Science s2 Exam revision 2025 (copy)

Earths 4 Spheres

  • Lithosphere

  • Hydrosphere

  • Biosphere

  • Atmosphere

Interactions between spheres

  • Hydrosphere relates to atmosphere and biota

  • Atmosphere relates to hydrosphere, biota and lithosphere

  • Lithosphere relates to biota and atmosphere

Greenhouse effect

  • When the greenhouse gases trap some of the energy leaving the Earths surface. This is to keep the warm temperature.

  • Main gases are carbon dioxide, methane, nitrous oxide, water and ozone

  • Without the greenhouse effect the average temperature on earth would be about -18 degrees Celsius so life would not exist

Quadrat sampling

  • 1. Mark out the quadrat, 2. record data, 3. repeat the process, 4. analyse the results

Transect line sampling

  • 1. set up the transect, 2. choose sampling points, 3. place quadrats or make observations, 4. record data, 5. analyse your findings

Bohr diagram

  • Diagram with the chemical symbol in the middle and electrons in the shells surrounding

  • Shell order is as follows 2, 8, 8, 18

Ionic formula

  • Chemical formula for ionic compound

Balancing equations

  • Identify reactants and products in chemical reactions

  • Number of each element is the same on both sides

  • Structure = Reactant + Reactant —> Product

State symbols

  • Solid (s)

  • Liquid (l) (water only)

  • Gas (g)

  • Aqueous (aq) (substance dissolved in water)

Chemical change

  • Solid appears or disappears

  • Gas is produced / smell is given off / bubbles appear

  • Temperature increases or decreases

  • Flame or light appears

  • Change in colour is seen

Types of reactions

  • Combustion reactions

  • Neutralisation reactions

  • Precipitation reactions

Combustion reactions

  • Rapid chemical reaction with oxygen releasing heat and light energy

  • Exothermic process meaning they release energy

  • Combustion powers heating, transportation, and electricity generation, playing a vital role in daily energy use

Neutralisation reactions

  • Occur when an acid reacts with a base to produce a salt and water

  • General form of a neutralisation reaction is: Acid + Base —> Salt + Water

  • Neutralisation reactions are widely used in everyday life and industry.

  • E.g antacids neutralise excess stomach acid to relieve heartburn and in agriculture lime (calcium hydroxide) is used to neutralise acidic soils

Precipitation reactions

  • Occur when 2 aqueous solutions react to form an insoluble solid, known as a precipitate

  • General form o a precipitation reaction is AB(aq) + CD(aq) —> AD(s) + CB(aq), where AD is the precipitate

  • Precipitation reactions are important in analytical chemistry for qualitive analysis and in various industrial processes, such as the removal of unwanted ions from water in water treatment plans

Reactivity

  • Orders metals and non-metals that can be isolated from ores and minerals

  • Reactivity series is ordered based on readily the element loses or gain and electron

Experimental variables

  • Specific characteristics or factors that are manipulated and measured in order to test a hypothesis

Hypothesis

  • Proposed explanation for a phenomenon

Results

  • What was the data from the prac?

  • What was the process or product obtained from the prac?

Discussion

  • One of the final parts of a research paper, in which an author describes, analyzes, and interprets their findings

Conclusion

  • Sums up what has been found out during a investigation

Waves

  • Wavelength - Distance between two waves (same point) found by

  • Frequency

  • Wave speed

  • Period

  • Peak

  • Crest

  • Trough

  • Mean position

  • Longitudinal

  • Transverse

  • Rarefaction

  • Compression

  • Dispersion

  • Difference between frequency and wavelength on a wave diagram

  • Period of wave if the frequency is given

  • Relationship between wavelength, frequency and wave speed

  • Motion of particles in a transverse or longitudinal wave

  • How to draw a transverse and longitudinal wave

Light

  • Speed of light in a vacuum

  • Electromagnetic spectrum

  • Order of non-visible frequencies from radio waves through to gamma rays based on both frequency and wavelength

  • Order of colours in the visible part of the electromagnetic spectrum

  • How prisms can be used to split up different frequencies of light

  • How to predict the location of an image after reflection takes place

  • What causes light to bend as it enters different mediums

  • Predict the path of light as it passes through different mediums (refraction)

  • Light doesn’t need a medium to travel through

Sound

  • How sound affects particles in a medium

  • How the ear detects sound and can label the inside of an ear

  • Pitch and loudness description in terms of the properties of the wave

  • Units for measuring sound

  • Sonar and echolocation explaination of how it works

  • Relationship between speed, distance and time to perform calculations for sonar and echolocation

  • Infrared

  • Ultrasound

Energy

  • Law of conservation of energy

  • Types of energy include kinetic, potential, electric, thermal and electromagnetic (light)

  • Difference between energy transfer