Valence electrons are those involved in chemical bonding and determine an element’s chemical behavior. Polonium (Po), an element with atomic number 84, has exactly six valence electrons. A neutral Polonium atom has exactly six valence electrons. This number places Polonium within a particular family on the periodic table and dictates its interactions with other elements.
Locating Polonium and its Electron Count
The easiest method for finding an element’s valence electron count involves its position on the periodic table. Polonium is located in Group 16, a column often referred to as the Oxygen Group or the Chalcogens. For the main group elements (Groups 1, 2, and 13-18), the number of valence electrons corresponds directly to the group number (ignoring the tens digit for Groups 13 through 18).
This means that all elements in Group 16, including Oxygen, Sulfur, Selenium, Tellurium, and Polonium, share the characteristic of having six outer electrons. Polonium is situated in the sixth period, which indicates its outermost electrons occupy the sixth electron shell. This simple periodic table shortcut immediately identifies the count of electrons available for bonding.
Polonium’s Full Electron Structure
The technical explanation for Polonium’s six valence electrons is found in its complete electron configuration, which describes the arrangement of all 84 electrons. An element’s valence electrons are defined as the electrons that reside in the highest principal quantum number shell, which is the sixth shell for Polonium.
Polonium’s abbreviated electron configuration is written as \([\text{Xe}] 4f^{14} 5d^{10} 6s^2 6p^4\). The notation \([\text{Xe}]\) represents the filled electron shells of the preceding noble gas, Xenon. The \(4f^{14}\) and \(5d^{10}\) subshells contain inner electrons that are considered part of the core and do not participate in valence bonding.
The valence shell is the sixth principal energy level (\(n=6\)), which contains the \(6s\) and \(6p\) subshells. Within this shell, there are two electrons in the \(6s\) subshell and four electrons in the \(6p\) subshell, totaling \(2 + 4 = 6\) valence electrons. This specific \(s^2p^4\) arrangement is characteristic of every element in Group 16.
How Six Valence Electrons Influence Reactivity
The six valence electrons govern Polonium’s propensity to form chemical bonds. Atoms generally follow the Octet Rule, striving to acquire eight valence electrons to mimic the stability of a noble gas. Since Polonium has six, it must gain or share two additional electrons to complete its octet.
This drive for two extra electrons dictates Polonium’s common oxidation states in compounds. Polonium typically exhibits oxidation states such as \(-2\), \(+2\), \(+4\), and \(+6\). The \(-2\) state occurs when the atom gains two electrons, while the \(+4\) and \(+6\) states involve sharing or losing all or some of the valence electrons in chemical bonds. The \(+4\) state, which uses the four \(p\) electrons for bonding, is the most stable form in many solutions.
The six valence electrons also mean Polonium is chemically similar to its lighter congeners, Sulfur and Tellurium, often forming analogous compounds. Due to its large atomic size and the complex arrangement of its inner electrons, Polonium exhibits more metallic character than the non-metallic Oxygen and Sulfur. This metallic tendency means Polonium is more likely to lose electrons than its lighter group members, particularly in its higher oxidation states.