1. Structure of Matter Unit Vocabulary

2. Atomic number The number of protons in an atom’s nucleus

3. Chemical symbol A shorthand way to write the name of an element. Example: Ag = Gold

4. Electron Negatively charged particles that move around the nucleus of an atom.

5. Isotope Atoms of the same element that have different numbers of neutrons Example: Boron – 10 and Boron - 11

6. Neutron Atomic particle with no charge, neutral, that is part of an atoms nucleus

7. Mass number Sum of the numbers of the protons and neutrons in an atom’s nucleus

8. Periodic table A chart of elements arranged according to repeated changes in properties

9. Proton Atomic particle with a positive charge that is part of an atom’s nucleus

10. Quark 6 small particles that make up a neutron and proton

11. Boiling point The temperature at which vapor bubbles from in a liquid form to rise to the surface, increasing evaporation

12. Density Describes how tightly packed a substance’s molecules are

13. Density formula The mass per unit volume of a material D=M/V D=density M=mass V=volume

14. Ion A positively or negatively charged atom

15. Nonpolar molecule A molecule that does not have oppositely charged ends

16. Toxic Hazardous substance that can injure living tissues

17. Chemical formula A precise statement that tells which elements are in a compound and their ratios

18. Chemically stable Describes an atom whose outer energy level is completely filled with electrons

19. Corrosive Hazardous compound that attacks and alters metals, human tissue or other materials

20. Covalent bond A type of chemical bond formed by atoms when they share electrons, producing molecules

21. Chemical bond The force that holds together the atoms in a compound, occurs because atoms of most elements become more stable by gaining, losing and sharing electrons