Science

• how to find protons


  Same number as atomic number
• what does an isotope look like

  M.N/A.N element
• types of radioactivity


  alpha, beta and gamma
• Alpha radioactivity

  • high power of ionisation
  • low penetration
  • nucleus loses 2 protons and 2 neutrons
• Beta radioactivity

  • One electron
  • Charge of -1
  • Moderately ionising
  • no mass
  • low power/ionisation
  • high penetration
  • Nucleus loses either a proton OR gains a proton
• Gamma radioactivity

  • Waves of electromagnetic radiation after alpha and beta radiation
  • No mass and charge —> Weakly ionising
  • no charge in proton number, atom does not become a different element
  • highly penetrating
• How to find neutrons

  Mass number - protons
• isotopes

  • same elements
  • different mass number
  • same protons
• half life is when the amount of time for the no. of decays/activity to halve; fewer radioactive = lower activity

  • you’ll never know when it’ll decay
• key points in isotopes

  • different because of neutron properties
  • different mass numbers and neutrons
• Different types of ions

  cation and anions
• cation

  • loses electrons and has more protons
  • gives the atom a positive charge
  • t (+)
• anion

  • gains electrons
  • has electrons>protons
  • negatively charged
  • no t so no + (negative charged)
• different types of chemical reaction

  • combination
  • decomposition
  • displacement
  • double displacement
  • redox
• combination

  • 2 or more substances combined to form 1 substance
  • 2 or more reactants to create one product
• decomposition

  • opposite of combination reaction
  • 1 compound breaks into 2 or more simpler substances
  • AB=A+B
  • you have 2 or more products but only 1 reactant
• displacement

  • more active element displace less active element AKA single displacement reactions
  • A+BC=AC+B because A is more reactive than B, so it ‘kicks’ off B from C
• Double displacement

  • 2 compounds react with each other and exchange their irons to form 2 new compounds
  • AB+CD=CB+AD
  • exchange either cations or anions NOT BOTH
• redox

  • REduction + OXidation
  • reduction = addition of hydrogen
  • oxidation = addition of oxygen
  • reactants get oxidised or reduced, not the products
• Endothermic reaction

  • When heat (thermal energy) is absorbed -> ENter (into substance)
  • Temperature of substance decrease
• Exothermic reaction

  • When heat (thermal energy) is released -> think EXit (leaving the substance)
  • Temperature of surroundings increase
• radioisotope

  • unstable form of a chemical element that releases radiation as it breaks down -> becomes more stable
• How to tell what’s acidic, basic or neutral

  • acid solution has H+>OH-
  • basic solution has OH->H+
  • neutral solution has H+=OH-
• acidic solution

  • donates hydrogen ions (H+)
  • acid is dissolved in water, balance between H+ and OH- is shifted
  • more H+ than OH- in solution
• bases/alkaline solution

  • accepts hydrogen ions
  • base dissolves in water, balance between H+ and OH- shifts opposite ways
  • resulting to OH->H+
• properties of acid

  • corrosive
  • sour taste
  • turns blue litmus paper red
  • react with some metal, releasing hydrogen gas and salt residue
  • neutralised by gas (producing salt and water)
• properties of bases/alkaline

  • caustic
  • soapy, slimy feeling
  • bitter taste
  • turns blue litmus paper red
  • neutralised by bases (producing salt and water)
  • conduct electricity (think alkaline battery)
  • alkali base dissolves in water
• pH scale

  • measures how acidic/basic a solution is
  • measure H+ concentration
  • ranges 0-14
• acidic solution

  • ph 0-7
  • solution 0 is very acidic (a lot of H+)
• neutral solution

  • ph7
  • hydrogen ion (H+) = hydroxide ion (OH-)
• basic solution

  • ph above 7
  • ph 14 is very basic (very little H+)