Science Gizmo Test Questions with Correct Solutions

Atom - The basic unit of matter. An atom is the smallest particle of the element that still has all the properties of the element. Atoms are made up of smaller particles called protons, neutrons, and electrons. the smaller electrons orbit around a central nucleus of protons and neutrons. Atomic Number - The number of protons in the nucleus of an atom. Elements are distinguished from one another by their atomic numbers. For example, any atom with 2 protons is an atom of helium. The symbol for the atomic number is Z. In an element symbol, the atomic number is shown at lower left. Electron - A negatively charged particle that moves around the nucleus. The mass of an electron is less than one thousandth of the mass of a proton. Electron Dot Diagram - A diagram that shows the element symbol surrounded by dots representing valence electrons. For example, the electron dot diagram at right shows that neutral helium atoms have 2 valence electrons. Element - A pure substance that cannot be broken down into simpler substances by ordinary chemical means. Elements are made up of 1 type of atom. Atoms of different elements are distinguished by the number