Textbook Question
Based on their positions in the periodic table, predict which atom of the following pairs will have the smaller first ionization energy: (a) Br, Kr (b) C, Ca (c) Li, Rb (d) S, Ge (e) Al, B.
Ch.7 - Periodic Properties of the Elements
Chapter 7, Problem 46
Identify each statement as true or false.
a. Ionization energies are always negative quantities.
b. Oxygen has a larger first ionization energy than fluorine.
c. The second ionization energy of an atom is always greater than its first ionization energy.
d. The third ionization energy is the energy needed to ionize three electrons from a neutral atom.
Verified step by step guidance1
Ionization energy is the energy required to remove an electron from an atom or ion. It is always a positive quantity because energy must be supplied to overcome the attraction between the electron and the nucleus. Therefore, statement a is false.
The first ionization energy generally increases across a period from left to right due to increasing nuclear charge. Since fluorine is to the right of oxygen in the periodic table, fluorine has a larger first ionization energy than oxygen. Therefore, statement b is false.
The second ionization energy is the energy required to remove a second electron after the first has been removed. It is always greater than the first ionization energy because the electron is being removed from a positively charged ion, which has a stronger attraction to the remaining electrons. Therefore, statement c is true.
The third ionization energy refers to the energy required to remove a third electron after the first two have been removed, not the energy needed to remove three electrons simultaneously. Therefore, statement d is false.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Ionization Energy
Ionization energy is the energy required to remove an electron from a gaseous atom or ion. It is always a positive value because energy must be supplied to overcome the attraction between the negatively charged electron and the positively charged nucleus. Therefore, the statement that ionization energies are always negative is false.
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Trends in Ionization Energy
Ionization energy generally increases across a period in the periodic table due to increasing nuclear charge, which holds electrons more tightly. Conversely, it decreases down a group as additional electron shells are added, increasing distance from the nucleus. Thus, the statement regarding oxygen having a larger first ionization energy than fluorine is false, as fluorine has a higher ionization energy.
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Successive Ionization Energies
Successive ionization energies refer to the energy required to remove additional electrons from an atom after the first has been removed. Typically, each successive ionization energy is greater than the previous one due to increased positive charge in the nucleus and reduced electron-electron repulsion. Therefore, the statement that the second ionization energy is always greater than the first is true, while the statement about the third ionization energy is misleading, as it refers to the energy needed to remove three electrons, not just the third ionization energy itself.
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Related Practice
Textbook Question
Write equations that show the process for a. the first two ionization energies of lead and b. the fourth ionization energy of zirconium.
Textbook Question
Which element has the highest second ionization energy: Li, K, or Be?
Textbook Question
Pick the correct word to complete the sentence: The larger the atom, the (smaller/larger) its first ionization energy.
Textbook Question
Which element in the periodic table has the largest first ionization energy?