Questions and Answers
What is the trend of ionization enthalpy across a period?
What is Ionization Enthalpy a measure of?
Why does the first ionization enthalpy of boron (Z = 5) decrease compared to that of beryllium (Z = 4)?
What is the unit of Ionization Enthalpy?
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What is the effect of shielding on ionization enthalpy down a group?
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What is the reaction that represents the first ionization enthalpy for an element X?
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What is the result of the increasing shielding effect down a group?
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What is the term for two or more species with the same number of electrons?
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What is electron gain enthalpy?
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What is the energy required to remove the second most loosely bound electron from an atom?
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What is the effect of nuclear charge on ionization enthalpy across a period?
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What is the physical state of the atom in the reaction that defines ionization enthalpy?
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Why does the ionization enthalpy of Al (Z = 13) decrease compared to that of Mg (Z = 12)?
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What is the general trend of ionization enthalpy down a group?
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Why do O2–, F–, Na+, and Mg2+ have different radii?
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What is the equation for the reaction that represents the second ionization enthalpy?
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What is the general trend of first ionization enthalpy as we go across a period?
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Why is the second ionization enthalpy higher than the first ionization enthalpy?
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What is the term 'ionization enthalpy' taken as, if not qualified?
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How does the first ionization enthalpy change as we descend a group?
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Why do elements with high reactivity tend to have low ionization enthalpies?
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Which of the following is NOT a trend in the variation of first ionization enthalpy with atomic number?
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Why is energy always required to remove electrons from an atom?
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What is the relationship between ionization enthalpy and atomic radius?
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Study Notes
Isoelectronic Species
- Isoelectronic species are atoms and ions that contain the same number of electrons
- Examples of isoelectronic species include O2–, F–, Na+, and Mg2+, which all have 10 electrons
- Despite having the same number of electrons, isoelectronic species have different radii due to their different nuclear charges
Ionization Enthalpy
- Ionization enthalpy is a quantitative measure of an element's tendency to lose an electron
- It represents the energy required to remove an electron from an isolated gaseous atom in its ground state
- The unit of ionization enthalpy is kJ mol–1
- The first ionization enthalpy is the energy required to remove the first electron from an atom
- The second ionization enthalpy is the energy required to remove the second electron from an atom, and so on
- Ionization enthalpy is always positive because energy is required to remove electrons from an atom
- The second ionization enthalpy is higher than the first ionization enthalpy because it is more difficult to remove an electron from a positively charged ion
Variation of Ionization Enthalpy with Atomic Number
- The first ionization enthalpies of elements up to atomic number 60 are plotted in Fig. 3.5
- The graph shows a periodic trend, with maxima at certain points
- Ionization enthalpy generally increases as you go across a period and decreases as you go down a group
- This is because the outermost electrons are held more and more tightly as you go across a period, and are increasingly farther from the nucleus as you go down a group
Electron Gain Enthalpy
- Electron gain enthalpy is the energy change accompanying the addition of an electron to a neutral gaseous atom to form an anion
- It provides a measure of the ease with which an atom adds an electron to form an anion
- The unit of electron gain enthalpy is also kJ mol–1
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Description
This quiz covers the concept of isoelectronic species and ionization enthalpy in chemistry. It explains how atoms and ions with the same number of electrons are classified as isoelectronic species and how ionization enthalpy measures the tendency of an element to lose electrons.
