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| Elements, molecules, and compounds - All matter is composed of atoms.
- The particles that make up substances are composed of atoms.
- The different types of atoms are known as elements.
- Each element has an atomic symbol (e.g. H, O, Ag).
- Compounds are substances made of more than one element (e.g. water, carbon dioxide).
- Chemical symbols and formulas represent the types and numbers of atoms in substances. Common substances and their chemical formulas: O2, H2, H2O, CO2, CO, HCl, NaCl, Fe2O3.
- Molecules are particles made of two or more atoms bonded together (e.g. water, oxygen, nitrogen, carbon dioxide) and may be compounds.
- Substances may be pure or mixtures:
- a substance is pure if it includes only one type of atom, molecule, or compound
- a substance is a mixture if it includes more than one type of atom, molecule, or compound.
- Jöns Jakob Berzelius (1779–1848) introduced chemical symbols and determined atomic weights, helping standardise chemical notation and atomic theory.
Periodic table - Elements are arranged in the periodic table based on their physical and chemical properties.
- The periodic table is organised into vertical columns called groups and horizontal rows called periods.
- Elements can be classified as either metals or non-metals:
- metals have the physical properties of higher melting points, lustre, and higher electrical and thermal conductivity
- non-metals have the physical properties of lower boiling points (most are gases at room temperature) and lower electrical and thermal conductivity.
- Elements in the same group have similar chemical properties (reactivity, metallic characteristics).
- The periodic table can be used to predict how elements will react (group 1, 2, 17, 18):
- group 1 and 2 are metals, and groups 17 and 18 are non-metals (group 17 is halogens, group 18 is noble gases)
- reactivity increases down groups 1 and 2
- reactivity decreases down group 17
- group 18 is non-reactive.
- Dmitri Mendeleev (1834–1907) created the periodic table of elements and predicted properties of undiscovered elements, revolutionising chemistry.
| Atomic theory - The Bohr model describes an atom as having a nucleus made of subatomic components (protons and neutrons), surrounded by shells of electrons.
- The Bohr model’s development from Rutherford’s discovery of the nucleus demonstrates that improved scientific understanding builds on earlier evidence and ideas.
- Protons, neutrons, and electrons have different charges and relative masses:
- protons and neutrons have approximately the same mass
- the element number of an element is equal to the number of protons, and elements on the periodic table are sorted by this number
- the mass number of an element is equal to the sum of neutrons and protons
- electrons have relatively no mass
- protons have a single positive charge, and electrons have a single negative charge
- neutrons do not have a charge.
- The number of protons in an atom determines which element it is.
- The electronic structure of an atom determines how it bonds and reacts with other atoms:
- atoms in the first three periods of the periodic table have electron configurations that follow the pattern 2,8,8
- the valence shell is the outermost electron shell of an atom; electrons in this shell are called valence electrons and are involved in chemical bonding
- compounds form when atoms transfer or share electrons to obtain a full valence shell (the octet rule for elements in periods 1–3 means the valence shell is full when it has 8 total valence electrons, except for hydrogen and helium, which can have 2 total valence electrons)
- ions form when metals transfer electrons to non-metals, resulting in positively charged metal cations and negatively charged non-metal anions
- oppositely charged ions form ionic bonds through electrostatic attraction and often result in the formation of crystals
- ionic substances are commonly referred to as salts
- some ions are polyatomic, including carbonate (CO32−) and nitrate (NO3−)
- the chemical formula for an ionic substance is balanced to cancel out the total charge
- molecules form when non-metals share electrons to create bonding electron pairs.
- J.J. Thomson (1856–1940) discovered the electron, revealing the existence of subatomic particles.
- Ernest Rutherford (1871–1937) proposed the nuclear model of the atom, identifying a dense central nucleus through gold foil experiments.
| Elements, molecules, and compounds - Providing examples of pure substances in everyday life
- Distinguishing between pure substances and compounds from a chemical formula
- Interpreting provided chemical formulas to identify the number of atoms of a given element in a compound
Periodic table - Using the periodic table to locate and classify metallic and non-metallic elements
- Predicting the reactivity of group 1–2 metals and group 17–18 non-metals using the periodic table
- Finding the atomic symbol of an element using the periodic table
| Atomic theory - Representing elements 1–20 using a diagram of the Bohr model, labelling subatomic particles
- Identifying the total charge on atoms given a number of protons, neutrons, and electrons
- Identifying the charge of ions produced by elements in the first three periods with full valence shells
- Balancing the chemical formula of salts formed from ions between elements in the first three periods
- Naming simple salts formed between a single metal and non-metal in the first three periods
- Determining molecular formulas for simple molecules formed with elements in the first three periods, based on their valence (e.g. H2O, CO2, NH3, HCl, CH4)
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| Chemical reactions - Chemical reactions create new substances by rearranging particles and may be observed as bubbles (gases), precipitates (solids), heat change (hotter or colder), or colour changes.
- Reactants are the substances present at the start of a chemical reaction, and products are the new substances formed during the reaction.
- Chemical reactions involve energy changes, which can be observed as thermal energy transfers to (exothermic) or from (endothermic) the surroundings.
- Chemical reactions, including combustion and acid-base reactions, play key roles in both living systems (e.g. digestion) and non-living systems (e.g. engines).
- Chemical reactions can be represented using word equations (e.g. sodium hydroxide + hydrochloric acid → sodium chloride + water).
- Jean Beguin (1550–1620) published the first recorded chemical equation, helping formalise chemical reactions.
| Reactions with acids and bases - The pH scale can be used to measure acidity, and this can be identified by the use of chemical indicators.
- Many acids and bases are corrosive materials.
- Bases that are soluble in water are known as alkalis.
- Acids react with bases to produce water and salts in neutralisation reactions.
- Acids react with metals to produce hydrogen gas and salts.
- Acids react with metal carbonates to produce carbon dioxide, water, and salts.
- There are tests to determine which gases have been produced in a reaction (hydrogen, carbon dioxide).
- Common acids and bases: hydrochloric acid (HCl), sulfuric acid (H2SO4), nitric acid (HNO3), sodium hydroxide (NaOH), potassium hydroxide (KOH), ammonia (NH3).
- Chemical reactions can be represented using balanced chemical equations.
- Søren Peter Lauritz Sørensen (1868–1939) introduced the pH scale, quantifying hydrogen ion concentration in solutions.
Combustion - Combustion is a chemical reaction between a fuel and an oxidising agent.
- Oxygen is a common oxidising agent on earth.
- Combustion is a process in which energy is transferred, primarily as heat and light.
- Combustion of hydrocarbons with oxygen produces water and carbon dioxide.
- Combustion of hydrogen with oxygen produces water.
- Common hydrocarbons: methane (CH4), octane (C8H10), ethanol (C2H6O).
- John Warnatz (1944–2007) studied high-temperature hydrocarbon reaction mechanisms, advancing combustion kinetics.
Displacement - A more reactive metal can replace a less reactive metal in a salt solution (e.g. iron placed in a copper sulphate solution will take the place of the copper). This is called single displacement.
- When salt solutions are mixed, insoluble combinations of ions may form a precipitate, identified as a solid that may settle to the bottom. This is called a double displacement or precipitation reaction.
- The solubility of ion combinations can be determined using a solubility table, and this can be used to predict precipitation reactions.
- Common precipitates: silver chloride (AgCl), barium sulfate (BaSO4), calcium carbonate (CaCO3).
- John Daniell (1790–1845) invented an early battery in 1836 that relied on a single displacement reaction between zinc and copper sulfate, providing a clear and practical example of the principle.
Rate of reaction - The rate of a chemical reaction can be increased with temperature, concentration, surface area, and catalysis.
| Chemical reactions - Observing common chemical reactions and providing evidence that a chemical reaction has taken place
- Using word equations to describe basic chemical reactions
| Reactions with acids and bases - Representing the reaction of acids with bases, metals, and metal carbonates using word and balanced chemical equations when chemical formulas are provided
- Making scientific observations and predictions involving acid reactions
- Classifying solutions using the pH scale
- Manipulating the pH of a solution by adding an acid or a base
- Planning and conducting identification tests for hydrogen and carbon dioxide gases
Combustion - Representing combustion of hydrogen and hydrocarbon fuels with oxygen in word and balanced chemical equations when chemical formulas are provided
- Making scientific observations and predictions involving combustion reactions
Displacement - Representing single and double displacement reactions in word and balanced chemical equations when chemical formulas are provided
- Making scientific observations and predictions involving displacement reactions
- Drawing conclusions about the relative reactivity of metals using the results of a series of single displacement reactions
- Determining the formula of precipitates from the formulas of the reactants and a solubility table
Rate of reaction - Making predictions and observations about the rate of a chemical reaction when adding a catalyst is added or when the concentration of a reactant, surface area, or temperature is changed
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Matter Interactions and Energy
| | Energy - Energy is a quantifiable property of a system that is conserved and can be calculated based on other measurable quantities, but it cannot be directly observed or measured.
- Work is done when a force causes an object to move in the direction of the force, resulting in a transfer of energy.
- Energy in a system may be associated with different properties, commonly described as kinetic or potential energy:
- kinetic energy is associated with motion, including the energy of moving objects and the random motion of particles in thermal energy
- potential energy is associated with the position or configuration of a system, including gravitational, elastic, and chemical energy.
- The law of conservation of energy states that energy cannot be created nor destroyed, but can be transferred between systems or transformed based on changes in motion, position, or configuration. In a closed system, the total energy remains constant.
- Energy is measured in the standard unit Joule (J).
- Energy diagrams are used to model the transfer and transformation of energy and to represent energy efficiency in a system:
- energy transfers and transformations are not 100% efficient. Some energy is always dispersed to the surroundings in forms that are not useable for the intended purpose. This dispersal can be observed as heat, light, sound, or movement.
- energy efficiency is the percentage of input energy that is usefully transferred or transformed for the intended purpose.
- the overall energy efficiency of a series of transfers or transformations can be calculated by multiplying the individual efficiencies (expressed as decimals).
- Changes in the natural and human world involve the transfer and transformation of energy:
- when food is digested, energy stored in chemical bonds is released and used to support the functions of organisms (see Year 8, Body Systems)
- photosynthesis involves a transformation of energy from sunlight into chemical energy stored in sugars (see Year 7, Body Systems).
- Combustion of fuels involves chemical reactions that release energy stored in molecular bonds. This energy increases the thermal energy of the system and can result in light emission:
- in combustion engines (e.g. cars), the increase in thermal energy causes gases to expand rapidly, generating pressure that drives mechanical components (e.g. pistons), resulting in motion.
- in rockets, combustion increases the temperature and pressure of gases, which are expelled at high velocity through a nozzle. the resulting thrust is produced by the reaction force, in accordance with Newton’s third law.
- Julius Robert von Mayer (1814–1878) established the mechanical equivalent of heat, linking energy conservation to thermodynamics.
- James Prescott Joule (1818–1889) quantified the relationship between heat and mechanical work, contributing to the first law of thermodynamics.
- William Thomson (Lord Kelvin) (1824–1907) defined absolute temperature and helped formulate thermodynamic laws.
- William Pickering (1910–2004) was a New Zealand born rocket scientist who directed NASA’s Jet Propulsion Laboratory and contributed to the development of space exploration and satellite technology.
Waves - Waves are an oscillating disturbance in matter or a field (region of space) that transfers energy but not matter.
- Mechanical waves transfer energy through matter and include sound and water waves.
- Electromagnetic waves transfer energy through fields and include visible light; they can travel through a vacuum with a constant speed, the ‘speed of light’ (c).
- Waves can be transverse or longitudinal:
- transverse waves oscillate perpendicularly to the direction of travel
- longitudinal waves oscillate in the direction of the travel.
- Sound travels as a longitudinal mechanical wave:
- sound waves transfer kinetic (vibrational) energy
- sound is produced by and produces vibrations of matter
- sound is sensed when waves of sound cause sensors or ear drums to vibrate
- the range of sounds heard by animals varies
- sound travels more quickly through denser materials (e.g. faster through water than air)
- soundwaves are measured in hertz (Hz, frequency, pitch) and decibels (dB, amplitude, volume).
- Light travels as a transverse electromagnetic wave:
- when light interacts with matter, energy can be transferred (e.g. absorbed as heat)
- when light interacts with a surface it may be absorbed (and thus transferred or transformed), transmitted, or reflected
- when light is transmitted through the boundary of two different media (e.g. water, glass, air), it can be refracted, bending the path of light
- reflection can be specular, where light rays maintain parallel paths of travel, or diffuse, where light rays travel in different directions, also known as scattering
- electromagnetic waves, including light waves, are characterised by their wavelength (λ), which ranges from kilometres (radio) to picometers (gamma), and their frequency (Hz)
- there is an inverse relationship between wavelength and frequency
- the spectrum of light visible to most humans has wavelengths of approximately 400–700 nanometres (nm)
- the frequency of light waves determines their colour as perceived by humans (e.g. red has lower frequency and longer wavelength than violet, which has higher frequency and shorter wavelength)
- white light contains all visible wavelengths of light
- when white light is refracted through a prism, it disperses (splits) into its constituent wavelengths
- black is not a colour of light, but how we perceive an absence of light
- objects absorb some wavelengths of light and reflect others — the reflected wavelengths are perceived as the colour of the object
- transparent materials let light through. Coloured transparent materials transmit wavelengths that correspond to their perceived colour; other wavelengths are absorbed.
- Christiaan Huygens (1629–1695) proposed the wave theory of light, explaining reflection and refraction phenomena.
- James Clerk Maxwell (1831–1879) formulated electromagnetic wave theory, unifying electricity, magnetism, and light.
- Heinrich Hertz (1857–1894) provided experimental proof of electromagnetic waves, validating electromagnetic theory.
| | Energy - Applying the law of conservation of energy to account for transformations between energy forms within simple everyday closed systems (e.g. combustion engines, light bulbs, speakers, turbines), including:
- identifying energy transfers and transformations and representing them using simple energy flow diagrams
- identifying and calculating missing values in energy flow diagrams, restricted to joule measurements of energy
- calculating the energy efficiency of simple everyday systems when given the starting and final energy amounts in joules or the % efficiency of individual steps
- Investigating emerging energy production types and assessing their relevance to New Zealand
Waves - Observing and qualitatively comparing transverse and longitudinal mechanical waves
- Classifying everyday waves, including water waves, light and sound as mechanical/electromagnetic, transverse/longitudinal
- Measuring the frequency (Hz) and amplitude (dB) of pure tones and comparing their pitch and loudness with reference to these measurements
- Investigating the behaviour of light interacting with a range of surfaces and objects and making observations of reflection, scattering, absorption, transmittance, and refraction
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| The effect of forces - The action of forces on the movement of objects can be described using Newton’s Laws of Motion.
- Newton’s First Law of Motion:
- net force is the overall force acting on an object, after all the individual forces (including their directions) are combined
- when the net force on an object is zero (forces are balanced), the object stays at rest or continues to move at constant velocity in a straight line
- when the net force on an object is non-zero, the object’s motion changes. This can be a change in velocity or direction.
- objects resist changes in motion. This property is called inertia and depends on the object’s mass.
- Newton’s Second Law of Motion:
- more force causes more acceleration on the same mass, but more massive objects accelerate less when the same force is applied
- the relationship between force, mass, and acceleration is given by F = ma
- force is measured in newtons (N).
- Newton’s Third Law of Motion:
- forces are always paired as action and reaction force pairs
- every interaction between objects involves equal and opposite forces acting on each object.
- Friction opposes relative motion across surfaces and through fluids (e.g. air resistance and water resistance are types of friction) (see Year 5 and Year 7, Motion and Forces).
- Equal forces acting on the same rigid body (an object whose shape cannot change) in opposite directions will cancel out.
- Forces acting on a rigid body can be summarised in a free body diagram to determine net force.
- Velocity is the rate at which an object moves.
- Acceleration is the rate at which an object’s velocity changes.
- Motion can be represented using graphs that show changes in velocity or distance over time (see Year 8, Motion and Forces).
- Isaac Newton (1643–1727) developed the laws of motion and universal gravitation, forming the foundation of classical mechanics and celestial dynamics.
- Note: At this level, it is not necessary to break down a Newton into its base units (kg⋅m/s²).
Fluids and pressure (See Year 5 and Year 8, Motion and Forces) - Atmospheric pressure decreases with altitude because the weight of air above reduces as height increases.
- Pressure in liquids increases with depth due to the increasing weight of liquid above.
- Upthrust determines whether objects float or sink.
- Blaise Pascal (1623–1662) formulated Pascal’s principle of pressure and contributed to fluid mechanics and probability theory.
| | The effect of forces - Measuring and comparing forces in practical contexts
- Representing common forces (e.g. gravity, friction) using free body diagrams and identifying unbalanced forces acting on rigid bodies (e.g. the forces acting on a rocket)
- Calculating force, mass, or acceleration using the relationship (F = ma) and calculating net force using free body diagrams
- Predicting, observing, and measuring how resistance forces affect motion of objects (e.g. rockets, fish, swimmers, cars) in different environments (e.g. air, water, surfaces)
- Measuring and comparing an object’s average velocity and instantaneous velocity using motion graphs or data tables
- Identifying the independent, dependent, and control variables in a motion experiment, describing how these can be managed to ensure reliable results
Fluids and pressure - Linking water depth and altitude to pressure changes (e.g. a diver experiences greater pressure the deeper they go underwater, it becomes harder to breathe at higher altitudes)
- Using models or demonstrations to interpret how pressure in fluids changes with depth, including in natural systems (air pressure and altitude, sea pressure and depth)
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| Spheres of the Earth - The atmosphere is a layer of gas surrounding the Earth.
- The atmosphere is a mixture of gases (e.g. nitrogen, oxygen, argon, carbon dioxide, water vapour).
- The lithosphere is the rocky surface and interior of the Earth.
- The biosphere is all living organisms and recently living organisms on Earth.
- The hydrosphere is all water on the surface of earth.
- Tracking the cycling of matter and the transfer of energy shows how Earth’s spheres affect each other (e.g. water evaporates from the hydrosphere into the atmosphere and returns as precipitation).
- Solar radiation the Earth receives decreases with increasing latitude (e.g. more at the equator — latitude 0°, less at the poles — latitude 90°N and 90°S).
- Global ocean convection circulates water and stabilises the global climate.
- Matter cycles and energy transfers occur within and between Earth’s spheres through global systems, such as the water and carbon cycle.
- Eduard Suess (1831–1914) introduced the terms hydrosphere, lithosphere, and biosphere in 1875, helping define Earth’s major interacting systems in geology.
| Carbon cycle - Carbon cycles throughout the environment.
- Carbon in the biosphere is found in all organisms.
- Carbon in the hydrosphere is found as dissolved carbon dioxide.
- Carbon in the lithosphere is found in carbonate minerals and fossil fuels.
- Carbon enters the atmosphere from natural processes including respiration, decomposition, combustion, and volcanism.
- Carbon dioxide from the atmosphere becomes part of living organisms (the biosphere) through photosynthesis.
- Human activities remove carbon from the lithosphere (e.g. combustion of fossil fuels, cement production) and biosphere (e.g. logging) and release it into the atmosphere.
- Carbon, as carbon dioxide or methane, is a greenhouse gas.
- Greenhouse gases increase the amount of thermal energy trapped by the atmosphere and include water, carbon dioxide, and methane.
- An increase in greenhouse gases causes global heating, leading to climate change.
- Joseph Priestly (1733–1804) discovered oxygen and explored its role in plant-based air renewal and the carbon cycle.
- Thomas Chamberlin (1843–1928) developed a model of the carbon cycle, linking geological and atmospheric processes.
- Note: See Social Science learning area — Geography strand.
| Spheres of the Earth - Using models to explain how Earth’s spheres interact through matter cycles and energy transfer
- Comparing how energy is transferred and matter cycles in polar and tropical regions (e.g. differences in the atmosphere, biosphere, and hydrosphere)
| Carbon cycle - Interpreting data sets, diagrams, and maps to illustrate how carbon is transferred and transformed across the atmosphere, biosphere, hydrosphere, and lithosphere and to evaluate the impact of human actions on these natural flows
- Researching how changes in natural processes and human activities affect the movement and storage of carbon across Earth’s spheres
- Interpreting data and models to make predictions about how greenhouse gases influence Earth’s energy balance and climate
- Applying understanding of carbon movement to real-world contexts (e.g. climate change mitigation, land use planning, energy choices), using evidence to evaluate the effectiveness of different strategies
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| | Expanding Space - Gravity is the fundamental force that governs the behaviour and interactions of all matter in the universe. It influences the motion of objects on Earth, the orbits of celestial bodies within the Solar System, and the structure and dynamics of galaxies such as the Milky Way.
- The observable universe is limited by the speed of light and the age of the universe.
- A light year is the distance light travels in a vacuum in one Earth year.
- An astronomical unit (AU) is the average distance between the Earth and the Sun.
- The Big Bang theory describes the origin of the universe, which originated at a single point and is continually expanding.
- Evidence for the Big Bang theory includes the observation that galaxies are moving away from each other — showing that the universe is expanding — and the cosmic microwave background, which is faint electromagnetic radiation from the early universe.
- Ole Rømer (1644–1710) demonstrated that light travels at a finite speed using astronomical observations of Jupiter’s moon Io
- Edwin Hubble (1889–1953) discovered the expansion of the universe and established the relationship between galaxy distance and redshift, supporting the Big Bang theory.
- Beatrice Tinsley (1941–1981) made pioneering contributions to galaxy evolution and cosmology, influencing models of the expanding universe.
| | Expanding Space - Using scientific data (e.g. light years, astronomical units) to interpret and compare the size of, and distances between, celestial bodies, as well as the time scales of events in space
- Using evidence such as models, simulations, and visual representations to explore astronomical phenomena (e.g. fusion in stars, planetary motion, origin of the universe) and to illustrate the observational limits of current technologies
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