Valence electrons are the electrons located in the outermost shell of an atom, and they are the primary participants in the formation of chemical bonds. These outer-shell electrons determine how an element will interact with other substances, which dictates its chemical behavior and reactivity. The element Barium, symbolized as Ba with an atomic number of 56, is a metal. Understanding its unique electron arrangement provides a clear explanation for its distinct chemical properties.
The Number of Valence Electrons in Barium
Barium possesses two valence electrons. These two electrons occupy the outermost energy level, which is the sixth shell of the atom. This specific count places Barium into a particular family of elements on the periodic table. It is classified as an alkaline earth metal, sharing characteristics with elements like Magnesium and Calcium.
Using the Periodic Table to Determine Valence Electrons
The arrangement of elements in the periodic table provides a simple method for determining the number of valence electrons for main-group elements. The periodic table is organized into vertical columns called groups, and the number of the group corresponds to the number of valence electrons for the elements within it. Barium is located in the second column from the left, meaning it belongs to Group 2. This Group 2 classification immediately indicates that Barium has two valence electrons. This simple counting rule applies directly to all elements in Group 1 and Group 2. For other main-group elements, such as those in Groups 13 through 18, the number of valence electrons can be found by subtracting ten from the group number. For example, an element in Group 15 would have five valence electrons.
How Barium’s Valence Electrons Dictate Its Reactivity
The presence of two valence electrons profoundly influences Barium’s chemical reactivity. Atoms seek stability by achieving a full outer shell, a principle known as the Octet Rule, which requires a total of eight outer electrons. Because Barium has only two electrons in its outermost shell, it is energetically favorable for the atom to lose these two electrons rather than try to gain six more. By readily giving up these two electrons, the Barium atom forms a stable positive ion with a charge of \(Ba^{2+}\). The loss of the valence electrons leaves Barium with the electron configuration of a stable noble gas, which is the driving force behind the reaction. This ease of losing electrons makes Barium a highly reactive metal, meaning it is never found in nature as a pure element, but only in compounds.