B1 Revision Notes Ocr 21st Century Science Coursework

This section for students studying the current (2011 onwards) Science course. If you are studying the old (pre-2011) course, please visit the pre-2011 course index.


You and your genes
Genes, inheritance, testing and treating genetic diseases, cloning and stem cells
Keeping healthy
Disease and resistance, antibiotics and drug testing, heart disease, keeping a healthy balance
Life on Earth
How species depend on each other, theory of evolution, the importance of biodiversity


Air quality
Chemicals in the air, chemical reactions and pollutants, improving air quality
Materials choices
Measuring properties of materials, crude oil and its uses, structure of materials, nanotechnology
Chemicals in our lives - risks and benefits
Minerals in Britain, the importance of salt, manufacture and use of chemicals, safety and sustainability


The Earth in the Universe
Earth, stars, galaxies and space, how the Earth is changing
Radiation and life
Electromagnetic radiation, benefits and risk, global warming, waves and communication
Sustainable energy
Using energy, generating electricity, choosing energy sources

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C4 - Chemical Patterns

  • Line spectra
    • When heated, the electrons in atoms vibrate, releasing energy as light
    • The wavelengths emitted can be recorded as line spectra - different due to different electron arrangement
    • Some elements emit distinctive colours when heated
  • History of the periodic table
    • Dobereiner (1828) - sorted into triads, middle element = the mean of the other two (atomic mass)
    • Newlands (1865) - rows of seven in order of atomic mass, coloumns similar; groups in Newlands' method combined dissimilar elemnts, mixed metals + non-metals, no spaces for undiscovered elements
    • Mendeleev (1869) - order of atomic mass, left gaps to keep groups similar, method confirmed when new elements were found and fitted the trend
  • Electron shells
    • 1st shell, 2 electrons; every shell after, 8 electrons
  • Ionic bonding
    • Made between two ions (charged atoms) - one positive, one negative
    • Happens when electrons needed to fulfill complete outer shell equals the amount needed to be dropped - eg. G1 and G7 elements ionically bond
    • Ionic compounds form a regular lattice (crystal); only conduct electricity when molten
  • Group 1 - Alkali metals
    • All very reactive due to one electron in outermost shell
    • All shiny when freshly cut; tarnish in air as they react with oxygen
    • Going down, becomes more reactive, higher density, lower boiling point 
    • Reacts with cold water to give fizzing from hydrogen, makes solution alkali, creates hydroxide of the metal - eg. 2Na(s) + 2H2O(l) --> 2NaOH(aq) + H2(g)
    • Reacts with chlorine to give vigorous reaction producing colourless crystalline salts
  • Group 7 - Halogens
    • Seven outer electrons, making them very reactive
    • Going down, becomes less reactive, higher boiling points
    • Flourine - yellow vapour; chlorine - green; bromine - orange; iodine - dark grey solid, purple vapour
    • Reacts with alkali metals to make salts called metal halides
    • Reacts with iron to form colourless solids called iron halides

C5 - Chemicals of the Natural Enviornment

  • Chemicals in the atmosphere
    • 78% nitrogen, 21% oxygen, 1% other (inc. 0.04% carbon dioxide)
    • Molecular substances are small, meaning weak forces of attraction, making boiling points low
    • Pure molecular substances don't conduct electricty as there are no free electrons
  • Covalent bonding
    • Atoms share an electron to acheieve a full outer shell - held to together by electrostatic attraction between the positive nuclei and negative electrons
  • Chemicals in the hydrosphere
    • Consists of all water in oceans, seas, lakes…

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