CHAPTER 4 QUEST - Hudson City School District



name chapter 4 review worksheet

calculate the average atomic mass for each element below. then identify the element’s atomic number, # of protons,

# of electrons and # of neutrons. in order to receive credit, all calculations must be shown. don’t forget to maintain sigfigs in your calculations. circle or highlight all answers.

|ISOTOPE |MASS (AMU) |% ABUNDANCE |

|84Sr |83.913425 |0.56 0.46942 |

|86Sr |85.9092624 |9.86 8.47065 |

|87Sr |86.9088793 |7.00 6.08362 |

|88Sr |87.9056143 |82.58 72.59246 |

87.6166

Average Atomic Mass 87.62

Atomic Number 38

# Protons 38

# Electrons 38

# Neutrons 50

|ISOTOPE |MASS (AMU) |% ABUNDANCE |

|74Se |73.9224766 |0.89 0.65791 |

|76Se |75.9192141 |9.37 7.11363 |

|77Se |76.9199146 |7.63 5.86894 |

|78Se |77.9173095 |23.77 18.52094 |

|80Se |79.9165218 |49.61 39.67635 |

|82Se |81.9167000 |8.73 7.15733 |

78.989

Average Atomic Mass 78.99

Atomic Number 34

# Protons 34

# Electrons 34

# Neutrons 45

Numeric Response: answer

3. How many protons are present in an atom of beryllium-10? 4

4. Determine the number of electrons in an atom of iridium? 77

5. What is the mass number for an oxygen atom that has 10 neutrons in its nucleus? 18

6. How many neutrons are in an atom of 235U? 143

7. What is the total number of subatomic particles in the nucleus of an atom of lead-209? 209

8. How many elements are presently recognized as of today? 118

9. Complete the following table.

| | | | | | | |Metal |

|Element Name |Symbol |Mass Number|Atomic Number|# of Protons |# of Electrons |# of Neutrons |Nonmetal |

| | | | | | | |Metalloid |

|Nobelium |No |259 |102 |102 |102 |159 |Metal |

|Rutherfordium |Rf |267 |104 |104 |104 |163 |Metal |

|Yttrium |Y |89 |39 |39 |39 |50 |Metal |

____ 10. The smallest particle of an element that retains the properties of that element is a(n) ____.

|a. |atom |c. |proton |

|b. |electron |d. |neutron |

11. Which of the following is true about subatomic particles?

|a. |Electrons are negatively charged and are the heaviest subatomic particle. |

|b. |Protons are positively charged and the lightest subatomic particle. |

|c. |Neutrons have no charge and are the lightest subatomic particle. |

|d. |The mass of a neutron nearly equals the mass of a proton. |

12. All atoms are ____.

|a. |positively charged, with the number of protons exceeding the number of electrons |

|b. |negatively charged, with the number of electrons exceeding the number of protons |

|c. |neutral, with the number of protons equaling the number of electrons |

|d. |neutral, with the number of protons equaling the number of electrons, which is equal to the number of neutrons |

13. The nucleus of an atom is ____.

|a. |the central core and is composed of protons and neutrons |

|b. |positively charged and has more protons than neutrons |

|c. |negatively charged and has a high density |

|d. |negatively charged and has a low density |

14. The atomic number of an element is the total number of which particles in the nucleus?

|a. |neutrons |c. |electrons |

|b. |protons |d. |protons and electrons |

15. The sum of the protons and neutrons in an atom equals the ____.

|a. |atomic number |c. |atomic mass |

|b. |nucleus number |d. |mass number |

16. All atoms of the same element have the same ____.

|a. |number of neutrons |c. |mass numbers |

|b. |number of protons |d. |mass |

17. Isotopes of the same element have different ____.

|a. |numbers of neutrons |c. |numbers of electrons |

|b. |numbers of protons |d. |atomic numbers |

18. Which of the following statements is NOT true?

|a. |Atoms of the same element can have different masses. |

|b. |Atoms of isotopes of an element have different numbers of protons. |

|c. |The nucleus of an atom has a positive charge. |

|d. |Atoms are mostly empty space. |

19. How is the number of neutrons in the nucleus of an atom calculated?

|a. |Add the number of electrons and protons together. |

|b. |Subtract the number of electrons from the number of protons. |

|c. |Subtract the number of protons from the mass number. |

|d. |Add the mass number to the number of electrons. |

20. How do the isotopes hydrogen-1 and hydrogen-2 differ?

|a. |Hydrogen-2 has one more electron than hydrogen-1. |

|b. |Hydrogen-2 has one neutron; hydrogen-1 has none. |

|c. |Hydrogen-2 has two protons; hydrogen-1 has one. |

|d. |Hydrogen-2 has one proton; hydrogen-1 has none. |

21. What unit is used to measure weighted average atomic mass?

|a. |amu |c. |angstrom |

|b. |gram |d. |nanogram |

22. Which of the following equals one atomic mass unit?

|a. |the mass of one electron |

|b. |the mass of one helium-4 atom |

|c. |the mass of one carbon-12 atom |

|d. |one-twelfth the mass of one carbon-12 atom |

23. Which of the following statements is NOT true?

|a. |Protons have a positive charge. |

|b. |Electrons are negatively charged and have a mass of 1 amu. |

|c. |The nucleus of an atom is positively charged. |

|d. |Neutrons are located in the nucleus of an atom. |

24. The atomic mass of an element is the ____.

|a. |total number of subatomic particles in its nucleus |

|b. |weighted average of the masses of the isotopes of the element |

|c. |total mass of the isotopes of the element |

|d. |average of the mass number and the atomic number for the element |

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