The number of valence electrons in an element with electron configuration [tex]$1 s^2 2 s^2 2 p^6 3 s^2 3 p^4$[/tex] is
A. 6
B. 8
C. 4
D. 2
E. 16
Answer (1)
Identify the valence shell as the outermost shell (n=3).
Count the electrons in the 3s subshell (2 electrons) and the 3p subshell (4 electrons).
Add the number of electrons in the 3s and 3p subshells: 2 + 4 = 6 .
The number of valence electrons is 6 .
Explanation
Understanding the Problem The electron configuration of the element is given as 1 s 2 2 s 2 2 p 6 3 s 2 3 p 4 . We need to find the number of valence electrons. Valence electrons are the electrons in the outermost shell of an atom.
Identifying the Valence Shell The outermost shell in this electron configuration is the third shell, which corresponds to n = 3 . The subshells in the third shell that contain electrons are 3 s and 3 p .
Counting Valence Electrons The number of electrons in the 3 s subshell is 2, and the number of electrons in the 3 p subshell is 4. To find the total number of valence electrons, we add the number of electrons in these subshells: 2 + 4 = 6 .
Final Answer Therefore, the number of valence electrons in the element with the given electron configuration is 6.
Examples
Understanding valence electrons is crucial in chemistry as they determine how an element will interact with other elements to form chemical bonds. For instance, elements with similar numbers of valence electrons often exhibit similar chemical properties. Knowing the number of valence electrons helps predict the types of bonds an element is likely to form, such as covalent or ionic bonds, which is fundamental in designing new materials or understanding chemical reactions.
