Chemistry inorganic
- Created by: rach555
- Created on: 21-05-18 12:23
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- Inorganic
- Group 2
- Atomic radius
- Atomic radii increase going down
- Each element has an extra filled main level of electrons
- Melting points
- Going down, electrons in 'sea' are further away from positive nuclei
- Strength of metallic bond decreases
- Melting point decreases down group
- Ionisation energy
- Lose 2 electrons
- Both ionisation energies decrease down group
- More electron shells means more shielding so easier to remove electrons
- Less attraction, easy to remove
- Reaction with water
- Metals get more reactive going down
- Redox reactions
- In cold water magnesium reacts slowly
- In steam magnesium reacts rapidly to form an alkaline oxide and hydrogen
- Basic reaction forms an alkaline hydroxide and hydrogen
- Extraction of titanium
- Most metals extracted by reacting metal oxide with carbon to form metal and CO2
- But doesn't work for titanium
- So titanium oxide reacts with chlorine and carbon to form titanium chloride, TiCl4 and CO2
- Then TiCl4 is reduced to titanium by reacting with magnesium
- Solubility
- Hydroxides
- Going down group, they become more soluble
- E.G Mg(OH)2 is almost insoluble but Ba(OH)2 dissolves
- Sulfates
- Going own group, they become less soluble
- Barium sulfate (BaSO4) is basically insoluble so can be taken as a barium meal to outline gut in medical X-rays
- Sulfate ion test
- Sulfate ion solution is acidified with nitric or hydrochloric acid (removes carbonate ions).
- Then barium chloride is added and white precipitate of barium sulate forms
- Barium carbonate is also a white insoluble sold so confused with barium sulfate
- Hydroxides
- Flue gases
- React an alkali, CaO or CaO3 slurry with flue gases
- Called wet scrubbing. Removes SO2
- Group 2 neutralise acids- Ca(OH)2 neutralises acidic soils. Mg(OH)2 neutralises stomach acid
- Atomic radius
- Group 7
- Electronegati-vity
- Bond gets further away as atoms get larger down group
- Increases electron shielding
- Electronegati-vity decreases down group
- Physical properties
- Fluorine is a pale yellow gas, chlorine is a green gas
- Bromine is a red-brown liquid, iodine is a black solid
- Atomic radius increases down group as another shell as going down
- Melting and boiling points
- Increases down group
- Larger atoms have more electrons so van der Waals forces stronger
- Oxidising ability
- Halogens are oxidising agents so are reduced (gain an electron)
- Decreases going down group
- Displacement reactions
- Halogens react with metal halides
- in a way that the halide will be displaced by a more reactive halogen not a less reactive one
- E.G chlorine will displace bromide ions
- Use ionic equations. any non group 7 element is a spectator ion
- Reducing ability
- Larger ions lose electrons easier, so reducing power increases down group
- Halide ions act as reducing agents
- Solid sodium halides react with concentrated sulphuric acid
- Sodium chloride
- Steamy fumes of hydrogen chloride released. Solid product is sodium hydrogensulfate
- Not a redox reaction, as chloride ion is too weak a reducing agent
- Acid based reaction
- Sodium bromide
- Steamy fumes of hydrogen bromide and brown fumes of bromine. Colourless sulphur dioxide formed
- First reaction is acid based and produces NaSO4 and HBr
- In second reaction, bromide ions are strong reducing agents to reduce sulphuric acid to sulphur dioxide.
- In second reaction, the bromine is formed and water
- Sodium iodide
- Steamy fumes of hydrogen iodide, black solid of iodine, and hydrogen sulphide gas.
- Yellow solid sulfur may be seen. And colourless sulfur dioxide
- First reaction is acid based
- Second reaction is redox. Iodide ions are best reducing agents
- Sodium chloride
- Uses of chlorine
- Swimming pools and drinking water
- Chlorine reacts with water to form HClO and HCl
- One chlorine atom increases oxidation state and the other decreases- called disproportion
- Chloric acid is an oxidising agent and kills bacteria
- Chlorine reacts with cold, dilute sodium hydroxide to form sodium chlorate, is a disproportion reaction. Used in bleach
- Swimming pools and drinking water
- Identify metal halides with silver ions
- All metal halides (not fluoride) react with silver ions in aqueous solution
- Solution is acidified by dilute nitric acid to remove other ions
- F- no precipitate, Cl- has white precipitate, Br- has pale very cream precipitate, I- has very pale yellow precipitate
- Ammonia solution added to precipitates
- Silver chloride dissolves in dilute ammonia
- Silver bromide dissolves in concentrated ammonia
- Silver iodide insoluble in ammonia
- Electronegati-vity
- Period 3
- Melting and boiling points
- 1.Sodium to aluminium
- Strength of metallic bond increases
- Charge on ion increases so more electrons join delocalised sea
- Increase melting and boiling points
- 2.Silicon
- Giant covalent (macromolec-ular)
- Increase melting and boiling point
- 3.Phosphorus to chlorine
- Molecular so depends on size of Van der Waals forces
- More electron means greater attration
- Melting/boiling point= S8>P4>CL2
- 1.Sodium to aluminium
- Atomic radii
- Adding protons to nucleus and electrons to shell
- Increased charge pulls electron closer to nucleus
- Stronger nuclear attraction
- Size of atom decreases
- Ionisation energy
- Increases across period
- Number of protons increase and electrons enter same level
- Increased charge makes it difficult to remove electrons
- 1.Magnesium to aluminium
- Mg loses a 3s electron
- Al loses a 3p electron
- P-electron is a higher energy level. So less energy to remove
- 2.Phosphorus to sulfur
- P has no paired electron in a p orbital
- S has two p electrons paired in a p-orbital so easier to remove due to repulsion
- Melting and boiling points
- Group 2
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