Topic 7: Intermolecular Forces

Understand the nature of the following intermolecular forces: i London forces (instantaneous dipole-induced dipole) ii permanent dipole-permanent dipole interactions iii hydrogen bonds.

Use —the nature of the following intermolecular forces: i london forces (instantaneous dipole-induced dipole) ii permanent to connect the rule to the data and decision in the question.

This matters because —the nature of the following intermolecular forces: i london forces (instantaneous dipole-induced dipole) ii permanent determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —the nature of the following intermolecular forces: i london forces (instantaneous dipole-induced dipole) ii permanent to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —The nature of the following intermolecular forces: i London forces (instantaneous dipole-induced dipole) ii permanent is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Understand the interactions in molecules, such as H2O, liquid NH3 and liquid HF, which give rise to hydrogen bonding.

Use —the interactions in molecules, such as h2o, liquid nh3 and liquid hf, which give rise to hydrogen bonding to connect the rule to the data and decision in the question.

This matters because —the interactions in molecules, such as h2o, liquid nh3 and liquid hf, which give rise to hydrogen bonding determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —the interactions in molecules, such as h2o, liquid nh3 and liquid hf, which give rise to hydrogen bonding to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —The interactions in molecules, such as H2O, liquid NH3 and liquid HF, which give rise to hydrogen bonding is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Understand the following anomalous properties of water resulting from hydrogen bonding: i its high melting and boiling temperature when compared with similar molecules ii the density of ice compared to that of water.

Use —the following anomalous properties of water resulting from hydrogen bonding: i its high melting and boiling temperature when to connect the rule to the data and decision in the question.

This matters because —the following anomalous properties of water resulting from hydrogen bonding: i its high melting and boiling temperature when determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —the following anomalous properties of water resulting from hydrogen bonding: i its high melting and boiling temperature when to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —The following anomalous properties of water resulting from hydrogen bonding: i its high melting and boiling temperature when is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Be able to predict the presence of hydrogen bonding in molecules analogous to those mentioned in 7.2.

Use —predict the presence of hydrogen bonding in molecules analogous to those mentioned in 7.2 to connect the rule to the data and decision in the question.

This matters because —predict the presence of hydrogen bonding in molecules analogous to those mentioned in 7.2 determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —predict the presence of hydrogen bonding in molecules analogous to those mentioned in 7.2 to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Predict the presence of hydrogen bonding in molecules analogous to those mentioned in 7.2 is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Understand, in terms of intermolecular forces, physical properties shown by substances, including: i the trends in boiling temperatures of alkanes with increasing chain length ii the effect of branching in the carbon chain on the boiling temperatures of alkanes iii the relatively low volatility (higher boiling temperatures) of alcohols compared to alkanes with a similar number of electrons iv the trends in boiling temperatures of the hydrogen halides HF to HI.

Use —understand, in terms of intermolecular forces, physical properties shown by substances to connect the rule to the data and decision in the question.

This matters because —understand, in terms of intermolecular forces, physical properties shown by substances determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —understand, in terms of intermolecular forces, physical properties shown by substances to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Understand, in terms of intermolecular forces, physical properties shown by substances is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Understand factors that influence the choice of solvents, including: i water, to dissolve some ionic compounds, in terms of the hydration of the ions ii water, to dissolve simple alcohols, in terms of hydrogen bonding iii water, as a poor solvent for compounds (to include polar molecules such as halogenoalkane), in terms of inability to form hydrogen bonds iv non-aqueous solvents, for compounds that have similar intermolecular forces to those in the solvent.

Use —factors that influence the choice of solvents to connect the rule to the data and decision in the question.

This matters because —factors that influence the choice of solvents determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —factors that influence the choice of solvents to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Factors that influence the choice of solvents is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.