Question

Refer to the periodic table and write the predicted electron configuration for each of the following elements using core notation: (a) W (b) Bi (c) \(\mathrm{Ra}\) (d) \(A C\)

Short answer

(a) \([\text{Xe}]6s^24f^{14}5d^4\); (b) \([\text{Xe}]6s^24f^{14}5d^{10}6p^3\); (c) \([\text{Rn}]7s^2\); (d) \([\text{Rn}]7s^26d^1\).

Step-by-step solution

Understand Core Notation

In core notation, we start with the electron configuration of the nearest noble gas with fewer electrons, and then add the remaining electrons to describe the configuration of the desired element. This simplifies the notation by expressing electrons up to the noble gas in a condensed form.

Identify Nearest Noble Gas for Tungsten (W)

Tungsten (W) is element 74. The nearest noble gas that comes before tungsten is Xenon (Xe), which is element 54. Therefore, the core configuration for tungsten will start with \([\text{Xe}]\).

Write Electron Configuration for Tungsten (W)

Tungsten is in the 6th period and belongs to the d-block. After xenon, the sequence continues with \(6s^2\), \(4f^{14}\), and then \(5d^4\). So the configuration is: \([\text{Xe}]6s^24f^{14}5d^4\).

Identify Nearest Noble Gas for Bismuth (Bi)

Bismuth (Bi) is element 83. Like tungsten, it follows Xenon (Xe) on the periodic table because Xe is element 54. Thus, Bi's core notation starts with \([\text{Xe}]\).

Write Electron Configuration for Bismuth (Bi)

Following Xenon, you proceed through the 6s, 4f, and 5d blocks. After the \(4f^{14}\) and \(5d^{10}\), the configuration reaches the 6p block with \(6p^3\). The full configuration is: \([\text{Xe}]6s^24f^{14}5d^{10}6p^3\).

Identify Nearest Noble Gas for Radium (Ra)

Radium (Ra) is element 88. The closest noble gas before radium is Radon (Rn), which is element 86. Thus, its core notation starts with \([\text{Rn}]\).

Write Electron Configuration for Radium (Ra)

Following Radon, the sequence is \(7s^2\) for Radium as it is in the S-block of the 7th period. Therefore, the configuration is: \([\text{Rn}]7s^2\).

Identify Nearest Noble Gas for Actinium (Ac)

Actinium (Ac) is element 89. The nearest noble gas preceding it is also Radon (Rn), element 86, making \([\text{Rn}]\) the starting point for its configuration.

Write Electron Configuration for Actinium (Ac)

Beyond Radon, Actinium follows straight into the 7th period with \(7s^2\) and adds one electron to the \(6d\) sublevel, giving the configuration: \([\text{Rn}]7s^26d^1\).

Key concepts

Periodic Table

The periodic table is an organized chart that displays all known chemical elements. It arranges elements in order of increasing atomic number. This arrangement helps due to similar properties arising periodically as you move across the table. Elements within the same column, known as groups, share similar chemical behaviors, while rows, known as periods, indicate repeating patterns.

• Elements are located based on their atomic number, electron configurations, and recurring chemical properties.
• Periods indicate increasing energy levels of electrons within atoms.
• Groups, or families, have elements with similar valence electron configurations, which results in similar chemical properties.

The periodic table is essential not only because it categorizes elements, but it also predicts chemical reactions and helps in understanding chemical behavior in various conditions. By understanding an element's position, you can easily predict its chemical properties.

Core Notation

Core notation simplifies the way we write electron configurations for elements. It utilizes the electron configuration of the nearest preceding noble gas to abbreviate notation. This method simplifies the depiction of an element’s occupied electron shells, making it quicker and easier to understand complex electron arrangements.

• First, identify the noble gas that comes before the element in question. This noble gas acts as the 'core' or condensed representation of electrons.
• Only the electron configuration beyond this noble gas is written in detail, showing additional electrons added sequentially to this core.

For example, considering the element Tungsten (W), its electron configuration starts with \([\text{Xe}]\) because Xenon is the nearest noble gas before Tungsten. This concise method drastically reduces the complexity of visualizing electron configurations of heavier elements.

Noble Gases

Noble gases are a group of chemically inert elements that occupy Group 18 of the periodic table. These gases, namely Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), and Radon (Rn), are known for their lack of reactivity.

• Their non-reactivity is attributed to having complete outer electron shells, making them stable.
• Noble gases play a crucial role in electron configuration, acting as reference points or benchmarks for core notation.

The complete valence shell of noble gases means they have little tendency to participate in chemical reactions. This non-reactivity is why their electron configurations make excellent shortcuts in core notation, simplifying the representation of many elements on the periodic table.

D-block Elements

D-block elements are found in the central part of the periodic table, comprising groups 3 through 12. These elements are known as transition metals and have partially filled d orbitals.

• They are characterized by complex electron configurations that often involve the filling of d orbitals.
• The standard electron configuration pattern for these elements is adding electrons to the d sublevel, after filling the s sublevel of the previous period.

Transition metals are known for their shiny appearance and excellent conductivity. They frequently exhibit variable oxidation states, which is a distinct property resulting from the involvement of d electrons in bond formations. For example, Tungsten (W), a d-block element, has the configuration \([\text{Xe}]6s^24f^{14}5d^4\) emphasizing the addition of d-electrons.
Their unique properties and complex electron configurations make d-block elements vital in various industrial and chemical applications.