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Physical Science Chapter 4 Study Guide Name: _______________________________ The mass number of an atom is the number of protons and neutrons in the atom. 1. 2. True or false: Electrons can be found between energy levels? False 3. What is an atom’s nucleus made of? Protons neutrons and electrons What kind of charge does it have? neutral 4. When does an electron jump to a new energy level? When the electron gains or loses energy 5. List three key components of Dalton’s atomic theory. All atoms of a given element are exactly alike, atoms of different elements join to form compounds, atoms can be divided 6. If an element has 22 protons, 24 neutrons, and 22 electrons, what is its mass number? 46 (atomic mass= number of protons + number of neutrons) 7. An element with different isotopes has a different neutrons (also, atomic mass) 8. An atom has a charge that is generally neutral (because it has Equal #s of protons and electrons) 9. The atomic number of an atom is the same as the # of protons 10. Rutherford’s model determined that an atom’s positive charge is concentrated in the atom’s center. 11. True or false: Neutrons have a positive charge? False 12. Thomson discovered that an atom contains negatively charged particles (electrons). 13. What did Thomson use to make his discovery about the atom? Cathode ray 14. Thomson determined that atoms could be divided. 15. Why is it that atoms have no electric charge? They are neutral because they have the same # of protons and electrons 16. According to the modern atomic theory, is it possible for us to determine an electron’s exact position? no 17. What does a mole describe? Measures how many particles are in a substance 18. Why was Democritus’s original atomic theory revised? No evidence to convince or support his claims 19. Which subatomic particle carries a negative charge? electrons 20. Why was Dalton’s atomic theory accepted? He had evidence to support claims 21. Describe Rutherford’s atomic model. The mass is in the center of the cell (nucleus) 22. How do isotopes affect an element’s average atomic mass? The number of neutrons are different so it changes the mass 23. Why do atoms have no electric charge in spite of the fact that they are made of charged particles? They are neutral, same # of protons and electrons 24. Describe how ions are formed. When an atom gains or loses one or more electrons the charge changes (more electrons= negative; fewer electrons= positive) 25. Pretend you are looking at a periodic table. How do you find the number of protons, neutrons, and electrons for a given element? Atomic number: number of protons Atomic mass: protons + neutrons Neutral atom: protons=electrons Positive: protons>electrons Negative: protons<electrons