• representing chemical reactions using formulae and using equations
• combustion, thermal decomposition, oxidation and displacement reactions
• what catalysts do.
• energy changes on changes of state (qualitative)
• exothermic and endothermic chemical reactions (qualitative).
• properties of ceramics, polymers and composites (qualitative).
Earth and atmosphere
• the composition of the atmosphere
Calculation of fuel uses and costs in the domestic context
• comparing energy values of different foods (from labels) (kJ)
• comparing power ratings of appliances in watts (W, kW)
• comparing amounts of energy transferred (J, kJ, kW hour)
• domestic fuel bills, fuel use and costs
• fuels and energy resources.
Energy changes and transfers
• simple machines give bigger force but at the expense of smaller movement (and vice versa): product of force and displacement unchanged
• heating and thermal equilibrium: temperature difference between two objects leading to energy transfer from the hotter to the cooler one, through contact (conduction) or radiation; such transfers tending to reduce the temperature difference: use of insulators
• other processes that involve energy transfer: changing motion, dropping an object, completing an electrical circuit, stretching a spring, metabolism of food, burning fuels.
Changes in systems
• energy as a quantity that can be quantified and calculated; the total energy has the same value before and after a change
• comparing the starting with the final conditions of a system and describing increases and decreases in the amounts of energy associated with movements, temperatures, changes in positions in a field, in elastic distortions and in chemical compositions
• using physical processes and mechanisms, rather than energy, to explain the intermediate steps that bring about such changes.
Motion and forces
• speed and the quantitative relationship between average speed, distance and time (speed = distance ÷ time)
• the representation of a journey on a distance-time graph
• relative motion: trains and cars passing one another.
• forces as pushes or pulls, arising from the interaction between two objects
• using force arrows in diagrams, adding forces in one dimension, balanced and unbalanced forces
• moment as the turning effect of a force
• forces: associated with deforming objects; stretching and squashing – springs; with rubbing and friction between surfaces, with pushing things out of the way; resistance to motion of air and water
• forces measured in newtons, measurements of stretch or compression as force is changed
• force-extension linear relation; Hooke’s Law as a special case
• work done and energy changes on deformation
• non-contact forces: gravity forces acting at a distance on Earth and in space, forces between magnets and forces due to static electricity.
Pressure in fluids
• atmospheric pressure, decreases with increase of height as weight of air above decreases with height
• pressure in liquids, increasing with depth; upthrust effects, floating and sinking
• pressure measured by ratio of force over area – acting normal to any surface.
• opposing forces and equilibrium: weight held by stretched spring or supported on a compressed surface.
Forces and motion
• forces being needed to cause objects to stop or start moving, or to change their speed or direction of motion (qualitative only)
• change depending on direction of force and its size.
Energy and waves
• pressure waves transferring energy; use for cleaning and physiotherapy by ultra-sound; waves transferring information for conversion to electrical signals by microphone.
• the similarities and differences between light waves and waves in matter
• light waves travelling through a vacuum; speed of light
• the transmission of light through materials: absorption, diffuse scattering and specular reflection at a surface
Electricity and electromagnetism
• electric current, measured in amperes, in circuits, series and parallel circuits, currents add where branches meet and current as flow of charge
• potential difference, measured in volts, battery and bulb ratings; resistance, measured in ohms, as the ratio of potential difference (p.d.) to current
• differences in resistance between conducting and insulating components (quantitative).
• separation of positive or negative charges when objects are rubbed together: transfer of electrons, forces between charged objects
• the idea of electric field, forces acting across the space between objects not in contact.
• magnetic poles, attraction and repulsion
• magnetic fields by plotting with compass, representation by field lines
• Earth’s magnetism, compass and navigation
• the magnetic effect of a current, electromagnets, D.C. motors (principles only).
• conservation of material and of mass, and reversibility, in melting, freezing, evaporation, sublimation, condensation, dissolving
• similarities and differences, including density differences, between solids, liquids and gases
• Brownian motion in gases
• diffusion in liquids and gases driven by differences in concentration
• the difference between chemical and physical changes.
• the differences in arrangements, in motion and in closeness of particles explaining changes of state, shape and density, the anomaly of ice-water transition
• atoms and molecules as particles.
Energy in matter
• changes with temperature in motion and spacing of particles
• internal energy stored in materials.
• gravity force, weight = mass x gravitational field strength (g), on Earth g=10 N/kg, different on other planets and stars; gravity forces between Earth and Moon, and between Earth and Sun (qualitative only)
• our Sun as a star, other stars in our galaxy, other galaxies
• the seasons and the Earth’s tilt, day length at different times of year, in different hemispheres
• the light year as a unit of astronomical distance.