Valence electron

SUBATOMIC PARTICLES Proton ? 1 positive charge (P+) Neutron ? no charge (N0) Electron ? 1 negative charge (E+) Nucleus An atom's dense central core, containing protons and neutrons. Electrons move around the nucleus Matter Anything that has mass and takes up space Elements Substance that cannot be broken down by a chemical reaction 92 occur naturally 25 of which are essential for life Bulk elements Required by the body in large amounts C N H O (make up 96% of the body) Trace elements Required by the body in small amounts Ultra trace elements Required by the body in minute amounts Atoms Smallest unit of matter that still retains properties of an element Weight Add proton and neutrons together for weight of nucleus Every proton and neutron weights one Dalton