A typical cell phone contains some of the most valuable elements on Earth. With everything from gold to silver, it’s like having a little treasure chest in your pocket.
A smartphone is packed with at least 40 elements, says Andy Brunning, a chemistry teacher in Bournemouth, U.K. His website, Compound Interest, illustrates the chemistry of everyday items, like phones. “As far as everyday chemistry goes, the cell phone that most of us carry around is up there,” he says.
Check out the diagram to find out about some of the elements and compounds that put the smarts in your phone.
When you turn on your phone, positively charged lithium ions move through a lithium-salt solution that conducts electricity. Electrons flow out of the battery, producing the electric current that powers your phone. The rechargeable battery’s casing is made of aluminum.
The circuit board has gold, copper, and silver—good electrical conductors. The connectors (pins that join circuits to the circuit board) are coated in gold because it’s highly resistant to corrosion. The wiring is copper. Solder—an alloy of tin, silver, and copper—binds parts of the circuit board.
The chip is the phone’s brain. It has many transistors made of antimony, phosphorus, and gallium arsenide (GaAs). Transistors act as paths and switches that tell the phone to follow or stop following commands. The chip is embedded with silicon—which has low conductivity—to channel electricity only through the conductive transistors.
A thin layer of indium tin oxide—a mixture of indium oxide (In2O3) and tin oxide (SnO2)—conducts electricity. When you touch the screen, a change in the electrical field occurs and communicates your finger’s location to the phone’s chip.
Smartphone screens contain aluminosilicate glass, made from the compounds alumina (Al2O3) and silica (SiO2). If you’ve ever dropped your phone and its screen has stayed intact, you can thank potassium ions (atoms that have gained or lost electrons). They help strengthen the glass.
A cell phone’s display contains several rare earth elements. These elements are spread out widely in Earth’s crust, making them hard to mine. Small quantities of yttrium, europium, and dysprosium help produce the colors on the phone’s liquid crystal display (LCD) screen. Gadolinium, lanthanum, and terbium give the screen its glow.
MICROPHONE AND SPEAKERS
The microphone’s wafer-thin diaphragm, which vibrates when sound waves strike it, is made of nickel. The vibrations are converted into an electrical current that becomes the audio signal.
Magnets vibrate in the speaker to create audible sound. Magnets of neodymium (Nd2Fe14B) are used because they’re the strongest magnets, so even though they’re small, they’re powerful.