emily6738 emily6738 03-12-2020 Chemistry contestada Find the element: 1. A group 12 metal that was once used in thermometers, but now it’s know to be poisonous. 2. Has 3 valence electrons and 4 energy levels. 4. The only metalloid with 3 valence electrons. 5. It’s most common isotope has 5 neutrons.