Use the periodic table to write the electron configuration of selenium (Se). Place the sublevels in order of filling from least energy to most energy.
Answer (1)
Determine the order of filling electron subshells based on the Aufbau principle.
Fill each subshell with the appropriate number of electrons until the total matches Selenium's atomic number (34).
Write the electron configuration as 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 4 s 2 3 d 10 4 p 4 .
The electron configuration of Selenium (Se) is 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 4 s 2 3 d 10 4 p 4 .
Explanation
Problem Analysis We want to determine the electron configuration of Selenium (Se) using the periodic table. Selenium has an atomic number of 34, which means a neutral selenium atom has 34 electrons. We need to fill the electron shells and subshells in order of increasing energy according to the Aufbau principle.
Aufbau Principle The Aufbau principle states that electrons first fill the lowest energy levels. The order of filling is: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p. Each s subshell can hold up to 2 electrons, each p subshell can hold up to 6 electrons, and each d subshell can hold up to 10 electrons.
Filling Subshells We start filling the subshells:
1 s 2 (2 electrons)
2 s 2 (2 electrons)
2 p 6 (6 electrons)
3 s 2 (2 electrons)
3 p 6 (6 electrons)
4 s 2 (2 electrons)
3 d 10 (10 electrons)
4 p 4 (4 electrons) Adding the number of electrons: 2 + 2 + 6 + 2 + 6 + 2 + 10 + 4 = 34 . This matches the atomic number of Selenium.
Final Configuration Therefore, the electron configuration of Selenium (Se) is 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 4 s 2 3 d 10 4 p 4 .
Examples
Understanding electron configurations helps predict how elements will interact to form chemical bonds. For example, knowing Selenium's electron configuration allows us to understand its bonding behavior with other elements, which is crucial in designing new materials or understanding chemical reactions. This knowledge is fundamental in fields like materials science, chemistry, and electronics, where the properties of substances are directly related to their electronic structure.
