Unit 16
Assignment 1
11053457
Part b)
From the graph we can conclude that there is a direct relationship between the number of
carbon atoms, and the melting and boiling points of alkanes. As the boiling point increases
the number of carbon atoms also increases as a result of the increased intermolecular
forces. The van der Waal’s forces are greater in a larger in a larger molecule as the surface
area is higher thus there is greater chance of interconnections between the molecules.
The van der Waal’s forces is also greater due to the lengthy of the chain; as there is a
greater number of electrons present and the molecular mass being higher there is a greater
chance of interactions between the molecules. As a result more energy is required to break
the forces between the chains. On the other hand this trend does not appear as a smoothly
in the melting point as there is a difference between the odd and even numbered carbon
chains. The odd numbered carbon chains cannot pack together tightly in the solid phase
thus the separation of the chains are much easier and require less energy resulting in a
lower melting and boiling points. However the even numbered carbon chains can pack
together in the solid phase thus more energy is required separate the chains.
There is also a direct relationship between the number of carbon atoms and the melting and
the boiling points of the alcohol as a result of the increased Van der Waals’ forces. However
the boiling and melting points of alcohol are much greater than the alkanes even though their
number of carbon atoms are the same. This is a result of the OH group in the alcohols which
enables the formation of hydrogen bonds.Hydrogen bonds are much more stronger than der
Waals’ forces acting on them as well as hydrogen bonds.
Part c)
In an alcohol there are two parts: hydrophilic head and hydrophobic tail. Methanol, ethanol
and Propanol are Infinitely soluble in water due to the presence of OH group.
Hydrogen bonds can be formed between the alcohol and water molecules and the length of
the carbon chains is not long enough thus the Van de Waals’ forces between the chains will
not be strong enough to affect the solubility of the alcohol. However as the number of the
carbon atoms in the chain increases the solubility decreases as the Van der Waals’ forces
are stronger thus preventing the solubility.
Part d)
The elements in the graph goes across Period 3. Group 1-3 elements: Sodium, magnesium
and aluminium are the metals and they from metallic bonding by the attraction between
positive metal ions and delocalised electrons Sodium +1 Magnesium +2 and aluminium +3
shows that there is an increase in the positivity which results in the number of delocalised
electrons to increase thus the strength of the metallic bonding will be greater As a result of
the strong metallic bonding the boiling and the melting point increases
Group 4 element: silicon is a metalloid. It has giant covalent bonding and has giant lattice
structure similar to diamond thus the boiling and the melting point of silicon is higher as the
held together by strong covalent bonds. Thus more energy is required to break to bonds.
Group 0 5-8 elements: phosphorus, sulfur, chlorine and argon are all non-metals. The
elements are small ams separate molecules and exist as simple molecules with strong
covalent bonds between the atoms except Argon.Argon exist as separate atoms as it is a
noble gas and the outermost shell is full thus does not gain or lose electrons and as a result
in unreactive. The boiling and melting point of the melting point of the elements are very low
as as less energy required to break the Van der Waals forces between the molecules . Van
Assignment 1
11053457
Part b)
From the graph we can conclude that there is a direct relationship between the number of
carbon atoms, and the melting and boiling points of alkanes. As the boiling point increases
the number of carbon atoms also increases as a result of the increased intermolecular
forces. The van der Waal’s forces are greater in a larger in a larger molecule as the surface
area is higher thus there is greater chance of interconnections between the molecules.
The van der Waal’s forces is also greater due to the lengthy of the chain; as there is a
greater number of electrons present and the molecular mass being higher there is a greater
chance of interactions between the molecules. As a result more energy is required to break
the forces between the chains. On the other hand this trend does not appear as a smoothly
in the melting point as there is a difference between the odd and even numbered carbon
chains. The odd numbered carbon chains cannot pack together tightly in the solid phase
thus the separation of the chains are much easier and require less energy resulting in a
lower melting and boiling points. However the even numbered carbon chains can pack
together in the solid phase thus more energy is required separate the chains.
There is also a direct relationship between the number of carbon atoms and the melting and
the boiling points of the alcohol as a result of the increased Van der Waals’ forces. However
the boiling and melting points of alcohol are much greater than the alkanes even though their
number of carbon atoms are the same. This is a result of the OH group in the alcohols which
enables the formation of hydrogen bonds.Hydrogen bonds are much more stronger than der
Waals’ forces acting on them as well as hydrogen bonds.
Part c)
In an alcohol there are two parts: hydrophilic head and hydrophobic tail. Methanol, ethanol
and Propanol are Infinitely soluble in water due to the presence of OH group.
Hydrogen bonds can be formed between the alcohol and water molecules and the length of
the carbon chains is not long enough thus the Van de Waals’ forces between the chains will
not be strong enough to affect the solubility of the alcohol. However as the number of the
carbon atoms in the chain increases the solubility decreases as the Van der Waals’ forces
are stronger thus preventing the solubility.
Part d)
The elements in the graph goes across Period 3. Group 1-3 elements: Sodium, magnesium
and aluminium are the metals and they from metallic bonding by the attraction between
positive metal ions and delocalised electrons Sodium +1 Magnesium +2 and aluminium +3
shows that there is an increase in the positivity which results in the number of delocalised
electrons to increase thus the strength of the metallic bonding will be greater As a result of
the strong metallic bonding the boiling and the melting point increases
Group 4 element: silicon is a metalloid. It has giant covalent bonding and has giant lattice
structure similar to diamond thus the boiling and the melting point of silicon is higher as the
held together by strong covalent bonds. Thus more energy is required to break to bonds.
Group 0 5-8 elements: phosphorus, sulfur, chlorine and argon are all non-metals. The
elements are small ams separate molecules and exist as simple molecules with strong
covalent bonds between the atoms except Argon.Argon exist as separate atoms as it is a
noble gas and the outermost shell is full thus does not gain or lose electrons and as a result
in unreactive. The boiling and melting point of the melting point of the elements are very low
as as less energy required to break the Van der Waals forces between the molecules . Van
