Combined Science

• Enzymes


  Large protein molecules, which have an active site with a unique shape to bind a specific substrate molecule
• Limiting reactant


  The reactant that gets used up first in a reaction
• Physical properties of group 7 halogens

  • Low melting point
  • Exist as a pair
• As you go down group 1


  The metals become more reactive
• Reason for trend in reactivity in group 1

  The outermost electron is further from the nucleus so it's easier to lose
• Group 1 metals reactivity 


  • They react vigorously with water releasing hydrogen
• physical properties of Group I metals (alkali)

  • Soft with a low density
• Atomic number


  The number of protons
• Particles found in an atom

  • Protons
  • Neutrons
  • Electrons
• Homozygous


  Both alleles for one gene are the same
• Group I metals (alkali)

  • Shiny
  • Good conductors
  • Usually dense
• Shell


  The innermost shell (the first shell) has the lowest energy level
• Reason for gaps in periodic table

  • For elements that had not yet been discovered
  • But he made predictions about the missing elements
• What happens when energy levels are full

  1. When the shell of an atom is full, the atom is completely stable

  2. Then they only become reactable to become stable
• Properties of non-metals


  • Dull
  • Brittle
  • Insulators
• What happens when halogens react with metals

  They form ionic compounds called salts
• Why does the boiling point increase as you go down a group

  Because the atom gets bigger
• What do the periods represent

  They represent energy levels, also known as shells
• Mass number


  The number of protons and neutrons
• Signs a reaction is taking place


  • Releasing gas
  • Change of smell
  • Popping
  • Fizzing
  • Precipitation
  • Combustion
  • Colour change
• Gas being given off indicates a reaction is taking place
• Conservation of mass


  No atom can be created or destroyed during chemical reactions, so the mass of the reactants must equal the mass of the products
• Diatomic molecule


  A molecule with 2 atoms (halogens)
• Equation for Concentration


  1. Concentration = volume ÷ mass
• Concentration


  • A measure of the amount of a substance in a volume of liquid
  • A measure of how much solute is dissolved per unit
• Unit for Magnetic flux density

  Tesla (†)
• Energy Stores


  • Kinetic
  • Thermal
  • Electromagnetic
  • Nuclear
  • Gravitational
  • Elastic
  • Potential
  • Chemical
• 1 dm³


  1000 cm³
• 1 m³


  1000 dm³
• Spring Constant Equation


  K = F/e
• Spring Constant


  Force extension (N/m)
• Hooke's Law


  The extension of a spring is directly proportional to the force applied, provided that the limit of proportionality is not exceeded
• Equation for work done


  Work done = force x distance
• Work done


  The measure of energy transfer when a force (F) moves an object through a distance (s)
• Percentage Composition


  The percentage of an element in a compound
• Relative Formula Mass


  The sum of the relative atomic masses in a substance
• Where does deoxygenated blood then flow through?

  1. the right atrium

  2. and then pumped out of the heart
• Fungi


  Spore-producing organisms which include moulds, yeast and mushrooms
• Metal


  An element which gas loses electrons to form a positive charge
• Non-metal


  An element which gains electrons to form a negative charge