The question of whether a magnet will stick to a piece of tin seems simple, yet it involves a fundamental misunderstanding between the pure element and common household objects. People are often confused when a magnet either strongly attracts or completely ignores an item they call “tin.” To resolve this puzzle, one must look beyond the name and examine the specific atomic structure and composition of the material in question. The answer lies in the differences between elemental tin, the physics of magnetic forces, and the engineering of modern containers.
The Elemental Properties of Tin
Elemental tin (Sn) is a soft, silvery-white metal that is highly resistant to corrosion. If tested, a piece of high-purity tin will not attract a standard refrigerator magnet. This is because pure tin is not a ferromagnetic material, which is the category of metals that exhibits strong attraction to magnets.
The scientific reason for tin’s non-magnetic behavior lies in its electron configuration. Tin’s electrons are almost all paired, preventing the formation of the internal magnetic domains required for strong magnetism. Although scientific measurements classify tin as weakly diamagnetic or paramagnetic, this effect is too slight to be noticeable outside of a laboratory. For practical purposes, pure tin is considered non-magnetic and will not visibly attract or repel a magnet.
Understanding Magnetic Attraction
A material’s ability to interact with a magnet is determined by how its electrons behave when exposed to a magnetic field. This behavior is categorized into three main types, but only one produces the strong “sticking” effect associated with magnetism. The strongest form is ferromagnetism, exhibited by elements like iron, nickel, and cobalt.
Ferromagnetic materials possess unpaired electrons that align their individual magnetic moments in the same direction over large regions, called magnetic domains. When an external magnet is brought near, these domains align, creating a powerful, sustained attraction that causes the magnet to stick. This is the only type of magnetism that results in the strong, persistent bond people typically associate with magnets.
Paramagnetic materials, such as aluminum, exhibit a much weaker form of attraction. These substances have unpaired electrons that align only temporarily in a strong magnetic field, but the attraction is too weak to overcome gravity. Diamagnetic materials, including copper and water, have all paired electrons and generate a weak, opposing magnetic field, resulting in slight repulsion. Pure tin’s magnetic behavior falls into one of these two weak categories, which explains why it cannot support the weight of a magnet.
Why Magnets Stick to “Tin Cans”
The confusion arises because common objects referred to as “tin cans” are rarely made of solid tin. The vast majority of modern food and aerosol containers are constructed primarily from steel, an alloy of iron and carbon. Steel is highly ferromagnetic due to its high iron content, and this underlying bulk material causes the magnet to stick.
Historically, the term “tin can” originated because the steel body was plated with a micro-thin layer of tin, creating tinplate. This tin coating, which usually makes up less than two percent of the can’s total weight, serves a specific engineering purpose. Tin resists corrosion and prevents the iron in the steel from reacting with the contents, which would otherwise cause the contents to spoil or the can to rust.
When a magnet attracts a “tin can,” the force passes through the non-magnetic tin coating to engage with the highly ferromagnetic steel body beneath. This structural design combines the strength and low cost of steel with the chemical inertness of tin. If a magnet does not stick to a modern can, the container is likely made from aluminum, which is paramagnetic and will not produce a visible attraction.