Problem 9
Question
Lithium hydride could be written as either \(\mathrm{Li}^{\oplus}: \mathrm{H}^{\ominus}\) or \(\mathrm{H}^{\oplus}: \mathrm{Li}^{\ominus}\) depending on whether lithium or hydrogen is more electron-attracting. Explain why hydrogen is actually more electron-attracting, making the correct structure \(\mathrm{Li}^{\oplus}: \mathrm{H}^{\ominus}\).
Step-by-Step Solution
Verified Answer
Hydrogen is more electron-attracting than lithium, forming \\( \mathrm{Li}^{\oplus}: \mathrm{H}^{\ominus} \\).
1Step 1: Understand Electronegativity
Electronegativity is the ability of an atom to attract shared electrons in a chemical bond. The higher the electronegativity, the stronger the pull it exerts on the electrons.
2Step 2: Compare Electronegativity of Lithium and Hydrogen
Look at the periodic table to evaluate the electronegativity of lithium (Li) and hydrogen (H). Lithium, which is located in Group 1, has a lower electronegativity compared to hydrogen, which is located in Group 1 but further to the right.
3Step 3: Determine Polarity Based on Electronegativity
Because hydrogen has a higher electronegativity than lithium, electrons in the \( \mathrm{Li}^{\oplus}: \mathrm{H}^{\ominus} \) bond are more attracted to hydrogen. This makes hydrogen partially negative and lithium partially positive.
4Step 4: Confirm the Correct Structure
Based on the electronegativity difference, the correct structure of lithium hydride is \( \mathrm{Li}^{\oplus}: \mathrm{H}^{\ominus} \), indicating that lithium donates an electron to hydrogen, forming a polar covalent bond where H is negatively charged.
Key Concepts
Periodic TableChemical Bond PolarityElectronegativity Comparison
Periodic Table
The periodic table is an essential tool for understanding the elements and their properties. It is organized so that elements with similar chemical characteristics are grouped together, usually aligning within the same columns known as groups or families.
The position of an element in the periodic table can give insight into its electron configuration and electronegativity, which is a measure of an atom's ability to attract electrons. A very handy way to quickly grasp the basic properties of elements is by examining their location on the table. For instance, elements on the left side tend to be metals and often have lower electronegativity values, while non-metals, such as those found on the right side (and hydrogen), generally have higher electronegativities. Take for example lithium (Li) and hydrogen (H). Lithium, a metal located in the alkali metal group, is placed on the far left of the table. Contrarily, hydrogen, though also in Group 1, is situated further to the right and has non-metal characteristics, reflective of a relatively higher electronegativity. The periodic table not only tells us about the element's electronegativity but also briefly elucidates its bonding tendencies.
The position of an element in the periodic table can give insight into its electron configuration and electronegativity, which is a measure of an atom's ability to attract electrons. A very handy way to quickly grasp the basic properties of elements is by examining their location on the table. For instance, elements on the left side tend to be metals and often have lower electronegativity values, while non-metals, such as those found on the right side (and hydrogen), generally have higher electronegativities. Take for example lithium (Li) and hydrogen (H). Lithium, a metal located in the alkali metal group, is placed on the far left of the table. Contrarily, hydrogen, though also in Group 1, is situated further to the right and has non-metal characteristics, reflective of a relatively higher electronegativity. The periodic table not only tells us about the element's electronegativity but also briefly elucidates its bonding tendencies.
Chemical Bond Polarity
Chemical bond polarity arises when there is an uneven distribution of electrons between the atoms forming a bond. This happens when the atoms involved have different electronegativities, causing the electrons to be pulled more towards one atom.
In a polar bond, one end becomes slightly negative ( ext{-} ) and the other end slightly positive ( ext{+} ). Such polarity can influence the physical properties and reactivities of the molecules. For example, in the case of lithium hydride ( ext{LiH} ), because hydrogen has a higher electronegativity compared to lithium, the bond is polar with electrons drawn more towards hydrogen.
This characteristic of polar bonds is critical to predicting how molecules will interact. It explains phenomena like solubility in water, dipole moments, and even reaction mechanisms. Understanding the concept of bond polarity is thus pivotal in chemistry as it explains so much about molecule behavior. By discerning electric charge distribution, one can easily predict potential molecular interactions.
In a polar bond, one end becomes slightly negative ( ext{-} ) and the other end slightly positive ( ext{+} ). Such polarity can influence the physical properties and reactivities of the molecules. For example, in the case of lithium hydride ( ext{LiH} ), because hydrogen has a higher electronegativity compared to lithium, the bond is polar with electrons drawn more towards hydrogen.
This characteristic of polar bonds is critical to predicting how molecules will interact. It explains phenomena like solubility in water, dipole moments, and even reaction mechanisms. Understanding the concept of bond polarity is thus pivotal in chemistry as it explains so much about molecule behavior. By discerning electric charge distribution, one can easily predict potential molecular interactions.
Electronegativity Comparison
Electronegativity comparison involves analyzing the ability of different elements to attract electrons within a bond. Electronegativity values increase from left to right across a period on the periodic table and decrease from top to bottom down a group.
In the case of lithium (Li) versus hydrogen (H), the electronegativity of lithium is lower than that of hydrogen. Hydrogen holds a greater electronegativity value, which implies that it can attract bonding electrons more effectively than lithium. This is why in compounds like ext{LiH} , hydrogen almost always attracts electrons more than lithium does.
Understanding these comparisons helps for predicting the resultant charge distribution in a molecule and helps in determining the bond's ionic or covalent nature. Electronegativity comparisons are fundamental for understanding how atoms interact during chemical reactions and what kind of bond is formed.
In the case of lithium (Li) versus hydrogen (H), the electronegativity of lithium is lower than that of hydrogen. Hydrogen holds a greater electronegativity value, which implies that it can attract bonding electrons more effectively than lithium. This is why in compounds like ext{LiH} , hydrogen almost always attracts electrons more than lithium does.
Understanding these comparisons helps for predicting the resultant charge distribution in a molecule and helps in determining the bond's ionic or covalent nature. Electronegativity comparisons are fundamental for understanding how atoms interact during chemical reactions and what kind of bond is formed.
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