Inorganic chemistry
- Created by: Kayliss71
- Created on: 21-05-18 10:04
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- Inorganic chemistry
- Periodicity
- The periodic table arranges elements by proton number
- Melting point is linked to bond strength and structure
- Ionisation energy generally increases across a period
- This is because of the increasing attraction between the outer shell electrons and the nucleus
- Atomic radius decreases across a period
- This is due to extra protons increasing the positive charge of the nucleus so electrons are pulled closer to the nucleus making the atomic radius smaller
- Group 2
- Atomic radius increases down the group
- Due to the extra electron shells that are added
- First ionisation energy decreases down the group
- Each element down group 2 has an extra electron shell
- Due to the extra shells shielding occurs and shells are further away from positive nucleus so attraction is weaker
- Melting point generally decrease down the group
- Have typical metallic structures, going down the group metal ions get bigger but number of delocalised electrons stay the same
- Larger the ionic radius = further away delocalised electrons are from positive nuclei so less attraction so less energy needed to break bonds
- Reactions with water
- Be doesn't react
- Mg reacts very slowly
- Ca reacts steadily
- Sr reacts fairly quickly
- Ba reacts rapidly
- Reactivity increases down the group, weaker the ionisation energy = more reactive
- Uses of group 2 metals
- Calcium hydroxide is used in agriculture to neutralise soils
- Magnesium hydroxide is used in some indigestion tablets to neutralise excess stomach acid
- Barium sulfate is used in barium meals which help soft tissue to show up on x-rays
- Magnesium is used in the extraction of titanium
- Calcium oxide and calcium carbonate is used to remove sulfur dioxide
- Use flame tests to identify Group 2 ions
- Calcium- brick red
- Strontium - red
- Barium- pale green
- Atomic radius increases down the group
- Group 7
- Boiling points increase down the group due to increasing van der waals as size and relative mass increases
- Electronegativity decreases down the group due to electron shielding
- Halogens displace less reactive halide ions from solution
- Halogens become less oxidising down the group
- Uses of group 7
- Chlorine and sodium hydroxide make bleach
- 2NaOH + Cl2 --> NaClO + NaCl + H2O
- Chlorine is used to kill bacteria in water
- Chlorine and sodium hydroxide make bleach
- Halides
- Their reducing powers decrease down the group
- Reactions with sulfuric acid
- NaF + H2SO4 -> NaHSO4 + HF *same for NaCl
- 1) NaBr + H2SO4 --> NaHSO4 + HBr
- 2) 2HBr + H2SO4 --> Br2 + SO2 + 2H2O
- 1) NaI + H2SO4 --> NaHSO4 + HI
- 2) 2HI + H2SO4 --> I2 + SO2 +2H20
- 3) 6HI + SO2 --> H2S + 3I2 + 2H2O
- 2) 2HI + H2SO4 --> I2 + SO2 +2H20
- Silver nitrate is used to test for halides
- Fluoride - no precipitate
- Chloride - white precipitate
- Bromide - cream precipitate
- Iodide - yellow precipitate
- You can test your results by adding ammonia solution
- Chloride - white precipitate, dissolves in dilute ammonia solution
- Bromide- cream precipitate, dissolves in conc ammonia solution
- Iodide- yellow precipitate, insoluble in conc ammonia solution
- Period 3 elements and metal oxides
- Reactions with water
- Sodium reacts vigorously with cold water ( pH 12-14)
- 2Na + 2H2O --> 2NaOH + H2
- Magnesium reacts very slowly with cold water and forms a weakly alkaline solution (pH 9-10)
- Magnesium is sparingly soluble, so reacts faster with steam
- Sodium reacts vigorously with cold water ( pH 12-14)
- Reactions with oxygen
- Sodium oxide: 2Na + 1/2O2 --> Na2O
- Reacts vigorously
- Aluminium oxide; 2Al + 1 1/2O2 --> Al2O3
- Slow (reacts faster if powdered)
- Phosphorus (v) oxide; P4 + 5O2 --> P4O10
- Spontaneous combustion
- Magnesium oxide; Mg + 1/2O2 --> MgO
- reacts vigorously
- Silicon dioxide: Si + O2 --> SiO2
- Slow
- Sulfur dioxide; S + O2 --> SO2
- Burns steadily
- Sodium oxide: 2Na + 1/2O2 --> Na2O
- Simple non metal covalent oxides
- Form strong acids
- Phosphoric (V) acid : 1) P4O10 + 6H2O --> 4H3PO4
- 2) H3PO4 --> 3H(+) + PO4(3-)
- Sulfurous acid: 1) SO2 + H2O --> H2SO3
- 2) H2SO3 --> 2H(+) + SO3(2-)
- Sulfuric (VI) acid : 1) SO3 + H2O --> H2SO4
- 2) H2SO4 --> 2H(+) + SO4(2-)
- Neutralising Equations
- Basic oxides neutralise acids
- Na2O + 2HCL --> 2NaCl + H2O
- MgO + H2SO4 --> MgSO4 + H2O
- Acidic oxides neutralise bases
- SiO2 + 2NaOH --> Na2SiO3 + H2O
- P4O10 + 12NaOH --> 4Na3PO4 + 6H2O
- SO2 + 2NaOH --> Na2SO3 + H2O
- SO3 + 2NaOH --> Na2SO4 + H2O
- Amphoteric oxides neutralise acids and bases
- Acid: Al2O3 + 3H2SO4 --> Al2(SO4)3 + 3H2O
- Base: Al2O3 + 2NaOH + 3H2O --> 2NaAl(OH)4
- Basic oxides neutralise acids
- Reactions with water
- Tests for Ions
- Use red litmus paper to test for ammonium ions - paper will turn from red to blue
- Red litmus paper will also turn blue if hydroxides are present
- Use HCL and barium chloride to test for sulfates - a white precipitate will form
- Red litmus paper will also turn blue if hydroxides are present
- Use HCL to test for carbonates, will fizz if present and gas given off will turn lime water cloudy when bubbled through (if gas is CO2)
- Use red litmus paper to test for ammonium ions - paper will turn from red to blue
- Periodicity
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