Topic 3: Bonding and Structure

Know and be able to interpret evidence for the existence of ions, limited to physical properties of ionic compounds, electron density maps and the migration of ions.

Use —interpret evidence for the existence of ions to connect the rule to the data and decision in the question.

This matters because —interpret evidence for the existence of ions determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —interpret evidence for the existence of ions to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Interpret evidence for the existence of ions is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Be able to describe the formation of ions in terms of loss or gain of electrons.

Use —the formation of ions in terms of loss or gain of electrons to connect the rule to the data and decision in the question.

This matters because —the formation of ions in terms of loss or gain of electrons determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —the formation of ions in terms of loss or gain of electrons to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —The formation of ions in terms of loss or gain of electrons is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Be able to draw dot-and-cross diagrams to show electrons in cations and anions.

Use —draw dot-and-cross diagrams to show electrons in cations and anions to connect the rule to the data and decision in the question.

This matters because —draw dot-and-cross diagrams to show electrons in cations and anions determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —draw dot-and-cross diagrams to show electrons in cations and anions to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Draw dot-and-cross diagrams to show electrons in cations and anions is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Be able to describe ionic crystals as giant lattices of ions.

Use —ionic crystals as giant lattices of ions to connect the rule to the data and decision in the question.

This matters because —ionic crystals as giant lattices of ions determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —ionic crystals as giant lattices of ions to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Ionic crystals as giant lattices of ions is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Know that ionic bonding is the result of strong net electrostatic attraction between ions.

Use —ionic bonding is the result of strong net electrostatic attraction between ions to connect the rule to the data and decision in the question.

This matters because —ionic bonding is the result of strong net electrostatic attraction between ions determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —ionic bonding is the result of strong net electrostatic attraction between ions to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Ionic bonding is the result of strong net electrostatic attraction between ions is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Understand the effects of ionic radius and ionic charge on the strength of ionic bonding.

Use —the effects of ionic radius and ionic charge on the strength of ionic bonding to connect the rule to the data and decision in the question.

This matters because —the effects of ionic radius and ionic charge on the strength of ionic bonding determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —the effects of ionic radius and ionic charge on the strength of ionic bonding to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —The effects of ionic radius and ionic charge on the strength of ionic bonding is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Understand reasons for the trends in ionic radii down a group in the Periodic Table, and for a set of isoelectronic ions, including N3− to Al3+.

Use —reasons for the trends in ionic radii down a group in the periodic table, and for a set of isoelectronic ions to connect the rule to the data and decision in the question.

This matters because —reasons for the trends in ionic radii down a group in the periodic table, and for a set of isoelectronic ions determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —reasons for the trends in ionic radii down a group in the periodic table, and for a set of isoelectronic ions to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Reasons for the trends in ionic radii down a group in the Periodic Table, and for a set of isoelectronic ions is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Understand the meaning of the term ‘polarisation’ as applied to ions.

Use —the meaning of the term ‘polarisation’ as applied to ions to connect the rule to the data and decision in the question.

This matters because —the meaning of the term ‘polarisation’ as applied to ions determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —the meaning of the term ‘polarisation’ as applied to ions to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —The meaning of the term ‘polarisation’ as applied to ions is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Understand that the polarising power of a cation depends on its radius and charge, and the polarisability of an anion also depends on its radius and charge.

Use —the polarising power of a cation depends on its radius and charge, and the polarisability of an anion also depends on its to connect the rule to the data and decision in the question.

This matters because —the polarising power of a cation depends on its radius and charge, and the polarisability of an anion also depends on its determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —the polarising power of a cation depends on its radius and charge, and the polarisability of an anion also depends on its to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —The polarising power of a cation depends on its radius and charge, and the polarisability of an anion also depends on its is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Understand that covalent bonding is the strong electrostatic attraction between two nuclei and the shared pair of electrons between them, based on the evidence: i the physical properties of giant atomic structures ii electron density maps for simple molecules.

Use —covalent bonding is the strong electrostatic attraction between two nuclei and the shared pair of electrons between them to connect the rule to the data and decision in the question.

This matters because —covalent bonding is the strong electrostatic attraction between two nuclei and the shared pair of electrons between them determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —covalent bonding is the strong electrostatic attraction between two nuclei and the shared pair of electrons between them to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Covalent bonding is the strong electrostatic attraction between two nuclei and the shared pair of electrons between them is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Be able to draw dot-and-cross diagrams to show electrons in covalent substances, including: i molecules with single, double and triple bonds ii species with dative covalent (coordinate) bonds, including Al2Cl6 and the ammonium ion.

Use —draw dot-and-cross diagrams to show electrons in covalent substances to connect the rule to the data and decision in the question.

This matters because —draw dot-and-cross diagrams to show electrons in covalent substances determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —draw dot-and-cross diagrams to show electrons in covalent substances to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Draw dot-and-cross diagrams to show electrons in covalent substances is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Be able to describe the different structures formed by giant lattices of carbon atoms, including graphite, diamond and graphene, and discuss the applications of each.

Use —the different structures formed by giant lattices of carbon atoms to connect the rule to the data and decision in the question.

This matters because —the different structures formed by giant lattices of carbon atoms determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —the different structures formed by giant lattices of carbon atoms to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —The different structures formed by giant lattices of carbon atoms is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Understand the meaning of the term ‘electronegativity’ as applied to atoms in a covalent bond.

Use —the meaning of the term ‘electronegativity’ as applied to atoms in a covalent bond to connect the rule to the data and decision in the question.

This matters because —the meaning of the term ‘electronegativity’ as applied to atoms in a covalent bond determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —the meaning of the term ‘electronegativity’ as applied to atoms in a covalent bond to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —The meaning of the term ‘electronegativity’ as applied to atoms in a covalent bond is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Know that ionic and covalent bonding are the extremes of a continuum of bonding type and be able to explain this in terms of electronegativity differences, leading to bond polarity in bonds and molecules, and to ionic bonding if the electronegativity is large enough.

Use —ionic and covalent bonding are the extremes of a continuum of bonding type to connect the rule to the data and decision in the question.

This matters because —ionic and covalent bonding are the extremes of a continuum of bonding type determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —ionic and covalent bonding are the extremes of a continuum of bonding type to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Ionic and covalent bonding are the extremes of a continuum of bonding type is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Be able to distinguish between polar bonds and polar molecules and predict whether or not a given molecule is likely to be polar.

Use —distinguish between polar bonds and polar molecules and predict whether or not a given molecule is likely to be polar to connect the rule to the data and decision in the question.

This matters because —distinguish between polar bonds and polar molecules and predict whether or not a given molecule is likely to be polar determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —distinguish between polar bonds and polar molecules and predict whether or not a given molecule is likely to be polar to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Distinguish between polar bonds and polar molecules and predict whether or not a given molecule is likely to be polar is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Understand the principles of the electron-pair repulsion theory, used to interpret and predict the shapes of simple molecules and ions.

Use —the principles of the electron-pair repulsion theory, used to interpret and predict the shapes of simple molecules and ions to connect the rule to the data and decision in the question.

This matters because —the principles of the electron-pair repulsion theory, used to interpret and predict the shapes of simple molecules and ions determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —the principles of the electron-pair repulsion theory, used to interpret and predict the shapes of simple molecules and ions to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —The principles of the electron-pair repulsion theory, used to interpret and predict the shapes of simple molecules and ions is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Understand the terms ‘bond length’ and ‘bond angle’.

Use —the terms ‘bond length’ and ‘bond angle’ to connect the rule to the data and decision in the question.

This matters because —the terms ‘bond length’ and ‘bond angle’ determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —the terms ‘bond length’ and ‘bond angle’ to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —The terms ‘bond length’ and ‘bond angle’ is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Know and explain the shapes of, and bond angles in, BeCl2, BCl3, CH4, NH3, NH4+, H2O, CO2, gaseous PCl5, SF6 and C2H4.

Use —and explain the shapes of, and bond angles in, becl2, bcl3, ch4, nh3, nh4+, h2o, co2, gaseous pcl5, sf6 and c2h4 to connect the rule to the data and decision in the question.

This matters because —and explain the shapes of, and bond angles in, becl2, bcl3, ch4, nh3, nh4+, h2o, co2, gaseous pcl5, sf6 and c2h4 determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —and explain the shapes of, and bond angles in, becl2, bcl3, ch4, nh3, nh4+, h2o, co2, gaseous pcl5, sf6 and c2h4 to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —And explain the shapes of, and bond angles in, BeCl2, BCl3, CH4, NH3, NH4+, H2O, CO2, gaseous PCl5, SF6 and C2H4 is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Be able to apply the electron-pair repulsion theory to predict the shapes of, and bond angles in, molecules and ions analogous to those in 3.18 3D: Metallic bonding Students will be assessed on their ability to:.

Use —apply the electron-pair repulsion theory to predict the shapes of, and bond angles in, molecules and ions analogous to those to connect the rule to the data and decision in the question.

This matters because —apply the electron-pair repulsion theory to predict the shapes of, and bond angles in, molecules and ions analogous to those determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —apply the electron-pair repulsion theory to predict the shapes of, and bond angles in, molecules and ions analogous to those to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Apply the electron-pair repulsion theory to predict the shapes of, and bond angles in, molecules and ions analogous to those is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Understand that metals consist of giant lattices of metal ions in a sea of delocalised electrons.

Use —metals consist of giant lattices of metal ions in a sea of delocalised electrons to connect the rule to the data and decision in the question.

This matters because —metals consist of giant lattices of metal ions in a sea of delocalised electrons determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —metals consist of giant lattices of metal ions in a sea of delocalised electrons to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Metals consist of giant lattices of metal ions in a sea of delocalised electrons is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Know that metallic bonding is the strong electrostatic attraction between metal ions and the delocalised electrons.

Use —metallic bonding is the strong electrostatic attraction between metal ions and the delocalised electrons to connect the rule to the data and decision in the question.

This matters because —metallic bonding is the strong electrostatic attraction between metal ions and the delocalised electrons determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —metallic bonding is the strong electrostatic attraction between metal ions and the delocalised electrons to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Metallic bonding is the strong electrostatic attraction between metal ions and the delocalised electrons is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Be able to use the models in 3.20 and 3.21 to interpret simple properties of metals, including electrical conductivity and high melting temperature.

Use —the models in 3.20 and 3.21 to interpret simple properties of metals to connect the rule to the data and decision in the question.

This matters because —the models in 3.20 and 3.21 to interpret simple properties of metals determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —the models in 3.20 and 3.21 to interpret simple properties of metals to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —The models in 3.20 and 3.21 to interpret simple properties of metals is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.