Question

In Table \(7.8\), the bonding atomic radius of neon is listed as \(0.58\) \(\AA\), whereas that for xenon is listed as \(1.40 \AA\). A classmate of yours states that the value for Xe is more realistic than the one for Ne. Is she correct? If so, what is the basis for her statement?

Short answer

The classmate's statement is valid. The bonding atomic radius of xenon is more realistic than the one for neon because xenon can form compounds, so it is easier to obtain a precise value based on experimental measurements. In contrast, neon rarely forms covalent bonds and has limited experimental data available, making it difficult to obtain a realistic bonding atomic radius. Moreover, the periodic trend shows that the atomic radius increases as we move down the columns, so xenon's larger bonding atomic radius is expected due to its lower position in the periodic table with additional electron shells.

Step-by-step solution

Understanding what bonding atomic radius is

Bonding atomic radius is the measure of the size of an atom when it forms a covalent bond with another atom. It can be determined experimentally by measuring the distance between the nuclei of two atoms in a chemical bond and dividing that value by 2.

Comparing the bonding atomic radii of neon and xenon

The bonding atomic radius for neon (Ne) is given as \(0.58 \, \AA\), and for xenon (Xe) it is \(1.40 \, \AA\). We are to determine whether the value for xenon is more realistic than the one for neon.

Analyzing the position of neon and xenon in the periodic table

Neon and xenon are both noble gases, belonging to Group 18 in the periodic table. Neon is in the 2nd period, and xenon is in the 5th period. As we move down the columns in the periodic table, the size of elements generally increases. This is mainly due to the addition of electrons in new energy levels, which causes the atomic radius to increase due to the increased shielding effect and electron-electron repulsion.

Assessing the validity of the statement

Based on the periodic trend discussed in Step 3, we can say that xenon should indeed have a larger bonding atomic radius than neon due to it being in a lower period with additional electron shells. However, to assess the validity of the statement, we also need to consider the type of bonds formed by both elements and their scarcity in nature. Neon is a noble gas that rarely forms any bonds, including covalent bonds, due to its full electron configuration. Therefore, assigning a bonding atomic radius to neon is challenging, as there are few or no compounds for experimental measurements. This is likely what the classmate's statement is based on since there is little experimental data available for the bonding atomic radius of neon, making it difficult to obtain a "realistic" value. Xenon, on the other hand, can form compounds, although they are rare. Some xenon compounds, such as XeF₂ and XeF₄, are known and have been studied. Consequently, it is more feasible to derive a bonding atomic radius value for xenon based on experimental measurements.

Concluding the validity of the statement

Based on the analysis above, the classmate's statement can be considered valid. The bonding atomic radius of xenon is more realistic in the sense that it is easier to obtain a precise value due to the availability of compounds and experimental data. The bonding atomic radius of neon is more challenging to obtain because it rarely forms covalent bonds and there is limited experimental data available.

Key concepts

Noble Gases

Noble gases belong to Group 18 of the periodic table. This unique group of elements includes helium, neon, argon, krypton, xenon, and radon. They are characterized by their full valence electron shell, which typically makes these gases chemically inert. Due to their lack of reactivity, noble gases tend to remain isolated rather than forming compounds, which poses a challenge for experimental measurements and data collection.
Compounds are scarce for most noble gases because forming covalent bonds would disrupt their stable electron configuration. However, under certain conditions, some heavier gases like xenon are capable of forming bonds. This intriguing behavior of xenon allows scientists to measure its bonding atomic radius effectively.
Neon, on the other hand, remains largely unreactive and typically does not form compounds, thus making it challenging to obtain experimental values like the bonding atomic radius. Understanding the behavior of noble gases helps underpin their rarity in chemical reactions and influences how we measure and interpret their physical properties.

Periodic Table Trends

The periodic table organizes elements into columns called groups and rows known as periods, revealing patterns in electronic structure and properties. One key trend is the change in atomic size observed as you move across each period and down each group. Generally, atomic radius decreases across a period from left to right due to increased nuclear charge, which pulls electrons closer to the nucleus.
Conversely, atomic radius increases as we move down a group. This increase is primarily due to the addition of electron shells, which outweighs the increase in nuclear charge. In the context of noble gases, xenon has a much larger atomic radius than neon due to its position in the fifth period compared to neon's second period.

Covalent Bonds

Covalent bonds involve the sharing of electron pairs between atoms, which leads to stability as atoms achieve a full valence shell configuration. These bonds are essential for measuring the bonding atomic radius, since this measurement represents half the distance between the nuclei of two bonded atoms.
However, noble gases typically have a complete electron valence shell, making them uninterested in forming covalent bonds without sufficient external energy. Xenon stands out because it can form compounds like XeF₂ and XeF₄ under specific conditions. This capability to engage in covalent bonding allows for experimental determination of bonding atomic radii. In contrast, neon's lack of bonding limits the available experimental data for determining its bonding atomic radius.

Experimental Data in Atomic Measurements

Experimental data is critical for accurately determining atomic properties like bonding atomic radius. This data is usually derived from measuring physical quantities in chemical bonds, like the distance between atomic nuclei. Such precise measurements are made possible only when compounds exist to study.
For instance, xenon forms a few compounds, allowing scientists to measure its atomic radius reliably. Consequently, obtaining an accurate measure of xenon's bonding atomic radius is feasible, supported by substantial experimental data.
Neon's challenge lies in the scarcity of compounds it forms due to its complete electron shell. With limited bonding occurrences, experimental data for neon's atomic radius comes from indirect methods or theoretical calculations, introducing more uncertainty and making the value less "realistic" compared to xenon. Understanding this context is crucial in assessing the accuracy and reliability of bonding atomic radius data for different elements.