Question

Using spdf and noble gas notations, write electron configurations for atoms of the following elements. (Try to do this by looking at the periodic table but not at Table \(7.3 .\) ) (a) Strontium, Sr. This element is named for a town in Scotland. (b) Zirconium, Zr. The metal is exceptionally resistant to corrosion and so has important industrial applications. Moon rocks show a surprisingly high zirconium content compared with rocks on Earth. (c) Rhodium, Rh. This metal is used in jewelry and in catalysts in industry. (d) Tin, Sn. The metal was used in the ancient world. Alloys of tin (solder, bronze, and pewter) are important.

Short answer

(a) Strontium: [Kr] 5s²; (b) Zirconium: [Kr] 5s² 4d²; (c) Rhodium: [Kr] 5s¹ 4d⁸; (d) Tin: [Kr] 5s² 4d¹⁰ 5p².

Step-by-step solution

Understanding Electron Configuration

Electron configuration describes the distribution of electrons in an atom's orbitals. The notation normally starts with the lowest energy level and fills subsequential orbitals following the Aufbau principle, Hund's rule, and the Pauli Exclusion Principle.

Use of Noble Gas Notation

Noble gas notation simplifies the electron configuration by using the symbol of a noble gas to represent filled inner electron shells.

Electron Configuration for Strontium (Sr)

Strontium is the 38th element on the periodic table. Its electron configuration using spdf notation is ":[Kr] 5s^2." This configuration shows it follows Krypton (Kr), which has a filled electron shell.

Electron Configuration for Zirconium (Zr)

Zirconium is element 40. Its electron configuration is ":[Kr] 5s^2 4d^2." Following Krypton again, the next filled orbitals include the 5s and partially filled 4d.

Electron Configuration for Rhodium (Rh)

Rhodium is element 45. Its electron configuration is ":[Kr] 5s^1 4d^8." After filling the 5s, electrons continue into the 4d, resulting in one unpaired electron in 5s.

Electron Configuration for Tin (Sn)

Tin is element 50. Its electron configuration is ":[Kr] 5s^2 4d^10 5p^2." After completing the 4d subshell with 10 electrons, it continues to fill the 5p with 2 electrons.

Key concepts

Noble Gas Notation

Noble gas notation is a convenient method for writing electron configurations. It involves using the electron configuration of the nearest noble gas to simplify the notation of the inner-shell electrons. For example:

• Instead of writing all the inner electron configurations, we use the noble gas symbol in brackets.
• For Strontium (Sr), which is element 38, we start with Krypton (Kr) as it is the preceding noble gas.
• This results in the notation ": [Kr] 5s^2," where only the outer electrons beyond Krypton's configuration are shown.

This method makes it easier to identify and focus on the valence electrons, which are crucial for understanding an element’s chemical behavior.

Aufbau Principle

The Aufbau principle is fundamental for determining the electron configuration of an element. It dictates the order in which electrons fill subshells and orbitals, based on the increasing energy levels:

• Electrons occupy the lowest energy orbitals first before moving to higher ones.
• This principle is a guide to predict and remember the structure of electron configurations.
• Using this principle, you fill the 1s orbital first, then move to 2s, 2p, 3s, and so forth, following the sequence dictated by their energy levels.

For elements like Zirconium (Zr), with configurations such as "[Kr] 5s^2 4d^2," it highlights how electrons are added progressively, maintaining energy efficiency.

Periodic Table

The periodic table is a vital tool for understanding and predicting the electron configurations of elements. It is arranged in a manner that showcases recurring 'periodic' trends in element properties:

• Each row, or period, in the table represents the filling of a certain electron shell.
• Moving from left to right across a period, electrons add sequentially to the outermost shell.
• This helps in identifying the correct sequence of electron configurations for elements such as Rhodium (Rh), which is element 45 and located in the transition metals section.

The layout of the periodic table reflects the repeating pattern of electron filling sequences, resulting in similar properties among elements in the same column or group.

Pauli Exclusion Principle

The Pauli Exclusion Principle is key to understanding how electrons are arranged within an atom's electron shell.

Electron Configuration

Electron configuration describes the distribution of electrons in an atom's orbitals.