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Questions and Answers
What is ionisation?
When electrons have been removed from an atom or molecule, it's been ionised.
Define the term 'first ionisation energy'.
The first ionisation energy is the energy needed to remove 1 electron from each atom in 1 mole of gaseous atoms to form 1 mole of gaseous 1+ ions.
What's the equation for the 1st ionisation energy of oxygen?
O(g) ---> O+(g) + e- (1st ionisation energy = +1314 kJ mol-1)
What are the three important rules about ionisation energies?
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How does a higher ionisation energy affect the energy needed to remove the electron from an atom or molecule?
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What three factors affect ionisation energy?
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How does nuclear charge affect ionisation energy?
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How does distance from nucleus affect ionisation energy?
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How does shielding affect ionisation energy?
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Why is ionisation always an endothermic process?
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Of lithium and sodium, which has the higher ionisation energy, and why?
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Define the term 'second ionisation energy'.
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What's the equation for the 2nd ionisation energy of oxygen?
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Why are second ionisation energies greater than first ionisation energies?
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Why is the second ionisation energy of lithium much higher than the first?
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What is meant by successive ionisation energies?
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Study Notes
Ionisation Definition
- Ionisation involves the removal of electrons from an atom or molecule.
First Ionisation Energy
- Energy required to remove 1 electron from each atom in 1 mole of gaseous atoms to form 1 mole of gaseous 1+ ions.
First Ionisation Energy of Oxygen
- Equation: O(g) → O+(g) + e-
- First ionisation energy = +1314 kJ mol⁻¹.
Important Rules about Ionisation Energies
- Utilise the gas state symbol (g) as measurements are for gaseous atoms.
- Reference 1 mole of atoms rather than individual atoms.
- Lower ionisation energy facilitates easier formation of positive ions.
Impact of High Ionisation Energy
- High ionisation energy indicates strong attraction between the electron and the nucleus, requiring more energy for electron removal.
Factors Affecting Ionisation Energy
- Nuclear charge: More protons result in higher ionisation energy due to increased attraction.
- Distance from nucleus: Electrons closer to the nucleus experience stronger attraction, resulting in higher ionisation energy.
- Shielding: Increased number of inner electrons reduces outer electron attraction to the nucleus, impacting ionisation energy.
Nuclear Charge and Ionisation Energy
- Higher nuclear charge correlates with higher ionisation energy due to increased positive charge attracting electrons.
Distance from Nucleus and Ionisation Energy
- Attraction decreases rapidly with distance; closer electrons have higher ionisation energy due to stronger attraction.
Shielding and Ionisation Energy
- Greater shielding from inner electrons leads to less attraction felt by outer electrons, thus increasing ionisation energy.
Endothermic Nature of Ionisation
- Ionisation is an endothermic process because energy input is required to remove an electron from an atom or molecule.
Comparison of Ionisation Energies of Lithium and Sodium
- Lithium has a higher ionisation energy (+519 kJ mol⁻¹) than sodium (+496 kJ mol⁻¹) due to greater distance and shielding experienced by sodium's outer electron.
Second Ionisation Energy
- Energy needed to remove an electron from each ion in 1 mole of gaseous 1+ ions.
Second Ionisation Energy of Oxygen
- Equation: O+(g) → O2+ + e-
- Second ionisation energy = +3388 kJ mol⁻¹.
Comparison of First and Second Ionisation Energies
- Second ionisation energies exceed first ionisation energies because the removal is from a positive ion, requiring more energy.
Second Ionisation Energy of Lithium
- Higher due to removal from the first shell (1s²), which is closer to the nucleus and experiences no shielding.
Successive Ionisation Energies
- The process includes removing all electrons from an atom, resulting in successive ionisation energies, each corresponding to the removal of an electron.
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Description
Explore the fundamental concepts of ionisation and ionisation energies with this quiz. Test your knowledge on definitions, equations, and specific details regarding atomic structure related to ionisation. Perfect for students studying chemistry.