Magnesium (Mg) is a silvery-white metal belonging to Group 2 of the periodic table, the alkaline earth metals. It is recognized as the lightest structural metal. Due to its metallic nature, magnesium is an effective conductor of electricity and also exhibits excellent thermal conductivity. This combination of properties, particularly its low mass, makes it a valuable material in various modern technologies.
How Magnesium Conducts Electricity
Magnesium’s ability to conduct an electrical current originates from its atomic structure and metallic bonding. As a metal, magnesium atoms release their outermost electrons into a shared space.
Each neutral magnesium atom possesses two valence electrons. When magnesium solidifies, these electrons become delocalized, moving freely throughout the metallic structure. This process leaves behind a rigid lattice of positively charged magnesium ions (\(Mg^{2+}\)) surrounded by a mobile “sea” of electrons.
These highly mobile, delocalized electrons are the charge carriers responsible for electrical conductivity. When a voltage is applied across the metal, these electrons readily flow toward the positive terminal, creating an electric current. The high concentration of two mobile electrons per atom facilitates this efficient movement of charge.
Ranking Magnesium Against Other Conductors
While magnesium is an excellent conductor, its performance is measured against benchmark materials like copper and aluminum. On a volumetric basis, which measures conductivity per unit volume, pure magnesium has an electrical conductivity of approximately 22 million Siemens per meter (MS/m). This figure places it well below the industry standard.
For comparison, copper measures about 59 MS/m, and aluminum registers around 37 MS/m. This difference means a magnesium wire of the same diameter as a copper wire offers significantly higher resistance to current flow. Consequently, magnesium is not frequently used for long-distance power transmission or high-current wiring where volume is not a significant concern.
The perspective changes when considering conductivity relative to weight, known as specific conductivity. Because magnesium is significantly less dense than both aluminum and copper, its conductivity-to-weight ratio is much more favorable. When weight savings are prioritized, such as in aerospace or portable electronics, magnesium’s low density offsets its lower volumetric conductivity, making it highly competitive.
Applications Leveraging Magnesium’s Electrical Properties
Magnesium’s combination of electrical and thermal conductivity with low density makes it suitable for specific, high-performance applications. One prominent use is in manufacturing casings for portable electronic devices, including laptops, smartphones, and professional cameras. The metal’s electrical conductivity contributes to effective electromagnetic shielding, protecting internal components from external interference.
The metal’s high thermal conductivity, comparable to aluminum, is also utilized in these casings to efficiently dissipate heat generated by internal processors. This dual function of electrical shielding and thermal management is why magnesium alloys are favored for thin, lightweight designs where heat buildup is a concern.
Magnesium also finds its way into specialized alloys used in the automotive and aerospace industries. In these sectors, the goal is weight reduction for improved fuel efficiency or battery range, such as in electric vehicle battery enclosures. Its properties are also leveraged in copper-magnesium alloys for certain types of overhead conductor wires. The added magnesium significantly increases the tensile strength of the wire without severely compromising its conductivity.