1. Science 5 Physical Science

2. Standard/s Covered Students will learn… a.what a chemical reaction is. b.how compounds are formed. c.how formulas of compounds provide information on its composition.

3. REVIEW Matter is anything that has mass and occupies space. Air, water, and pencil are all examples of matter. Matter is made up of tiny particles called atoms. These atoms constantly move. Molecules are formed when atoms combine. Some molecules exhibit crystalline shapes: the particles occur in well- ordered patterns.

4. A compound is formed when elements (or atoms) combine through a chemical reaction. The particles making up a compound are called molecules. Caffeine, found in coffee, is a compound made up of Carbon, Hydrogen, Oxygen, and Nitrogen. C 8 H 10 N 4 O 2 is the formula for this compound.

5. These terms may be confusing… Atoms: the basic building block of matter. Elements: There are 105 different elements on Earth, each represented by 117 different kinds of atoms. Atoms combine in specific ratios to form compounds. Each particle representing a compound is called a molecule.

6. Examples… Water is a compound. The formula is H 2 O. Two atoms of Hydrogen combined with one atom of Oxygen to form one molecule of water.

7. Other common compounds: A molecule of Carbon dioxide. The compound’s formula is CO 2. A molecule of ammonia. This compound has the formula NH 3.

8. Molecules are formed through a process called chemical reaction. In a chemical reaction, molecules break up to form entirely new compounds.

9. How is salt (NaCl) formed? 2Na + Cl 2 2NaCl Sodium metal is silver and shiny. Chlorine gas is a greenish gas that is very poisonous. Salt is harmless, white, makes food taste better!

10. In a chemical reaction… The properties of the reactants (substances that entered the reactions) are very different from the properties of the product/s (substances that are produced).

11. No mass is “lost” or “gained” in a chemical reaction. The mass of the reactants equal the mass of the products.