F321: Atoms and Reactions

Atomic Structure & Masses
1. Isotopes of the same element have: different masses, the same number of electrons and protons, different number of neutrons
2. Calculate relative atomic mass, decimal percentage multiplied by the isotope mass number
3. Relative masses: Proton = 1, Neutron = 1, electron = 1/2000
4. Relative charge = -1 electron, 1 proton, 0 neutron
Definitions:
1. Isotopes:- atoms of an element with different numbers of neutrons and different masses
2. Relative isotopic mass - the mass of an atom of an isotope of an element compared with one 1/12 of the mass of c12
3. Relative atomic mass - the weighted mean mass of an atom of an element compared to 1/12 of the mass of c12
4. Molar Mass - mass per mole of a substabce
5. Empirical formula - simplest whole number ration of atoms of each element present in a compound
6. Molecular formula - the actual number of atoms of each element present in a compound
7. Atomic Number - the number of protons in the nucleus of an atom
8. Mass Number - the number of atoms in the nucleus
9. Ion - a positively of negatively charged atom
10. Relative molecular mass - the weighted mean mass of a molecule compared with 1/12 of the mass of c12
11. Relative formula mass - the weighted mean mass of a formula unit compared to 1/12 the mass of c12
12. Amount of substance - the quantity whose unit is the mole
13. Mole - the amount of any substance containing as many particles as there are carbon atoms in exactly 12g of the c12 isotope
14. Molecule small group of atoms covalently bonded
15. Molar volume - the vol per mole of a gas, units = dm3 mol-1, at room temp and pressure aprox 24
16. Concentration - of a solution is the amount of mil dissolved in 1 dm
17. Stoichiometry - the molar relationship between relative quantities of substances taking part in a reaction
18. Acid - proton donor
19. Base - proton acceptor
20. Alkali - a type of base that dissolves in water to form OH- ions
21. Salt - a chemical compound formed when an h+ from an acid id replaced with a metal ion
22. Oxidation Number - is a measure of the number of electrons that an atom used to bond with atoms of another species
23. Oxidation - loss of electrons or an increase in oxidation number
24. Reduction - gain of electrons or a decrease in oxidation number
25. Redox reaction - a reaction where oxidation and reduction takes place
26. Reducing Agent & Oxidising agent - reducing - a reagent that reduces(adds electrons to) another species. Oxidation - a reagent that oxidises ( takes electrons from) another species
Formulas
1. moles=mass/mr
2. Gas volumes
  1. vol in (dm) moles=V/24
  2. Vol in (cm) moles=v/24000
3. Moles = conc x vol(dm)
4. Moles = conc x vol/1000 (cm)
Acids and Bases
1. Acids
  1. Sulphuric Acid --> H2SO4
  2. Hydrochloric Acid --> HCl
  3. Nitric Acid --> HNO3
  4. When an acid is added to water it releases H+ ions into the solution
2. Bases
  1. Common bases are metal oxides and hydroxides
  2. Bases neutralise acids
3. Alkalis
  1. Sodium hydroxide --> NaOH
  2. Potassium Hydroxide --> KOH
  3. Ammonia --> NH3
  4. An alkaline is a special base that dissolves in water forming aqueous OH- ions
Salts
1. A salt is an ionic compound with the following: positive ion (cation) is usually a metal ion or an ammonium ion. The negative ion (anoin) in a salt is derived from an acid.
2. Salts can be made from: carbonates, bases, alkalis
3. Salts from carbonates: Acid + Carbonate --> Salt + Water + CO2
4. Salt from Bases: Acid + Base --> Salt + Water
5. Salt from Alkalis: Acid + Alkali --> Base + Water
6. Ammonium Salt & Fertilisers
  1. Ammonium salts are formed when acids are neutralised by aqueous ammonia
  2. NH3 + HNO3 --> NH4NO3
Titartions
1. Colour changes
  1. Bromothymol Blue
    1. Colour in Acid - Yellow
    2. End Point - Green
    3. Colour in Base - Blue
  2. Methyl Orange
    1. Colour in acid - Red
    2. Colour in Base - Yellow
    3. End Point - Orange
  3. Phenolphthalein
    1. Colour in acid - Colourless
    2. End Point - Pale Pink
    3. Colour in Base - Pink
Oxidation & Reduction
1. Oxidation
  1. Oxidation Numbers
    1. Uncombined element = O
    2. Combined Oxygen = -2
    3. Combined Hydrogen = +1
    4. Simple Ion = charge on ion
    5. Combined Fluorine = -1
    6. Chlorine usually = -1
  2. Oxidation numbers in chemical names
    1. Compound of transition element usually indicate the oxidation number in the name
  3. The sum of the overall oxidation numbers must equal the overall charge
2. Reduction
  1. non metals tend to be reduced whilst metals tend to be oxidised
  2. A reaction in which oxidation and reduction occurs is called a redox reaction
  3. TIP - write each oxidation number below each atom and then calculate whether its oxidation or reduction
  4. Redox reaction of Acids and metals:- the metal is oxidised, forming positive metal ions, the hydrogen in the acid id reduced, forming the element hydrogen as a gas
3. Oxidation is gain of oxygen - Reduction is the loss of oxygen
4. Oxidation is the loss of electrons - Reduction is the gain of electrons
5. Reduction is a decrease in oxidation number - Oxidation is an increase in oxidation number

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