Copper conducts electricity well and is used in electric wires. Copper and gold are the only colored metals. Most colored alloys, such as brass and bronze, contain copper. Zinc and copper make brass. Germanium is used in electronic devices, such as transistors.
Arsenic compounds are poisonous.
Selenium is used in solar cells and light detectors. Krypton is an inert gas used in lasers. Rubidium is used in solar cells and light detectors. Strontium is used in red fireworks. Yttrium is used in red phosphors in televisions.