EL Flashcards
Atomic structures
Dalton - spheres
Thompson - electrons (ppm)
Rutherford - nucleus (gold leaf)
Bohr - shells (EM radiation)
What are features of a giant ionic structure?
- most dissolve in water –> water is polar
- conduct when molten/aq
- high melting point (strong electrostatic forces of attraction)
Are simple or dative covalent bonds stronger?
Simple
Examples of giant covalent structures
Graphite
Diamond
Structure of graphite
- 3 x C bonds
- Delocalised e-
- Layers slide due to weak IM forces
- Layers far apart = low density
- Insoluble due to strong covalent bonds
Structure of diamond
- 4 x C bonds
- Tightly packed
- Rigid
- Can be cut
- Very high mp/bp
- Very hard
- Doesn’t conduct
- Insoluble
Properties of metallic bonding
- Positive metal ions, delocalised sea of electrons
- Can conduct
- Electrostatic attraction
- High mp = insoluble
Good thermal conductors
Malleable/ductile
What is a tetrahedral molecule?
4 bonding pairs
109.5
What is a bent molecule?
2 bonding, 2 lone
104.5
What is a pyramidal molecule?
3 bonding, 1 lone
107
What is a linear molecule?
2 bonding
180
Group 2 + water
Metal hydroxide
Hydrogen
Group 2 + oxygen
Metal oxide
Solubility of group 2 carbonates
Decreases down group
Solubility of group 2 hydroxides
Increases down group
What is first ionisation enthalpy?
Minimum energy required to remove one mole of electrons from one mole of atoms in a gaseous state
Ionisation enthalpy trends: period/group
Along = increases (nuclear charge)
Down = decreases (shielding)
Period 2 ionisation energies
Increase except Boron and Oxygen
Boron - e- being removed from higher energy level (2p/2s)
Oxygen - repulsion in 2p
Period 3 ionisation energies
Increases
Aluminium and sulfur
Aluminium - (3s/3p) higher energy level further away from nucleus
Sulfur - repulsion in 3p
Melting points across period 2/3
Peaks in middle due to diff bonding
Metallic bonding (group 2>1)
Giant covalent (B/C/Si)
Simple covalent
Weak IM/full shell
What is a feature of emission/absorption spectra?
Lines get closer at higher frequencies
Why is the spectrum of an element unique?
Move up energy levels
Energy levels unique to each element
E = hv
