BP and 0LP
trigonal bipyramidal
120/90
What is the shape name and bond angle of a shape that has 6BP and 0LP
Octahedral
90
What is the shape name and bond angle of a shape that has 2BP and 1LP
Bent/Non linear - <120
State the shape and bond angle around a carbon atom in the alkyl group of propanoic acid .
Explain the shape
Tetrahedral
109°
Four bonded pairs repel
