Author Description

Mary and her classmates visit an exhibit at the Lawrence Hall of Science at Berkeley, CA. The museum visit will reinforce the atoms' concepts and how the atoms are joined together to form molecules. An instructor introduces the rocks that are most commonly encountered in the Earth's crust. In rocks, in contrast to metals, the atoms tightly hold their valence electrons, and electrons do not flow through the material even in the presence of a significant voltage difference. This means that rocks do not conduct electricity, and they are called insulators. Stones are mainly made from atoms that do not belong to the Metal groups but belong to the group of Metalloids (semi-metals) and Non-Metals.