Chemistry 1.2
- Created by: selen.
- Created on: 19-04-15 11:19
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- Chemistry 1.2
- Ionisation energy
- energy required to remove one e¯ from each atom in 1mol(g) atoms to form 1mol of 1+ ions(g)
- Factors affecting ionisation energy:
- Nuclear charge
- greater nuclear attraction = greater attraction on valence e¯
- Atomic radius
- greater the atomic radius, smaller nuclear attraction
- E¯ shielding
- inner e¯ repel outer ones
- the more inner shells, the more shielding & less attraction between nucleus and valence e¯
- inner e¯ repel outer ones
- Nuclear charge
- Successive ionisation energies
- the measure of energy required to remove each e¯ in turn
- e.g. for Li there are 3 valence e¯
- Li = Li+ + e¯ Li+=Li2+ + e¯ Li2+=Li3++e¯
- e.g. for Li there are 3 valence e¯
- Each successive ionisation energy is larger than the one before
- as each e¯is removed there is less repulsion bwn e¯ so each shell is pulled in to nucleus
- so nuclear attraction increases so more energy needed
- as each e¯is removed there is less repulsion bwn e¯ so each shell is pulled in to nucleus
- the measure of energy required to remove each e¯ in turn
- Shells & Orbitals
- The shells can hold: 1st = 2e¯ 2nd = 8e¯ 3rd = 18e¯ 4th = 32e¯
- The orbitals
- S orbital can hold up to 2e¯
- P orbital can hold up to 6e¯
- D orbital can hold up to 10e¯
- F orbital can hold up to 14e¯
- Filling the shells
- Energy level 1: 1s
- Energy lvl2: 2s,2p
- Energy lvl 3: 3s, 3p, 4s, 3d
- Energy lvl 4: 4s, 4p, 4d, 4f
- Chemical Bonding
- Covalent
- 2 non-metals, where e- shared
- Simple Molecuar
- molecules held together by weak forces but the atoms within molecule held together by strong covalent forces
- Low MP&BP, do NOT conduct electricity and are soluble in NON-POLAR solvents (b/c vdw form)
- Giant covalent lattices
- High MP&BP b/c strong covalent bonds
- Non-conductors of electricity b/c no free charged particles (except in graphite)
- Insoluble in both POLAR& NON-POLAR b/c the bonds are too strong to be broken
- Metallic
- Occurs in metals bwn all atoms
- Giant metallic lattice
- High MP&BP b/c e¯ are free to move. The attraction bwn +ve ions & -ve e¯ is strong. So lot of energy needed to break the bonds
- Deloclalised e¯ which are able to move throughout the structure. Overall the charge is BALANCED
- Ionic
- Metal and non-metal, opposite charges attract
- The metal becomes a +ve ion and the non-metal a -ve ion
- Giant ionic lattices
- Each ion is surrounded by oppositely charged ions which attract to from a lattice
- High MP&BP so are solid at room temp. This is b/c lot of energy is needed to break strong electrostatic forces holding ions together
- the greater the charge, the greater the electrostatic attracion
- When solic annot conduct electricity b/c ions are fixed and cannnot move
- When solid they cannot conduct elctricty b/c ions are fixed so unable to move
- when melted or dissolved the lattice breaks down and the ions are free to move so can conduct elctricty
- Dissolves in POLAR solvent (water) as it breaks down the lattice by surrounding each ion to form a solution
- Metal and non-metal, opposite charges attract
- Covalent
- Inter molecular (IM) forces
- V. weak forces bwn small dipoles in diff. molecules
- Permanent dipole-dipole
- Polar molecules have permanent dipoles
- the permanent dipole in a diff. polar molecules from weak permanent dipole-dipole forces
- Polar molecules have permanent dipoles
- van der Waals'
- exist bwn ALL molecules
- weak IM attractions bwnv.small temporary dipoles in neighbouring moelcules
- caused by movement of e¯ in shells, unbalancing the charge distribution
- the more e¯ the greater the induced dipole, the greater the forces
- exist bwn ALL molecules
- Hydrogen bonding
- molecules containing OH and NH bonds are polar w/ permanent dipoles
- These bonds are STRONG dipole-dipole ineractions
- gives water special properties
- Ice is less dense thatwater b/c it is an OPEN LATTICE w/ H bonds holding the water mlecules apart
- when it melts these rigid H bonds collapse and the water moelcules move close togther
- Ice is less dense thatwater b/c it is an OPEN LATTICE w/ H bonds holding the water mlecules apart
- molecules containing OH and NH bonds are polar w/ permanent dipoles
- Ionisation energy
- e.g. for Li there are 3 valence e¯
- Li = Li+ + e¯ Li+=Li2+ + e¯ Li2+=Li3++e¯
- Ice is less dense thatwater b/c it is an OPEN LATTICE w/ H bonds holding the water mlecules apart
- when it melts these rigid H bonds collapse and the water moelcules move close togther
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