Valence Electrons of Elements (Simplified): Videos & Practice Problems

In the study of main group elements, it is essential to understand the relationship between an element's group number and its valence electrons. The number of valence electrons corresponds directly to the group number of the element. For instance, aluminum, which is located in group 3A, possesses 3 valence electrons. These valence electrons are crucial as they are the outer shell electrons that participate in the formation of chemical bonds.

In addition to valence electrons, the remaining electrons in an atom are classified as inner core electrons. The total number of electrons in a neutral atom is equal to its atomic number, which can be expressed with the equation:

\[ \text{Total Electrons} = \text{Valence Electrons} + \text{Inner Core Electrons} \]

Taking chlorine as an example, it has an atomic number of 17, indicating that it has 17 protons and, importantly, 17 electrons when neutral. Chlorine is found in group 7A, which means it has 7 valence electrons. In the representation of the chlorine atom, the third shell (n = 3) contains these 7 valence electrons. The remaining 10 electrons are distributed in the first and second shells, serving as inner core electrons. Thus, for chlorine, the configuration reveals 7 valence electrons in the outer shell, while the inner core consists of the other 10 electrons.

To determine the number of inner core and valence electrons in a silicon atom, we start by recognizing that silicon is a neutral element with an atomic number of 14, as indicated on the periodic table. The atomic number corresponds to the total number of electrons in the atom. For main group elements, the number of valence electrons can be identified by the group number on the periodic table. Silicon is located in group 4A, which means it has 4 valence electrons.

To find the number of inner core electrons, we subtract the number of valence electrons from the total number of electrons. In this case, we take the total of 14 electrons and subtract the 4 valence electrons:

Inner Core Electrons = Total Electrons - Valence Electrons

Inner Core Electrons = 14 - 4 = 10

Thus, a silicon atom possesses 4 valence electrons and 10 inner core electrons. This understanding of electron configuration is crucial for predicting the chemical behavior of silicon and its interactions with other elements.