Problem 75 - General Chemistry: Principles and Modern Applications

Question

On the basis of the periodic table and rules for electron configurations, indicate the number of (a) \(2 p\) electrons in \(\mathrm{N} ;\) (b) \(4 \mathrm{s}\) electrons in \(\mathrm{Rb} ;\) (c) \(4 \mathrm{d}\) electrons in As; (d) \(4 f\) electrons in \(\mathrm{Au} ;\) (e) unpaired electrons in \(\mathrm{Pb} ;\) (f) elements in group 14 of the periodic table; (g) elements in the sixth period of the periodic table.

Step-by-Step Solution

Answer

a) Nitrogen has 3 electrons in the \(2p\) orbital. b) Rubidium has 2 electrons in the \(4s\) orbital. c) Arsenic has no \(4d\) electrons. d) Gold has 14 electrons in the \(4f\) orbital. e) Lead has 2 unpaired electrons. f) There are 5 elements in group 14 of the periodic table. g) There are 32 elements in the sixth period of the periodic table.

Step 1: Understanding Electron Configuration

The electron configuration of an element in the periodic table is determined by its atomic number. For example, for Nitrogen (\(N\)), which has an atomic number of 7, the electron configuration is \(1s^2 2s^2 2p^3\). This means there are 2 electrons in the \(1s\) orbital, 2 in the \(2s\) and 3 in the \(2p\) orbital.

Step 2: Determining Number of 2p Electrons in Nitrogen

From the electron configuration of Nitrogen, \(1s^2 2s^2 2p^3\), we can see that the \(2p\) subshell has 3 electrons.

Step 3: Determining Number of 4s Electrons in Rubidium

Rubidium (\(Rb\)) is number 37 on the periodic table. Its electron configuration is \(1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^1\). Note how there are 2 electrons in the \(4s\) subshell.

Step 4: Determining Number of 4d Electrons in Arsenic

Arsenic (\(As\)) is number 33 on the periodic table. Its electron configuration is \(1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^3\). It doesn't have \(4d\) electrons.

Step 5: Determining Number of 4f Electrons in Gold

Gold (\(Au\)) is number 79 on the periodic table. Its electron configuration is \(1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^2 4d^{10} 5p^6 6s^1 4f^{14} 5d^{10}\). From this, we can see that there are 14 electrons in the \(4f\) subshell.

Step 6: Determining Number of Unpaired Electrons in Lead

Lead (\(Pb\)) is number 82 on the periodic table. Its electron configuration ends in \(6p^2\) which means there are 2 unpaired electrons in the outermost \(p\) subshell.

Step 7: Determining Elements in Group 14 of the Periodic Table

Elements in group 14 of the periodic table are Carbon (\(C\)), Silicon (\(Si\)), Germanium (\(Ge\)), Tin (\(Sn\)), and Lead (\(Pb\)).

Step 8: Determining Elements in the Sixth Period of the Periodic Table

The sixth period of the periodic table has 32 elements, starting from Cesium (\(Cs\)) up to Radon (\(Rn\)).

Key Concepts

Periodic Table

The periodic table is an arrangement of all known chemical elements organized by increasing atomic number. The layout of the periodic table allows us to easily determine various properties of elements, such as their electron configuration, reactivity, and group characteristics. Elements are arranged in horizontal rows known as periods, and vertical columns known as groups or families. Each element's position in the table can provide a lot of information, such as the number of electron shells and valence electrons, which are crucial in determining how elements interact with each other.
For example:

• Period - indicates the number of electron shells
• Group - elements in the same group have similar chemical properties due to having the same number of valence electrons
• Atomic number - represents the number of protons in an atom, usually also the number of electrons in a neutral atom

Using the periodic table, we can quickly find an element's electron configuration, helping to predict its chemical behavior.

Nitrogen

Nitrogen, with the chemical symbol \(N\), is a nonmetal located in group 15 of the periodic table. It has an atomic number of 7, which means it has 7 protons and, in a neutral atom, 7 electrons. The electron configuration of nitrogen is \(1s^2 2s^2 2p^3\). This configuration shows that nitrogen has two electrons in the first shell (1s) and five electrons in the second shell (2s and 2p), with the \(2p\) subshell holding three electrons.
Nitrogen is essential for life, being a primary component of amino acids and nucleic acids. It is a diatomic molecule in its natural form, existing primarily as \(N_2\), a colorless and odorless gas. Understanding nitrogen's electron configuration helps explain its ability to form strong bonds, like triple bonds seen in \(N_2\), contributing to its stability and prevalence as a key atmospheric component.

Rubidium

Rubidium, symbolized as \(Rb\), is an alkali metal situated in group 1 of the periodic table, sharing properties with other group 1 elements like lithium and sodium. Its atomic number is 37, indicating it has 37 protons and electrons. The electron configuration of rubidium is \(1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^1\). In this configuration, rubidium's outermost electron is in the 5s orbital, making it highly reactive and eager to lose this single electron to achieve a stable noble gas configuration.
Rubidium is known for its high reactivity, especially with water, where it reacts violently, producing heat, hydrogen gas, and rubidium hydroxide (RbOH). This reactivity is typical for alkali metals and reflects its position in the periodic table, where the lone electron in its outer shell drives its chemical interactions.

Lead

Lead, represented by the symbol \(Pb\), is a heavy metal found in group 14 of the periodic table, alongside elements like carbon and silicon. It has an atomic number of 82, corresponding to 82 protons and electrons. The electron configuration of lead ends in \(6p^2\), indicating the presence of two unpaired electrons in the 6p orbital. This configuration is characteristic of p-block elements, influencing lead's chemical properties and bonding.Lead is known for its density and malleability, playing significant roles in industries and applications, albeit with careful handling due to its toxicity. It has been used in batteries, construction, and protective shielding against radiation. Understanding lead's electron configuration helps reveal its capability for forming various oxidation states, typically +2 and +4, in its compounds, highlighting its versatile nature despite the health risks associated with its use.