Chapter 9: Problem 102
Based on periodic trends, which one of these elements would you expect to be most easily reduced: \(\mathrm{Ca}, \mathrm{Sr}, \mathrm{P}\), or \(\mathrm{Cl}\) ?
Short Answer
Expert verified
Chlorine (Cl) would be the most easily reduced element among the given options due to its high electron affinity and position in the periodic table.
Step by step solution
01
Understanding Reduction
Reduction in chemistry refers to the gain of electrons by an atom or ion. When an element is easily reduced, it readily gains electrons to form a negatively charged ion or anion. Elements that are easily reduced typically have high electron affinities, which means they have a strong attraction for additional electrons.
02
Analyzing Periodic Trends
Periodic trends suggest that nonmetals, which are found on the right side of the periodic table, generally have higher electron affinities than metals. Metals, on the left side, more readily lose electrons in chemical reactions (oxidation). Within a group of nonmetals in the periodic table, electron affinity tends to decrease as you move down the group. This is because the atoms become larger and the additional electrons are further from the nucleus, experiencing less electrostatic pull.
03
Comparing the Given Elements
Comparing the given elements: Ca and Sr are alkaline earth metals and tend to lose electrons rather than gain them. Phosphorus (P) is a nonmetal but is not as electronegative as the halogens. Chlorine (Cl), being a halogen and in the same period as Phosphorus, has a higher electron affinity and thus is more likely to gain electrons and be reduced.
04
Determining Which Element is Most Easily Reduced
Considering the periodic trends and the properties of the elements provided, Chlorine (Cl), is the element that would be expected to be most easily reduced because it has a high electron affinity and is positioned among the halogens, which are known for their readiness to gain electrons.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Electron Affinity
Electron affinity describes the amount of energy released when an atom in the gaseous state accepts an electron to form a negative ion. It is a key concept in understanding reduction behavior in elements. Higher electron affinity values indicate a larger amount of energy released and thus a stronger tendency of an atom to gain electrons.
As one navigates the periodic table from left to right, electron affinities generally increase. This trend is due to the increasing number of protons in the elements as you move across a period, leading to stronger attraction between the nucleus and the added electron. However, there are exceptions in this trend, such as the group of noble gases, which have a complete valence shell and do not easily gain electrons.
Within groups (the columns of the periodic table), electron affinity values tend to decrease as you move from the top to the bottom. This is because the outermost electrons are further away from the nucleus and are less attracted to it due to the increased atomic size and the inner-shell electron shielding effect.
Understanding electron affinity enables us to predict the ability of an element to gain electrons in a process known as reduction. Elements with higher electron affinities are generally more likely to be reduced in chemical reactions.
As one navigates the periodic table from left to right, electron affinities generally increase. This trend is due to the increasing number of protons in the elements as you move across a period, leading to stronger attraction between the nucleus and the added electron. However, there are exceptions in this trend, such as the group of noble gases, which have a complete valence shell and do not easily gain electrons.
Within groups (the columns of the periodic table), electron affinity values tend to decrease as you move from the top to the bottom. This is because the outermost electrons are further away from the nucleus and are less attracted to it due to the increased atomic size and the inner-shell electron shielding effect.
Understanding electron affinity enables us to predict the ability of an element to gain electrons in a process known as reduction. Elements with higher electron affinities are generally more likely to be reduced in chemical reactions.
Oxidation and Reduction
The concepts of oxidation and reduction are pivotal in understanding chemical reactions and are often summarized by the mnemonic 'OIL RIG', which stands for 'oxidation is loss, reduction is gain' of electrons. When an element undergoes oxidation, it loses electrons and typically forms a positively charged ion, or cation.
Oxidation and reduction always occur together; whenever one substance is oxidized, another is reduced in a process known as a redox reaction. This dual process reflects the transfer of electrons from one substance to another. The substance that gains electrons (and is reduced) has a higher electron affinity and is a stronger oxidizing agent because it 'pulls' electrons from the other substance.
The ability to identify what gets oxidized and what gets reduced in a reaction is key in predicting how reactants will change during a chemical process. Understanding the differences in electron affinities and the periodic trends can provide insight into these predictions. For instance, metals that tend to lose electrons easily are more likely to be oxidized, while nonmetals with high electron affinities are more likely to be reduced.
Oxidation and reduction always occur together; whenever one substance is oxidized, another is reduced in a process known as a redox reaction. This dual process reflects the transfer of electrons from one substance to another. The substance that gains electrons (and is reduced) has a higher electron affinity and is a stronger oxidizing agent because it 'pulls' electrons from the other substance.
The ability to identify what gets oxidized and what gets reduced in a reaction is key in predicting how reactants will change during a chemical process. Understanding the differences in electron affinities and the periodic trends can provide insight into these predictions. For instance, metals that tend to lose electrons easily are more likely to be oxidized, while nonmetals with high electron affinities are more likely to be reduced.
Periodic Table Groups
The periodic table is structured into rows called periods and columns known as groups. Each group contains elements with similar properties that often behave similarly in chemical reactions due to the configuration of their valence electrons.
For example, Group 1 elements, the alkali metals, have a single electron in their outermost shell, which they readily lose, becoming oxidized in reactions. As you move down Group 1, the reactivity of the elements increases, as those electrons are more easily lost due to increasing atomic size.
Conversely, Group 17, the halogens, have seven electrons in their valence shell, meaning they are one electron short of having the stable, full octet configuration of the noble gases in Group 18. The halogens have high electron affinities and are easily reduced in reactions as they gain that needed electron, becoming more stable. Within a group, the reactivity of nonmetals usually decreases as you go down the group since the additional electrons are further from the positively charged nucleus, as illustrated by the lower electron affinity of iodine compared to fluorine.
Understanding the behavior of elements within groups of the periodic table can therefore help us predict how an element is likely to react in terms of gaining or losing electrons and participating in oxidation or reduction reactions.
For example, Group 1 elements, the alkali metals, have a single electron in their outermost shell, which they readily lose, becoming oxidized in reactions. As you move down Group 1, the reactivity of the elements increases, as those electrons are more easily lost due to increasing atomic size.
Conversely, Group 17, the halogens, have seven electrons in their valence shell, meaning they are one electron short of having the stable, full octet configuration of the noble gases in Group 18. The halogens have high electron affinities and are easily reduced in reactions as they gain that needed electron, becoming more stable. Within a group, the reactivity of nonmetals usually decreases as you go down the group since the additional electrons are further from the positively charged nucleus, as illustrated by the lower electron affinity of iodine compared to fluorine.
Understanding the behavior of elements within groups of the periodic table can therefore help us predict how an element is likely to react in terms of gaining or losing electrons and participating in oxidation or reduction reactions.