Tungsten (W), element number 74, is a dense, hard metal known for having the highest melting point of all pure elements. This property makes it invaluable in high-temperature applications, such as electrical contacts, specialized alloys, and incandescent light bulb filaments. The atomic number (74) dictates the number of electrons present in a neutral atom. Therefore, a neutral tungsten atom contains precisely 74 electrons, a fixed quantity that dictates the element’s chemical behavior.
The Electron Count in a Neutral Atom
The number of electrons in a neutral tungsten atom is determined by the atomic number (Z), which is 74. This means every tungsten atom contains 74 positively charged protons within its nucleus. The number of protons uniquely defines an element. In a stable, electrically neutral atom, the total positive charge from the nucleus must be exactly canceled out by the total negative charge carried by the surrounding electrons. This balance requires a neutral tungsten atom to possess exactly 74 electrons. If the number of electrons were to change, the atom would no longer be electrically neutral and would instead become an ion.
Distribution Across Electron Shells
While the total count of 74 electrons is fixed in a neutral atom, their spatial organization around the nucleus is highly specific. These electrons occupy distinct energy levels, visualized as electron shells labeled sequentially starting from the innermost shell as K, L, M, N, O, and P. The K shell, being closest to the nucleus, has the lowest energy and accommodates a maximum of two electrons.
Moving outward, the L shell holds eight electrons, and the M shell contains eighteen electrons. The N shell accommodates its full capacity of thirty-two electrons.
The two outermost shells, O and P, define the configuration for tungsten, a heavy transition metal. The O shell contains twelve electrons, and the outermost P shell holds the final two electrons. This specific arrangement of 2-8-18-32-12-2 is crucial for understanding tungsten’s chemical behavior.
The electrons residing in the outermost shells are collectively considered the valence electrons. These electrons are the furthest from the nucleus and are the primary participants in chemical bonding and reactions. The distribution across these six shells dictates how tungsten interacts with other elements.
Tungsten Ions and Variable Counts
The electron count of 74 is only maintained when the tungsten atom remains electrically neutral. However, tungsten frequently participates in chemical bonding by forming charged particles called ions. An ion is created when an atom loses or gains one or more electrons, which upsets the balance between the protons and electrons. Since the number of protons (74) never changes, altering the electron count is the only way to change the overall charge.
Tungsten typically loses electrons to form positively charged cations, exhibiting several common oxidation states, including +2, +3, +4, +5, and +6. For instance, if a neutral tungsten atom loses four electrons, it forms the \(\text{W}^{+4}\) ion, which would then possess 70 electrons (74 minus 4).
The \(\text{W}^{+6}\) ion is common and stable, often seen in compounds like tungsten trioxide (\(\text{WO}_3\)), resulting from the loss of six electrons. This loss leaves the ion with 68 electrons (74 minus 6). The exact electron count of a tungsten ion always depends directly on the magnitude of its positive charge.