Barium is a chemical element that has the symbol Ba and atomic number 56. It belongs to the group of alkaline-earth metals in the periodic table, which is located in the second column of the table. Like other elements in this group, barium is a silvery, soft, and reactive metal with low melting and boiling points. However, its most remarkable feature is its ability to emit green-colored flames when heated, which makes it useful in fireworks and other pyrotechnic displays.
Barium has a total of 56 electrons, which are arranged in four different energy levels or shells around the nucleus. The first shell, which is closest to the nucleus, can accommodate a maximum of two electrons, while the second, third, and fourth shells can hold up to eight, eighteen, and thirty-two electrons, respectively. Based on this configuration, we can determine the number of valence electrons that barium has, which are the outermost electrons that participate in chemical reactions.
Valence electrons are important because they determine the bonding and reactivity of atoms with other atoms to form compounds. The more valence electrons an atom has, the more likely it is to react with other atoms to achieve a stable electronic configuration. This is because atoms tend to gain, lose, or share electrons to fill their outer shells with eight electrons, which is known as the octet rule.
In the case of barium, the valence electrons are located in the fourth shell, specifically in the s-orbital. Since the fourth shell can hold up to 32 electrons, we can calculate the number of valence electrons by subtracting the total number of electrons in the previous three shells from the total number of electrons in the atom. Therefore, the number of valence electrons in barium is two, which corresponds to the two electrons in the s-orbital of the fourth shell.
The fact that barium has only two valence electrons makes it a very reactive element. It can easily form compounds with other elements, particularly those that have more than two valence electrons and can donate them to barium. For example, barium can react with chlorine to form barium chloride (BaCl2), in which barium gains two electrons from two chlorine atoms to fill its outer shell. Barium can also react with oxygen to form barium oxide (BaO), in which barium shares its two electrons with two oxygen atoms to form a stable bond.
In addition to its reactivity, barium is also known for its toxicity. Barium compounds are highly poisonous and can cause serious health problems if ingested or inhaled. This is because barium can interfere with the normal functioning of cells and organs in the body, especially the heart and the nervous system. Therefore, handling barium and its compounds requires special precautions and protective equipment to minimize the risks of exposure.
In conclusion, barium has two valence electrons, which are located in the fourth shell of the atom. These electrons determine the chemical properties and reactivity of barium with other elements. Despite its low number of valence electrons, barium is a highly reactive and toxic element that requires careful handling and disposal in industrial and laboratory settings. Understanding the electronic structure and behavior of barium is essential for its safe and effective use in various fields, including medicine, industry, and entertainment.