(1) Write the electronic configuration of an element with atomic mass of 17.
(2) What will be the electronic configuration of the following positive charge ions: [tex]$K ^{+}, Cl ^{2+}, Al ^{3+}$[/tex]?
(3) What will be the electronic configuration of the following negatively charge ions: [tex]$Cl ^{-}, I ^{-}, Br ^{-}, O ^{2-}$[/tex]?

Chlorine (Cl) electronic configuration: 1 s 2 2 s 2 2 p 6 3 s 2 3 p 5 .
K + electronic configuration: 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 .
C l 2 + electronic configuration: 1 s 2 2 s 2 2 p 6 3 s 2 3 p 3 .
A l 3 + electronic configuration: 1 s 2 2 s 2 2 p 6 .
C l − electronic configuration: 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 .
I − electronic configuration: 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 4 s 2 3 d 10 4 p 6 5 s 2 4 d 10 5 p 6 .
B r − electronic configuration: 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 4 s 2 3 d 10 4 p 6 .
O 2 − electronic configuration: 1 s 2 2 s 2 2 p 6 .

Explanation

Introduction to Electronic Configuration Let's break down this problem step by step. We're going to determine the electronic configurations of several elements and ions. Remember that the electronic configuration describes how electrons are arranged in the different energy levels and sublevels within an atom or ion.

Electronic Configuration of Chlorine First, we need to identify the element with an atomic number of 17. This is chlorine (Cl). Now, let's write its electronic configuration. Chlorine has 17 electrons. The electronic configuration is 1 s 2 2 s 2 2 p 6 3 s 2 3 p 5 .

Electronic Configurations of Positive Ions Next, we'll determine the electronic configurations of the positive ions: K + , C l 2 + , and A l 3 + .



K + : Potassium (K) has an atomic number of 19, so its electronic configuration is 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 4 s 1 . When it becomes K + , it loses one electron from the outermost shell (4s). So, the electronic configuration of K + is 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 .
C l 2 + : Chlorine (Cl) has an electronic configuration of 1 s 2 2 s 2 2 p 6 3 s 2 3 p 5 . When it becomes C l 2 + , it loses two electrons from the outermost shell (3p). So, the electronic configuration of C l 2 + is 1 s 2 2 s 2 2 p 6 3 s 2 3 p 3 .
A l 3 + : Aluminum (Al) has an atomic number of 13, so its electronic configuration is 1 s 2 2 s 2 2 p 6 3 s 2 3 p 1 . When it becomes A l 3 + , it loses three electrons from the outermost shells (3s and 3p). So, the electronic configuration of A l 3 + is 1 s 2 2 s 2 2 p 6 .


Electronic Configurations of Negative Ions Now, let's determine the electronic configurations of the negative ions: C l − , I − , B r − , and O 2 − .


C l − : Chlorine (Cl) has an electronic configuration of 1 s 2 2 s 2 2 p 6 3 s 2 3 p 5 . When it becomes C l − , it gains one electron in the outermost shell (3p). So, the electronic configuration of C l − is 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 .
I − : Iodine (I) has an atomic number of 53, so its electronic configuration is 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 4 s 2 3 d 10 4 p 6 5 s 2 4 d 10 5 p 5 . When it becomes I − , it gains one electron in the outermost shell (5p). So, the electronic configuration of I − is 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 4 s 2 3 d 10 4 p 6 5 s 2 4 d 10 5 p 6 .
B r − : Bromine (Br) has an atomic number of 35, so its electronic configuration is 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 4 s 2 3 d 10 4 p 5 . When it becomes B r − , it gains one electron in the outermost shell (4p). So, the electronic configuration of B r − is 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 4 s 2 3 d 10 4 p 6 .
O 2 − : Oxygen (O) has an atomic number of 8, so its electronic configuration is 1 s 2 2 s 2 2 p 4 . When it becomes O 2 − , it gains two electrons in the outermost shell (2p). So, the electronic configuration of O 2 − is 1 s 2 2 s 2 2 p 6 .


Final Answer In summary, we have determined the electronic configurations of the given elements and ions. Remember that positive ions lose electrons, and negative ions gain electrons to achieve a stable electron configuration.

Examples
Understanding electronic configurations is crucial in chemistry. For example, knowing the electronic configuration of an atom helps predict how it will interact with other atoms to form chemical bonds. This knowledge is essential in designing new materials, understanding chemical reactions, and developing new technologies. For instance, in designing semiconductors, understanding the electronic configuration of silicon and other dopants is critical to controlling the flow of electricity. Similarly, in drug development, understanding how a drug molecule interacts with a target protein relies heavily on the electronic configurations of the atoms involved. The ability to predict and manipulate electronic configurations is a cornerstone of modern chemistry and materials science.

Answered by GinnyAnswer | 2025-07-08