The chemical element tin (Sn, atomic number 50) is a soft, silvery-white metal known primarily for its resistance to corrosion. Despite its widespread use in metal coatings and alloys, the question of whether pure tin is attracted to a magnet has a simple and direct answer: it is not. This characteristic places it in a specific category of magnetic materials, distinguishing it from common metals like iron that exhibit a strong magnetic pull.
The Definitive Answer: Pure Tin’s Magnetic Classification
Pure tin is scientifically classified as a diamagnetic material, a designation that explains why it is not attracted to a magnet in any practical sense. Diamagnetism describes a very weak response to a magnetic field, where the material is actually repelled rather than attracted. This repulsion is so slight that it is virtually undetectable under normal conditions.
This behavior is rooted in the atomic structure and electron configuration of the tin atom. Tin’s configuration means that all of its electrons are paired up within their orbitals. Magnetism typically arises from the presence of unpaired electrons, whose spin creates a net magnetic moment. Since tin lacks these unpaired electrons, it cannot form a permanent or induced magnetic field strong enough to be pulled toward a magnet.
When a magnetic field is applied to a diamagnetic material like tin, the electron orbits slightly shift to create a temporary, opposing magnetic field. This induced field is what causes the minute repulsion from the external magnet. A material with diamagnetic properties is considered non-magnetic because the force of repulsion is millions of times weaker than the attraction exhibited by common magnets.
Addressing the Confusion: Why “Tin Cans” Stick to Magnets
The common experience of a magnet sticking to a “tin can” is the primary source of confusion regarding tin’s magnetic properties. The items colloquially known as tin cans are not actually made of pure tin; they are constructed almost entirely from steel, which is an alloy of iron and carbon. Iron is a highly magnetic metal, meaning the can’s attraction to a magnet is due to its steel foundation.
The role of tin in a modern “tin can” is limited to a very thin coating applied to the steel base. This tin plating serves a protective function, preventing the iron in the steel from oxidizing and corroding, which is especially important for preserving food. The magnetic attraction of the massive steel core completely overwhelms the non-magnetic behavior of the microscopic tin layer.
Other common materials containing tin, such as solder and pewter, are also generally non-magnetic unless they incorporate ferromagnetic elements. Solder, typically a tin-lead or tin-silver alloy, and pewter, an alloy of tin, copper, and antimony, remain non-magnetic because their constituent elements lack the atomic structure required for strong magnetism. Any noticeable magnetic behavior in these alloys would suggest the presence of an impurity or a deliberate addition of a magnetic metal.
Comparing Magnetic Behaviors in Common Metals
The way a metal interacts with a magnetic field allows scientists to sort materials into three main categories. The strongest type of magnetism is ferromagnetism, which causes a material to be strongly attracted to a magnet and capable of retaining its own magnetic properties after the external field is removed. Iron, nickel, and cobalt are the most well-known metals that exhibit this intense magnetic response.
The second category is paramagnetism, which describes a weak attraction to a magnet. Paramagnetic materials contain some unpaired electrons that align with an external magnetic field. This alignment is disorganized by thermal energy and disappears immediately when the field is removed. Metals such as aluminum, platinum, and magnesium display this weak, temporary magnetic pull.
Diamagnetism represents the third classification, where the material is weakly repelled by a magnetic field. Pure tin falls into this group alongside other metals like copper and bismuth. The difference between these three classifications lies in the internal structure of the atoms and the arrangement of their electrons, which dictates the strength and direction of the material’s interaction with a magnetic force.