1. Atoms, formulas and equations

2. Learning Objectives Know the properties of mixtures and compounds Explain how atomic structure relates to the Periodic Table Show how atomic structure enables chemical bonding and rearrangement of atoms to form new substances

3. Mixtures

4. Easily separated No chemical bonds Can be separated physically e.g. heating, as in distillation Examples of mixtures are: a)Iron filings powder and sulfur powder b)crude oil

5. Compounds Atoms join together to form compounds, by giving, taking or sharing electrons This holds the compound together with chemical bonds Bonding is a chemical reaction. No atoms are created or destroyed, only rearranged

6. Chemical Reactions Only electrons in the outer shell of the atom are involved Opposites attract : +ve and –ve Chemical reactions depend on this Some reactants need heat for a reaction to take place Atoms are the same at the end of the chemical reaction, but in a different arrangement

7. Reactants and Products Some energy is “lost” in every chemical reaction, because of the movement of the atoms during the chemical process Yield is never 100%

8. Molecular Weight Atoms have a Mass Number The relative mass of an element is known as the MOLE of that substance The mole is given in grams. 1 mole = relative atomic mass of any substance expressed in grams

9. The Periodic Table All substances consist of atoms. An element is a substance made from one type of atom only There are about 100 elements in the Periodic table arranged to show: Groups (vertical) elements with the same properties Periods (horizontal)arranged in order of atomic number

11. Key Words Electrons compounds bonds mixtures equation ionic covalent mole formulas

12. An equation is…

13. A chemical reaction

15. Balancing Equations The number of atoms on the left should equal the number of atoms on the other side Bonds are broken and reformed

17. Bleach is added to swimming pools to kill harmful bacteria. Getting the quantities right is checked every day. When chlorine gas is pumped through a solution of sodium hydroxide dissolved in water: Sodium hydroxide + chlorine –> bleach + salt + water