Problem 68 - Chemistry: The Central Science

Question

Write the condensed electron configurations for the following atoms, and indicate how many unpaired electrons each has: (a) \(\mathrm{Ga}\), (b) \(\mathrm{Ca},(\mathrm{c}) \mathrm{V},(\mathrm{d}) \mathrm{I},(\mathrm{e}) \mathrm{Y}\), (f) \(\mathrm{Pt}\), (g) Lu.

Step-by-Step Solution

Answer

a) Ga: \([Ar] 3d^{10} 4s^2 4p^1\), 1 unpaired electron b) Ca: \([Ar] 4s^2\), 0 unpaired electrons c) V: \([Ar] 3d^3 4s^2\), 3 unpaired electrons d) I: \([Kr] 4d^{10} 5s^2 5p^5\), 1 unpaired electron e) Y: \([Kr] 4d^1 5s^2\), 1 unpaired electron f) Pt: \([Xe] 4f^{14} 5d^9 6s^1\), 1 unpaired electron g) Lu: \([Xe] 4f^{14} 5d^1 6s^2\), 1 unpaired electron

Step 1: Gallium(Ga) electron configuration

Gallium has 31 electrons, and its condensed electron configuration is \([Ar] 3d^{10} 4s^2 4p^1\). The last electron subshell is a 4p subshell, which has one unpaired electron. Therefore, Ga has 1 unpaired electron. (b)

Step 2: Calcium(Ca) electron configuration

Calcium has 20 electrons, and its condensed electron configuration is \([Ar] 4s^2\). The last electron subshell is a 4s subshell, which has no unpaired electrons. Therefore, Ca has 0 unpaired electrons. (c)

Step 3: Vanadium(V) electron configuration

Vanadium has 23 electrons, and its condensed electron configuration is \([Ar] 3d^3 4s^2\). The last electron subshell is a 3d subshell, which has three unpaired electrons. Therefore, V has 3 unpaired electrons. (d)

Step 4: Iodine(I) electron configuration

Iodine has 53 electrons, and its condensed electron configuration is \([Kr] 4d^{10} 5s^2 5p^5\). The last electron subshell is a 5p subshell, which has one unpaired electron. Therefore, I has 1 unpaired electron. (e)

Step 5: Yttrium(Y) electron configuration

Yttrium has 39 electrons, and its condensed electron configuration is \([Kr] 4d^1 5s^2\). The last electron subshell is a 4d subshell, which has one unpaired electron. Therefore, Y has 1 unpaired electron. (f)

Step 6: Platinum(Pt) electron configuration

Platinum has 78 electrons, and its condensed electron configuration is \([Xe] 4f^{14} 5d^9 6s^1\). The last electron subshell is a 5d subshell, which has one unpaired electron. Therefore, Pt has 1 unpaired electron. (g)

Step 7: Lutetium(Lu) electron configuration

Lutetium has 71 electrons, and its condensed electron configuration is \([Xe] 4f^{14} 5d^1 6s^2\). The last electron subshell is a 5d subshell, which has one unpaired electron. Therefore, Lu has 1 unpaired electron.

Key Concepts

Unpaired Electrons

Understanding the concept of unpaired electrons is essential in the study of chemistry, particularly in explaining the magnetic properties and reactivity of elements. Unpaired electrons are those that occupy an atomic or molecular orbital alone. Since electrons are negatively charged and repel each other, they tend to pair up to maintain a more stable arrangement. However, certain electron configurations can lead to the presence of unpaired electrons.

In our textbook exercise, elements like Gallium (Ga), Iodine (I), Yttrium (Y), Platinum (Pt), and Lutetium (Lu) all exhibited a single unpaired electron in their outermost subshells. This lone electron creates what chemists refer to as a 'paramagnetic' property, meaning that in the presence of an external magnetic field, these elements will be weakly attracted to it. On the other hand, Calcium (Ca) showed no unpaired electrons in its electron configuration, leading to 'diamagnetic' properties, having no attraction to a magnetic field.

Electron Subshells

Electron subshells are divisions within an electron shell, and they determine the shape and energy of orbitals in which the electrons reside. The primary subshells are denoted by the letters s, p, d, and f, each having a characteristic shape and maximum number of electrons. The s subshell holds a maximum of 2 electrons, p holds 6, d holds 10, and f holds 14. The way these subshells are filled is governed by the Aufbau principle, which states that electrons occupy orbitals starting with the lowest energy level first.

For example, Calcium (Ca) ends with the 4s subshell completely filled, whereas Vanadium (V) contains three unpaired electrons in the 3d subshell. The number and arrangement of electrons in these subshells are crucial in determining the chemical behavior of an element. Subshells closest to the nucleus fill first; however, since energy levels can overlap, you may find elements like Chromium (Cr) and Copper (Cu) that have seeming anomalies in their electron configurations due to the energies of subshells being very close.

Periodic Table Elements

The periodic table is a systematic arrangement of elements based on their atomic number, electron configurations, and recurring chemical properties. Elements are organized into periods (rows) and groups (columns) and can be categorized into various blocks such as s, p, d, and f, which correspond to the type of subshell that is being filled with electrons.

Understanding the placement of an element on the periodic table can give insights into its electron configuration. For instance, Gallium (Ga) and Calcium (Ca) fall into different groups, indicating they have different valence electron structures, which contribute to their distinct chemical properties. Elements are also grouped into metals, nonmetals, and metalloids based on their physical and chemical characteristics. Metals tend to lose electrons and form cations, while nonmetals tend to gain electrons and form anions. The knowledge of where an element lies on the periodic table can significantly aid in predicting its reactivity, the types of bonds it forms, and its role in chemical compounds.