Learning objective Key vocabulary Possible models and representations Possible misconceptions 8Cm.01 Describe the
Rutherford model of the structure of an atom.
Positive charge, negative charge, nucleus, atom, electron, proton, neutron, atomic model
The teaching of this objective will introduce learners
to the Rutherford model of the atom. Learners may think that atoms can be seen with a microscope; they often have difficulty appreciating just how small subatomic particles are. They could consider how small atoms must be given that, roughly, 500,000,000,000,000,000,000,000 atoms fit into a teaspoon.
Learners may not realise how much empty space there is in an atom. Use the analogy of a football stadium: if a tennis ball in the centre of the pitch represents the nucleus then the nearest electron is on the farthest row of seats and between them there is empty space.
Learners may think that only one model of the atom is correct. Emphasise that the Rutherford model can help our thinking but it has weaknesses and there may be better models.
8Cm.02 Know that electrons have negative charge, protons have positive charge and neutrons have no charge.
Proton, electron, neutron, charge, atom, positive, negative
Learners can construct a representation of an atom by using objects (e.g. round discs, blank playing cards) to represent protons, neutrons and
electrons. Ensure the objects are labelled with the respective charges.
Learners may confuse the term ‘charge’ with the idea of charging a battery. Take time to ensure that learners are clear about the distinction between these uses of the word.
8Cm.03 Know that the electrostatic attraction between positive and negative charge is what holds together individual atoms.
Electrostatic attraction, repulsion, charge, positive, negative, proton, neutron, electron, nucleus, atoms
Learners can take on the role of the protons and electrons and roleplay the electrostatic attractions between them; showing how the structure of an atom remains stable through this interaction.
The term ‘attraction’ might imply a choice. Be careful with your choice of language to ensure learners are aware that the attraction between positive and negative charges is simply one of their properties.
Some learners may think that the presence of only protons in the nucleus should cause repulsion. If this is raised by learners, it could be helpful to introduce the idea that nuclear forces hold the nucleus together.
Learners may think that the main attraction in an atom is between protons and electrons. Emphasise with learners that the attraction is between negative electrons and the positive nucleus (as a single
charge) rather than individual protons.
8Cc.03 Describe the reactivity of metals (limited to sodium, potassium, calcium, magnesium, zinc, iron, copper, gold and silver) with oxygen, water and dilute acids.
Metals, sodium, potassium, calcium, magnesium, zinc, iron, copper, gold, silver, oxygen, hydrochloric acid, chloride, sulfuric acid, sulfate, dilute,
concentrated, reaction, reactivity, series, hydrogen, metal salt, metal hydroxide, metal oxide, property/properties
Learners could role-play reactivity. A learner is designated as oxygen. Other learners are then designated as different metals. Each learners representing a metal is given a number
(representing their reactivity) The ‘oxygen’ stands next to the metal representing the lowest reactivity and then when another ‘metal’ of a higher reactivity is nearby the new ‘metal’ takes the ‘oxygen’ away.
This role-play can be carried out in a range of situations and with different elements.
Learners may think that different metals could
‘want’ to react whereas their reactivity is one of their properties. Careful use of language may be
necessary here to avoid this.
8Cc.01 Use word equations to describe reactions.
Reactant, product,
reaction, word equation Word equations are used to represent the
phenomenon of reactants reacting to form products. Learners may have difficulty with what the names of chemicals mean (e.g. ‘sulfuric acid’ is not made of
‘sulfuric’ and ‘acid’, ‘hydrochloric acid’ is not made of ‘hydrochloric’ and ‘acid’). Take the time to explain the conventions for naming chemicals.
8Cc.04 Know that reactions do not always lead to a single pure product and that
sometimes a reaction will produce an impure mixture of products.
Reaction, pure, impure,
mixture, reactant, product Coloured discs can be used to represent the atoms within reactants. Show learners that the ‘atoms’ can be combined in multiple ways and explain that some reactions (e.g. the incomplete combustion of carbon) create an impure mixture of products.
Learners may think that carbon dioxide is two products because there are two separate words.
Using a diagram demonstrate that carbon dioxide is a substance made from carbon and two oxygen atoms.
8Cc.06 Understand that some substances are generally unreactive and can be described as inert.
Unreactive, inert, helium, argon, gold, platinum, element, compound, molecule, atom
Inert substances could be represented in role play
by people who don’t interact with objects. Learners may think that all chemicals can be burned. Explain that some elements (e.g. helium, argon) do not form any compounds.
Learners may have heard of microplastics and think that they are different in chemical composition to plastic that they can see (e.g. plastic bottles).
Explain that microplastics are just small pieces of plastic.