Grade 7 Revision sheet Key Answer Question 1: Directions: On each line, write the term that correctly completes each sentence. A. The Parts of an Atom 1. atoms, 2. particles; Number 3. Nucleus a. Proton b. Neutron 4. electron a. electros ; protons b. electron cloud. c. empty; charge. d. nucleus, nucleus. B. The Size of Atoms 1. atoms. 2.orange, earth. C. Differences in Atoms 1. positive, negative, protons. 2. atomic number a. atom. b. protons. 3. isotope. 4. protons, electrons.
a. electrons, negative; electrons, positive b. ion c.protons. D. Atoms and Matter 1. protons 2. protons, neutrons. 3. combine, particles. E. solid. F. mass, space G. solubility. H. liquid. I. chemical. J. boiling K. magnitism Question2: What effect does changing the number of particles in an atom has on the atom s identity? Directions: Complete the chart with the correct terms or numbers: 1. new element refer to the periodic table, it is Nitrogen 2. 7 protons 3. 7neutrons 4. 7 electrons
5. Isotope 6. 6 protons 7. 7neutrons 8. 7electrons 9. negative ion 10. 6 protons 11. 6 neutrons 12. 7 electrons 13. Positive Ion 14. 6 protons 15. 6 neutrons 16. 5 electrons Question 3: Directions: Respond to each statement on the lines provided.. a. The atomic number is the number of protons, in a neutral atom the number of protons and electrons are equal, that s why the number of electrons in sodium atom is 11 b. The green wall absorbs all colors except green. The green wavelengths reflect to your eye, so you see green. The color of an opaque object is the color it reflects c. The red plastic wrap absorbs all colors except red. The red wavelengths reflect to your eye, so you see red. The color of an opaque object is the color it reflects. d. 1- Mass 2-Weight 3-Volume 4-Melting & boiling point 5-Magnetism e. 1- Flammability 2- Reactivity f. 1- Formation of gas 2- Formation of a Precipitate 3- Color change
Question4: Directions: solve the following problems: a- Density = Mass 25, D= Volume 50 b- Density = Mass, Volume = Volume c-, D= 0.5 g/ cm3 Mass Density 25, V =, V = 5 cm3 5 Volume = Length X Wedth X Height V = 8 cm X 4 cm X 5 cm V = 160 cm 3 Volume = Length X Wedth X Height V = 4 cm X 3 cm X 2 cm V = 24 cm 3 d- red ball 2 cubic centimeters, 8 grams yellow ball 80 cm 3, 40 g, green ball 30 cm 3, 120 g white ball 10 cm 3, 10 g, black ball 10 cm 3, 160 g Density = Mass Volume D, Red= 4 g/ cm 3 D, Yellow = 0.5 g/ cm 3 D, Green = 4 g/ cm 3 D, White = 1 g/ cm 3 D, Black = 16 g/ cm 3 1. Volume: Red White, Black Green - Yellow 2. Mass: Red- White Yellow Green - Black 3. Density: Yellow White Red, Green Black Question 5: Compare between the following scientific terms: Homogeneous mixtures The substances are evenly mixed Heterogeneous mixtures The substances are non- evenly mixed Physical change The identity of a substance does not change Chemical change substances react with one another to make new substance
Mass The amount of matter in an object Weight The gravity force that pull the objects down Melting point The temperature at which a solid substance turns to liquid boiling point The temperature at which a liquid substance turns to gas Question 6: Directions: Define each term below. Then answer each question or respond to each statement on the lines provided. Use complete sentences. a- Is a force that resists the sliding of two surfaces that are touching/ or the force that prevent the easy movement between objects b- The energy is not created nor destroyed, it transformed from one form to another c- The characteristics that can be observed of measured without changing the identity of the substance Question 7: Directions: On each line, write the term from the word bank that correctly completes each energy transformation Some terms may be used more than once. a- Electricity changes to thermal. b- Electricity changes to sound and radiant. c- Chemical changes to Mechanical. d- Radiant changes to chemical. e- (Heating) coal**: Chemical changes to thermal. f. Nuclear changes to thermal and radiant.
Question 8: How does light differ from other forms of electromagnetic waves? Directions: Complete the chart by writing two characteristics of each electromagnetic wave. Characteristics 1. have the least amount of energy 2. Used in Radios, Televisions, and computer networks 3. Wavelengths of microwaves range from about 1 mm to 30 cm 4. Transmit information by satellites, such as weather radar systems 5. Its wavelength shorter than a microwave but longer than light 6. All warm bodes emit infrared waves 7. A type of electromagnetic wave that the eyes detect. 8. It includes a range of wavelengths 9. It has high energy so it can be harmful to living things 10. The ozone layer in Earth s atmosphere blocks the Sun s most harmful UV ray 11. These waves are very powerful 12. Useful for taking pictures of the inside of the body 13. Vibrations within the nucleus of an atom produce gamma rays. 14. The most powerful rays, Can penetrate very heavy metals,