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Differentiate between Matter and Energy:
Matter: Particulate (chunk-like) and moves in definite paths.
Energy: Continuous (wave-like) and moves in all directions.
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Orbital Energy Depends On:
- 1. Greater nuclear charge, lower (stabalize) orbital energy.
- 2. Electron-electron repulsions, raise (destabalize) orbital energy.
- 3. Electrons in outer orbitals (higher n) are shielded from the full nuclear charge, so they have higher energy.
- 4. Orbitals with good penetration (having electron density close to nucleus), have lower energy.
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Effective Nuclear Charge (Z_Eff)
The nuclear charge an electron actually experiences as a result of shielding effects due to the presence of other electrons.
Shielding = lower Z_eff = charge makes electron easier to remove.
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Down a group:
- Zeff Constant
- Radius Increases
- EA Less Negative
- EN Decreases
- IE Decreases
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Across a Group (Left To Right)
- Zeff Increases
- Radius Decreases
- IE Increases
- EA More Negative
- EN Increases
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Reducing Agent
- Loses electron
- Is oxidized
- Oxidation # Increases
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Oxidizing Agent
- Gains electron
- reduced
- Oxidation # Decreases
*Halogens are easily reduced.
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How can you tell if a substance is a good oxidizing agent or a good reducing agent?
- RA:
- -easily loses electron (low IE)
- -Is in unusually low oxidation states
- OA:
- -easily gains electron (highly -ve EA)
- -is in unusually high oxidation states
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Hydrogen
- -Colourless gas, low mp, low bp
- -Most abundant element in universe (Stars)
- -Normally a nonmental
- -Preperation:
- 1.Most abundant source on earth is H20
- 2.Extraction of the element by reduction of H2O. Electrolysis is NOT a practical method.
- -Uses: 1. Production of Ammonia
- 2. In petroleum refining, converting oils to fats.
- Disadvantages: no cheap source and transport and storage are challenging.
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