Display

• A laptop's LCD, or liquid crystal display, uses rare earth elements such as europium and terbium in compounds called phosphors. The phosphors glow in the primary colors, red, blue and green. As the liquid crystal display makes no light of its own, but acts as a colored filter, it has a light source behind it called a backlight. Early laptops had fluorescent lamps that used small amounts of mercury. While bright and inexpensive, they posed a hazard, especially for those dismantling old equipment. Light-emitting diodes, or LEDs, now replace fluorescent lamps in these displays. The LEDs use tiny amounts of the elements gallium and arsenic. The arsenic is present in trace quantities and sealed in hard plastic.
  
  

Electronics

• Electronic components consist of a variety of materials, including metal, ceramic and plastic. The most expensive parts, such as the microprocessor and memory, are made of the elements silicon, oxygen and traces of arsenic, boron and phosphorous. The trace materials cause the silicon to favor positive or negative electric charges, depending on the element. These semiconductor materials also use metals. Lithium is another element worth mentioning; rechargeable batteries use it, making laptops lighter than they otherwise would be.
  
  

Body

• The bodies of laptop computers are combinations of plastic and metal. The metal contains iron, in the form of steel, and aluminum. Plastics are hydrocarbon materials made chiefly of hydrogen and carbon, with silicon, phosphorus, sulfur and other elements contributing to the materials.
  
  

Other Components

• The tiny motor that powers the laptop's hard drive has magnets made of a neodymium-iron-boron alloy, or metal mixture. Neodymium exhibits the greatest magnetic strength ever measured for permanent magnets; motors made with the element are very powerful for their size. Like other electronic devices, laptops have hundreds of soldered connections that join electrical and electronic components. With electronics manufacturers increasingly reducing their use of hazardous materials, they have largely discontinued the use of lead-based electronics solder. New solders use metals such as bismuth, silver, copper and tin.