Elements and Compounds

elements and Compounds for Grade 7

1. Elements and Compounds Science 7

2. A form of matter which cannot be separated by physical means . A sample of matter that has definite chemical and physical properties. PURE SUBSTANCE It is further classified into two: ELEMENTS and COMPOUNDS

3. Atoms – the basic particle from which all ELEMENTS are made.

4. Molecules – groups of two or more atoms held together by chemical bond. ELEMENTS VS. COMPOUNDS Elements Compounds Contains only one kind of atom. Contains two or more kind of atoms Pure substance that cannot be separated into simpler substance by physical or chemical means. Can only be separated by chemical means.

5. ELEMENTS a pure substance with one kind of atom (same number of protons and electrons).

6. COMPOUNDS It has definite composition. You cannot vary the amount of each element in a compound. Elements are chemically joined together, and can only be separated using chemical reactions. The compound has properties different form the elements it contains.

7. Table Sugar Commonly used in food technology Element or Compound?

8. Element or Compound? Copper Commonly used in electrical equipment such as wiring and motors.

9. Diamond Commonly used in jewelry Also used in cutting, grinding and drilling materials. Element or Compound?

10. Element or Compound? Table Salt Commonly used in cooking, production of soap and food preservation.

11. Tin can A single-use container for packaging Element or Compound?

12. Element or Compound? Neon Lights Mainly used to make dramatic , multicolored glowing signage for signage for advertising.

13. Element or Compound? Sea Shells Used to create mosaics , decorate walls and furnitures .

14. Element or Compound? Baking Soda Used in cooking and baking. Also used as mouthwash and deodorant.

15. Element or Compound? Silver Candle Holder Serves as a stand for candles.

16. Element or Compound? Gasoline Mainly used as a transportation fuel, and also used to fuel electricity generators.

17. Summary of Examples Element Compound 1. Copper (Cu) 1. Table Sugar (Sucrose - C 12 H 22 O 11 ) 2. Diamond (C) 2. Table Salt (Sodium Chloride - NaCl) 3. Aluminum Can (Al) 3. Baking Soda (Sodium Bicarbonate - NaHCO 3 ) 4. Neon Gas (Ne) 4. Gasoline (Octane - C 8 H 18 ) 5. Silver Candle Holder (Ag) 5. Sea Shells (Calcium Carbonate - CaCO 3 )

18. A _________ is formed when two or more elements chemically combined. A scientist discovered a new substance composed entirely of Silicon (Si) atoms, therefore it is a/an _________. Sugar is an example of what? Which of the following is a compound? a. Co b. He c. CO d. H 5. How many Oxygen atoms are there in Fe 3 O 4 ?