1. Elements

2. What is an element? Element: Is a pure substance that cannot be broken down into other substances by chemical or physical means. Gold( Au) Silver(AG)

3. Elements are the simplest of substances

4. It is made up of only one kind of atom. (EG) Aluminum, Zinc & Copper (Pennies) Nitrogen, Oxygen, & Hydrogen

5. Can be identified by its chemical and physical properties

6. Particles of Elements-Atoms Atom: Is the basic particle from which all elements are made.

7. Made up of protons, neutrons, and electrons

8. Different elements have different atoms, henceforth, different properties Lead(Pb) Oxygen(O)

9. (EG) Carbon: A carbon atom has a positively charged center, or nucleus, that contains smaller particles; a cloud of negative charge surrounds it. Fig 5 p. 39

10. When atoms Combine Chemical bonds: When atoms combine Water

11. Molecules: Groups of two or more atoms held together by chemical bonds

12. (EG) Water: A molecule of water consists of an oxyge atom chemically bonded to two hydrogen atoms.

13. Two atoms of the same element can also combine to form a molecule (EG) Oxygen molecules consist of two oxygen atoms O₂ O₃

14. Ionic Bond forms by attraction of opposite charges of valance electrons NaCl: salt

15. Covalent Bond forms by sharing of valance electrons N₂

16. More examples

17. Compounds Compound: Is a pure substance made of two or more elements chemically combined in a set ratio

18. Chemical formula: shows the elements in the compound and the ratio of atoms

19. When elements are chemically combined, they form compounds having properties that are different from those of the uncombined elements

20. Carbon Dioxide: Its chemical formula is CO 2. The number 2 below the oxygen tells you the ratio of carbon to oxygen, 2 to 1 (If there is no number after the symbol, the number 1 is understood).

21. Different ratios mean different compounds (EG) CO