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Chemistry 3.4 Describe properties of particles and thermochemical principles

Achievement criteria

The level of achievement that you will reach is decided by the way you answer each question about the properties of particles and thermochemical principles. The key words are describe, explain and apply, and discuss.

Achievement

• Describe properties of particles and thermochemical principles.

  This involves identifying, naming, defining, drawing, giving features of, outlining, and/or carrying out simple calculations.

  Make sure you can:

• write electron configurations (using s p d notation)
• calculate the correct number of valence electrons required in Lewis diagrams and use to identify the shapes of molecules and ions
• recognise ions that are isoelectronic
• recall trends in atomic size and ionisation energy and electronegativity, and be able to compare atomic and ionic radii
• understand ionisation energy and be able to determine trends of ionisation energy in elements
• distinguish between intermolecular and intramolecular bonding and the role of hydrogen bonding as an intermolecular force
• carry out simple calculations such as the conversion between mass and moles of a substance, and determine the enthalpy change for different amounts of a reactant
• understand how to use bond enthalpies or heats of formation to determine the enthalpy change, ΔrH, for a reaction
• relate the melting point of a substance to the intermolecular forces between its molecules, and recall the difference between breaking intermolecular, as opposed to intramolecular, bonds
• write balanced equations for chemical reactions or for ΔrH
• recognise transition metal properties and relate these to transition metal electron configurations.

Achievement with Merit

• Explain and apply properties of particles and thermochemical principles.

  This involves describing as well as justifying, clarifying, giving reasons for, giving an account of, making links, and/or carrying out calculations.

  Make sure you can:

• meet the criteria for Achievement
• understand and discuss the sizes of ions
• predict polarity and shape of a molecule using the relative electronegativity of named atoms, and apply the effect of repulsion between regions of electron density around the central atom
• demonstrate an understanding of the link between the numbers of electron shells in an atom or ion and its atomic radius and ionisation energy
• explain the properties and bonding of transition metals with reference to the electron configuration of these elements
• apply Hess’s Law to a given set of chemical equations
• use the correct working and procedures to solve a ΔH problem and understand the sign of the resulting answer.

Achievement with Excellence

• Discuss properties of particles and thermochemical principles.

  This involves evaluating, reviewing, analysing, interpreting, relating, comparing, and contrasting/or calculating.

  Make sure you can:

• meet the criteria for Merit
• analyse data and use chemical knowledge to predict trends in substances;
• apply thermochemical principles to particular contexts, and write a balanced equation for the reaction associated with the value of a particular Δ_fH
• have a higher level of understanding of intermolecular bonding, and be able to discuss relative strengths of attractions between particles; explain hydrogen bonding, and relate these to given enthalpy values
• write and use equations to calculate enthalpy changes
• include states or phases of elements or molecules in equations.

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