7th Grade Study Guide

Test 8

7B: 05/03/09

7A: 06/03/09

Study Guide.

T or F (All the following statements are True)

1. Chemical are uniform substances with predictable properties.

2. Each chemical has certain chemical and physical properties that distinguish it from other chemicals.

3. Chemical changes are not easily reversed.

4. Chemical changes form new substances, but physical changes do not.

5. Properties are characteristics that distinguish one substance from another.

6. All chemicals can be classified as either elements or compounds.

7. Around 100 elements exist naturally on Earth.

8. The periodic table is a chart in which all known elements are organized according to their chemical properties.

9. All matter in the universe is made up of elements, either alone or in different combinations.

10. Atomic number is the number of protons in the nucleus of an atom.

11. The number of electrons around the nucleus must be equal to the number of protons in the nucleus.

12. Atoms consist of a nucleus composed of protons and neutrons.

13. The nucleus is surrounded by a cloud of electrons.

14. A neutron has almost the same mass of a proton, but an electron has much smaller mass.

15. The columns of the periodic table are referred to as groups, and the rows are referred to as periods.

16. There are 18 groups in the periodic table, numbered from left to right.

17. The elements within a group share more properties with each other than they do with any of the other elements. Ex: elements in group 1 are metals, while elements in group 18 are gases.

18. There are 7 periods.

19. The periodic table arranges the elements in order of increasing atomic number in horizontal rows, with elements that look and act alike in vertical columns.

20. The chemical formula of water is H2O.

Answer.

1. Definition of: Reactants, products, word equation.

2. Describe water (at least 5 properties) that does no confuse it with other liquids, such as oil, alcohol, vinegar etc.

3. List: the six elements found in all living things. (with the symbol); The three most abundant elements on the Earth's crust.

4. How many protons are found in then nucleus of Helium, Carbon, Nitrogen, and Oxygen? how many electrons?

5. Write the chemical equation and word equation for the reaction of hydrogen and oxygen to form water, and the reaction of carbon with oxygen to form Carbon dioxide. (S131).