Periodic Table of Elements

4. A horizontal row on the periodic table; elements in the same period have the same number of electron shells.
5. The number of protons in an atom; it defines which element it is.
8. Negatively charged particles that move around the outside of the nucleus in electron shells.
9. Neutral particles (no charge) found in the nucleus of an atom.
10. The electrons in the outermost shell of an atom that are involved in chemical bonding.
12. The energy levels around the nucleus where electrons are found.
13. Elements that are dull, brittle, poor conductors, and often gases or powders at room temperature.
15. A chart that organizes all known elements by their properties and atomic number.

1. Positively charged particles found in the nucleus of an atom.
2. Elements that are shiny, good at conducting heat and electricity, and are often malleable (bendable).
3. The central part of an atom where protons and neutrons are located. It contains most of the atom’s mass.
6. Elements that have properties of both metals and nonmetals; they’re semiconductors.
7. How easily an element reacts with other elements; highly reactive elements form compounds quickly.
11. The total mass of an atom, equal to the number of protons plus neutrons.
14. A vertical column on the periodic table; elements in the same group have similar properties.