DRA D2D 2025 Crash Course (Atomic Structure) PDF

1. Which of the following articles has no charge? o a) Proton o b) Neutron o c) Electron d) Positron 66 o...

1. Which of the following articles has no charge? o a) Proton o b) Neutron o c) Electron d) Positron 66 o 28 2. The atomic number of an element is determined by the number of: 73 o a) Protons 02 o b) Neutrons 62 o c) Electrons e) ur o d) Nucleons ct 3. Which of the following models was proposed by J.J. Thomson? ru St o a) Plum pudding model ic o b) Nuclear model m to o c) Planetary model (A o d) Quantum mechanical model e rs 4. Rutherford's gold foil experiment led to the discovery of: ou o a) Electrons C o b) Nucleus sh o c) Neutrons ra C o d) Protons 25 5. The mass number of an atom is the sum of: 20 o a) Protons and electrons 2D o b) Protons and neutrons D A o c) Neutrons and electrons R D  o d) Only protons 6. In Bohr's model of the atom, electrons move in: o a) Random paths o b) Elliptical orbits c) Circular orbits 66 o 28 o d) Straight lines 73 7. The quantum mechanical model of the atom was developed by: 02 o a) Niels Bohr 62 o b) Ernest Rutherford e) ur o c) Erwin Schrödinger ct o d) J.J. Thomson ru St 8. The isotope of hydrogen that has one neutron is called: ic o ) Protium m to o b) Deuterium (A o c) Tritium e rs o d) Hydrogen-1 ou 9. Which of the following particles is found in the nucleus of an atom? C o a) Electron sh b) Proton ra o C o c) Positron 25 o d) Neutrino 20 10. The Heisenberg Uncertainty Principle is related to the: 2D o a) Position and momentum of a particle D A R D  o b) Energy and time of a particle o c) Mass and volume of a particle o d) Charge and spin of a particle 11. Which of the following represents the principal quantum number? a) l 66 o 28 o b) m 73 o c) n 02 o d) s 62 12. The shape of an s-orbital is: e) ur o a) Spherical ct o b) Dumbbell ru St o c) Double dumbbell ic o d) Complex m to 13. The Pauli Exclusion Principle states that: (A o a) No two electrons in the same atom can have the same set of quantum e numbers rs ou o b) Electrons occupy orbitals of lowest energy first C o c) Electrons fill degenerate orbitals singly first sh o d) None of the above ra 14. The maximum number of electrons that can be accommodated in an f-orbital is: C 25 o a) 2 20 o b) 6 2D o c) 10 D o d) 14 A R D  15. Which of the following is a transition element? o a) Sodium o b) Chlorine o c) Iron 66 o ) Helium 28 16. The electron configuration of an atom with atomic number 15 is: 73 o a) 1s² 2s² 2p⁶ 3s² 3p³ 02 62 o b) 1s² 2s² 2p⁶ 3s¹ 3p⁴ e) o c) 1s² 2s² 2p⁶ 3s² 3p² 3d¹ ur o d) 1s² 2s² 2p⁶ 3s² 3p⁵ ct ru 17. Which element has the electronic configuration [Ar] 4s¹? o a) Potassium St ic m o b) Calcium to o c) Scandium (A o d) Titanium e rs 18. The Aufbau principle is used to determine: ou o a) The order of filling of atomic orbitals C sh o b) The total number of neutrons in an atom ra o c) The shape of atomic orbitals C o d) The charge on an ion 25 20 19. The de Broglie wavelength is associated with: 2D o a) Particles and waves D o b) Only particles A R D  o c) Only waves o d) None of the above 20. The spin quantum number can have values of: o a) +1 and -1 b) +1/2 and -1/2 66 o 28 o c) 0 and 1 73 o d) +1 and 0 02 21. In the Rutherford model, the majority of the atom's volume is: 62 o a) Empty space e) ur o b) Filled with protons ct o c) Filled with electrons ru St o d) Filled with neutrons ic 22. Which of the following atoms has the smallest atomic radius? m to o a) Hydrogen (A o b) Helium e rs o c) Lithium ou o d) Beryllium C 23. The number of valence electrons in nitrogen is: sh o a) 3 ra C o b) 5 25 o c) 7 20 o d) 8 2D 24. Ionization energy is the energy required to: D A R D  o a) Add an electron to an atom o b) Remove an electron from an atom o c) Combine two atoms o d) Split an atom 25. Which of the following elements has the highest electronegativity? 66 28 o a) Fluorine 73 o b) Oxygen 02 o c) Chlorine 62 o d) Nitrogen e) ur 26. An alpha particle consists of: ct o a) Two protons and two neutrons ru St o b) Two protons and two electrons ic o c) One proton and two neutrons m to o d) Two electrons and two neutrons (A 27. The electron affinity of an atom is: e rs o a) The energy change when an electron is added to the atom ou o b) The energy required to remove an electron from the atom C o c) The energy change when an electron is removed from the atom sh d) The energy change when two atoms combine ra o C 28. The Bohr model of the atom is based on: 25 o a) Classical mechanics 20 o b) Quantum mechanics 2D o c) Special relativity D A o d) General relativity R D  29. The atomic mass of an element is the weighted average of the masses of its: o a) Protons o b) Neutrons o c) Electrons 66 o d) Isotopes 28 30. The number of neutrons in an isotope with a mass number of 35 and atomic number 73 17 is: 02 o a) 17 62 o b) 18 e) ur o c) 19 ct o d) 20 ru St 31. Which of the following is not a fundamental particle in the atom? ic o a) Proton m to o b) Neutron (A o c) Electron e rs o d) Photon ou 32. An isotope is defined as an atom with the same number of protons but a different C number of: sh o a) Neutrons ra b) Electrons C o 25 o c) Nucleons 20 o d) Quarks 2D 33. The probability distribution of an electron in an atom is described by: D o a) The Schrödinger equation A R D  o b) The Heisenberg Uncertainty Principle o c) The Pauli Exclusion Principle o d) The Bohr model 34. Which of the following quantum numbers describes the shape of an orbital? a) Principal quantum number (n) 66 o 28 o b) Azimuthal quantum number (l) 73 o c) Magnetic quantum number (m) 02 o d) Spin quantum number (s) 62 35. The energy levels of electrons in an atom are quantized, meaning they: e) ur o a) Can have any value ct o b) Are continuous ru St o c) Have discrete values ic o d) Are random m to 36. The electron configuration of a neutral atom of chlorine (atomic number 17) is: (A o a) 1s² 2s² 2p⁶ 3s² 3p⁵ e rs o b) 1s² 2s² 2p⁶ 3s² 3p⁶ ou o c) 1s² 2s² 2p⁶ 3s¹ 3p⁶ C o d) 1s² 2s² 2p⁶ 3s² 3p³ sh 37. Which of the following elements has a valence electron configuration of 4s² 3d⁴? ra C o a) Titanium 25 o b) Chromium 20 o c) Manganese 2D o d) Iron D A R D  38. The principle that describes the emission of electrons from a metal surface when light of a certain frequency is shone on it is called: o a) Photoelectric effect o b) Compton effect o c) Quantum tunneling 66 o d) Blackbody radiation 28 73 39. The sum of the number of protons and neutrons in an atom is called the: 02 o a) Atomic number 62 o b) Mass number e) o c) Isotope number ur ct o d) Nucleon number ru 40. The dual nature of matter is described by: o a) de Broglie hypothesis St ic m o b) Heisenberg Uncertainty Principle to (A o c) Schrödinger equation e o d) Bohr model rs ou 41. The atomic radius of elements generally increases as you move: C o a) From left to right across a period sh o b) From top to bottom in a group ra c) From right to left across a period C o 25 o d) From bottom to top in a group 20 42. The element with atomic number 12 has an electron configuration of: 2D o a) 1s² 2s² 2p⁶ 3s² D o b) 1s² 2s² 2p⁶ 3s¹ 3p¹ A R D  o c) 1s² 2s² 2p⁶ 2d² o d) 1s² 2s² 2p⁶ 3p² 43. Which of the following particles is not a fermion? o a) Proton b) Neutron 66 o 28 o c) Electron 73 o d) Photon 02 44. The nucleus of an atom is held together by: 62 o a) Electromagnetic force e) ur o b) Gravitational force ct o c) Strong nuclear force ru St o d) Weak nuclear force ic 45. The maximum number of electrons that can be accommodated in the second energy m level (n=2) is: to (A o a) 2 e o b) 6 rs ou o c) 8 C o d) 10 sh 46. The quantum number that indicates the orientation of an orbital around the nucleus ra is: C o a) Principal quantum number (n) 25 20 o b) Azimuthal quantum number (l) 2D o c) Magnetic quantum number (m) D o d) Spin quantum number (s) A R D  47. The term "isoelectronic" refers to species having: o a) The same number of protons o b) The same number of neutrons o c) The same number of electrons d) The same number of nucleons 66 o 28 48. Which element has the electronic configuration [Kr] 5s¹ 4d⁵? 73 o a) Yttrium 02 o b) Zirconium 62 o c) Niobium e) ur o d) Molybdenum ct 49. The ionization energy of elements generally decreases as you move: ru St o a) From left to right across a period ic o b) From top to bottom in a group m to o c) From right to left across a period (A o d) From bottom to top in a group e rs 50. The hybridization of carbon in methane (CH₄) is: ou o a) sp C o b) sp² sh o c) sp³ ra C o d) dsp² 25 51. The Heisenberg Uncertainty Principle states that it is impossible to simultaneously 20 know: 2D o a) The exact position and momentum of a particle D o b) The exact energy and time of a particle A R D  o c) The exact charge and spin of a particle o d) The exact mass and volume of a particle 52. The atomic number of an element is equal to the number of: o a) Electrons b) Neutrons 66 o 28 o c) Protons 73 o d) Nucleons 02 53. Which of the following elements is an alkali metal? 62 o a) Magnesium e) ur o b) Potassium ct o c) Aluminum ru St o d) Sulfur ic 54. Which scientist is credited with the discovery of the electron? m to o a) J.J. Thomson (A o b) Ernest Rutherford e rs o c) Niels Bohr ou o d) James Chadwick C 55. The electron configuration of a neutral atom of sodium (atomic number 11) is: sh o a) 1s² 2s² 2p⁶ 3s¹ ra C o b) 1s² 2s² 2p⁶ 3p¹ 25 o c) 1s² 2s² 2p⁶ 3s² 20 o d) 1s² 2s² 2p⁶ 3p² 2D 56. Which of the following orbitals has the highest energy in a multi-electron atom? D A R D  o a) 1s o b) 2s o c) 3p o d) 4d 57. The number of electrons in the outermost shell of an atom determines its: 66 28 o a) Atomic number 73 o b) Isotope 02 o c) Chemical properties 62 o d) Atomic mass e) ur 58. The element with the highest first ionization energy is: ct o a) Helium ru St o b) Fluorine ic o c) Lithium m to o d) Sodium (A 59. The Bohr model of the atom could not explain the spectra of: e rs o a) Hydrogen ou o b) Helium C o c) Lithium sh d) Hydrogen-like ions ra o C 60. The number of protons in an atom is equal to its: 25 o a) Mass number 20 o b) Atomic number 2D o c) Neutron number D A o d) Electron number R D  61. The atomic mass unit (amu) is defined relative to which isotope? o a) Carbon-12 o b) Hydrogen-1 o c) Oxygen-16 66 o d) Nitrogen-14 28 62. In which orbital does an electron experience the least shielding effect? 73 o a) 1s 02 62 o b) 2p e) o c) 3d ur o d) 4f ct ru 63. The magnetic quantum number determines: o a) The shape of the orbital St ic m o b) The orientation of the orbital to o c) The size of the orbital (A o d) The spin of the electron e rs 64. Which of the following elements is a noble gas? ou o a) Neon C sh o b) Nitrogen ra o c) Sodium C o d) Nickel 25 20 65. The maximum number of electrons in the n=3 energy level is: 2D o a) 2 D o b) 8 A R D  o c) 18 o d) 32 66. Which element has the electronic configuration [Ar] 3d¹⁰ 4s² 4p³? o a) Silicon b) Phosphorus 66 o 28 o c) Sulfur 73 o d) Gallium 02 67. Which of the following scientists is credited with the discovery of the neutron? 62 o a) J.J. Thomson e) ur o b) Ernest Rutherford ct o c) James Chadwick ru St o d) Niels Bohr ic 68. The ionization energy of an element generally increases as you move: m to o a) From left to right across a period (A o b) From top to bottom in a group e rs o c) From right to left across a period ou o d) From bottom to top in a group C 69. Which of the following elements has the largest atomic radius? sh o a) Lithium ra C o b) Sodium 25 o c) Potassium 20 o d) Rubidium 2D 70. The second ionization energy is the energy required to remove an electron from a: D A R D  o a) Neutral atom o b) Singly charged cation o c) Doubly charged cation o d) Neutral molecule 71. The ground state electron configuration of an atom indicates: 66 28 o a) The arrangement of electrons in the lowest energy state 73 o b) The arrangement of electrons in an excited state 02 o c) The number of valence electrons 62 o d) The number of unpaired electrons e) ur 72. Which of the following is an alkaline earth metal? ct o a) Sodium ru St o b) Magnesium ic o c) Potassium m to o d) Iron (A 73. The number of unpaired electrons in a carbon atom in its ground state is: e rs o a) 0 ou o b) 1 C o c) 2 sh d) 3 ra o C 74. Which quantum number is associated with the angular momentum of an electron? 25 o a) Principal quantum number (n) 20 o b) Azimuthal quantum number (l) 2D o c) Magnetic quantum number (m) D A o d) Spin quantum number (s) R D  75. The photoelectric effect supports the concept that light has: o a) Particle properties o b) Wave properties o c) Both particle and wave properties 66 o d) Neither particle nor wave properties 28 76. Which of the following elements has the highest electron affinity? 73 o a) Fluorine 02 62 o b) Chlorine e) o c) Bromine ur o d) Iodine ct ru 77. The shape of a p-orbital is: o a) Spherical St ic m o b) Dumbbell to o c) Double dumbbell (A o d) Complex e rs 78. The element with atomic number 19 has an electron configuration of: ou o a) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹ C sh o b) 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹ ra o c) 1s² 2s² 2p⁶ 3s² 3p⁶ C o d) 1s² 2s² 2p⁶ 3s² 3p⁵ 25 20 79. Which of the following statements is true about isotopes? 2D o a) They have the same number of neutrons D o b) They have the same mass number A R D  o c) They have the same atomic number o d) They have different chemical properties 80. The energy difference between two energy levels in an atom is given by: o a) The Rydberg formula b) The Schrödinger equation 66 o 28 o c) The Planck constant 73 o d) The Heisenberg Uncertainty Principle 02 81. Which element has the electronic configuration [Xe] 6s² 4f¹⁴ 5d¹⁰ 6p²? 62 o a) Tin e) ur o b) Lead ct o c) Bismuth ru St o d) Polonium ic 82. The number of protons, neutrons, and electrons in a neutral atom of chlorine-37 is: m to o a) 17 protons, 20 neutrons, 17 electrons (A o b) 17 protons, 17 neutrons, 17 electrons e rs o c) 20 protons, 17 neutrons, 17 electrons ou o d) 17 protons, 20 neutrons, 20 electrons C 83. Which of the following elements has the highest first ionization energy? sh o a) Boron ra C o b) Carbon 25 o c) Nitrogen 20 o d) Oxygen 2D 84. The atomic mass of an element is measured in: D A R D  o a) Atomic mass units (amu) o b) Grams o c) Kilograms o d) Daltons 85. The probability of finding an electron in a particular region of space is described by 66 the: 28 73 o a) Orbital 02 o b) Node 62 o c) Electron cloud e) o d) Probability density function ur ct 86. The Aufbau principle states that electrons fill orbitals: ru o a) From highest to lowest energy o b) From lowest to highest energy St ic m o c) Randomly to (A o d) Based on the Pauli Exclusion Principle e 87. The number of neutrons in an atom of uranium-238 is: rs ou o a) 92 C o b) 146 sh o c) 238 ra d) 330 C o 25 88. The first person to propose the concept of the atom was: 20 o a) Democritus 2D o b) Aristotle D o c) Dalton A R D  o d) Rutherford 89. The electronic configuration of an element with atomic number 24 is: o a) [Ar] 3d⁵ 4s¹ o b) [Ar] 3d⁶ c) [Ar] 3d⁴ 4s² 66 o 28 o d) [Ar] 3d⁵ 73 90. Which of the following principles states that electrons will occupy degenerate 02 orbitals singly before pairing up? 62 o a) Pauli Exclusion Principle e) o b) Aufbau Principle ur ct o c) Hund's Rule ru 91. The maximum number of electrons that can be accommodated in a p-orbital is: o a) 2 St ic m o b) 6 to (A o c) 10 e o d) 14 rs ou 92. The first ionization energy of an element is always: C o a) Positive sh o b) Negative ra c) Zero C o 25 o d) Variable 20 93. Which of the following elements is a lanthanide? 2D o a) Thorium D o b) Uranium A R D  o c) Cerium o d) Actinium 94. The most stable isotope of hydrogen is: o a) Protium b) Deuterium 66 o 28 o c) Tritium 73 o d) Hydrogen-1 02 95. Which of the following orbitals has the lowest energy? 62 o a) 2s e) ur o b) 2p ct o c) 3s ru St o d) 3d ic 96. The principle that states that no two electrons in the same atom can have the same m set of four quantum numbers is known as: to (A o a) Hund's Rule e o b) Aufbau Principle rs ou o c) Pauli Exclusion Principle C o d) Heisenberg Uncertainty Principle sh 97. Which element has the electronic configuration [Ne] 3s² 3p¹? ra a) Magnesium C o 25 o b) Aluminum 20 o c) Silicon 2D o d) Phosphorus D A R D  98. Which of the following statements is true about the periodic table? o a) Elements are arranged in order of increasing atomic mass o b) Elements are arranged in order of increasing atomic number o c) Elements are arranged in order of increasing neutron number d) Elements are arranged in order of increasing electron number 66 o 28 99. The number of valence electrons in an oxygen atom is: 73 o a) 2 02 o b) 4 62 o c) 6 e) ur o d) 8 ct 100. Which scientist is credited with the discovery of the proton? ru St a) J.J. Thomson ic b) Ernest Rutherford m to c) Niels Bohr (A d) James Chadwick e rs 101. The orbital with the highest energy in a given principal energy level is: ou a) s-orbital C b) p-orbital sh c) d-orbital ra C d) f-orbital 25 102. The atomic radius of elements generally decreases as you move: 20 a) From left to right across a period 2D b) From top to bottom in a group D A c) From right to left across a period R D  d) From bottom to top in a group 103. Which of the following elements has the lowest ionization energy? a) Lithium b) Sodium c) Potassium 66 28 d) Cesium 73 104. The number of neutrons in an atom of carbon-14 is: 02 a) 6 62 b) 7 e) ur c) 8 ct d) 14 ru St 105. Which of the following orbitals is degenerate with 3p_y? ic a) 3p_x m to b) 3s (A c) 3d_z^2 e rs d) 4s ou 106. The electron configuration of a neutral atom of sulfur (atomic number 16) is: C a) 1s² 2s² 2p⁶ 3s² 3p⁴ sh b) 1s² 2s² 2p⁶ 3s² 3p³ ra C c) 1s² 2s² 2p⁶ 3s² 3p⁶ 25 d) 1s² 2s² 2p⁶ 3s² 3d⁴ 20 107. Which of the following elements has the highest first ionization energy? 2D a) Lithium D A R D  b) Beryllium c) Boron d) Carbon 108. Which quantum number is associated with the orientation of an orbital in space? 66 a) Principal quantum number (n) 28 73 b) Azimuthal quantum number (l) 02 c) Magnetic quantum number (m) 62 d) Spin quantum number (s) e) 109. The element with atomic number 11 has an electron configuration of: ur ct a) 1s² 2s² 2p⁶ 3s¹ ru b) 1s² 2s² 2p⁶ 3p¹ c) 1s² 2s² 2p⁶ 3s² St ic m d) 1s² 2s² 2p⁶ 3p² to (A 110. The term "nucleon" refers to: e a) Electrons in the nucleus rs ou b) Protons and neutrons in the nucleus C c) Neutrons and electrons in the nucleus sh d) Protons, neutrons, and electrons in the nucleus ra 111. The electron configuration of an element with atomic number 26 is: C 25 a) [Ar] 3d⁶ 4s² 20 b) [Ar] 3d⁵ 4s² 2D c) [Ar] 3d⁴ 4s² D d) [Ar] 3d⁷ 4s² A R D  112. Which of the following statements is true about the d-orbitals? a) They can hold a maximum of 6 electrons b) They can hold a maximum of 10 electrons c) They have a spherical shape 66 d) They have a dumbbell shape 28 113. Which of the following elements is a halogen? 73 a) Oxygen 02 62 b) Fluorine e) c) Neon ur d) Sodium ct ru 114. The Pauli Exclusion Principle is crucial in explaining: a) Electron configuration St ic b) Chemical bonding m to c) Atomic mass (A d) Radioactive decay e rs 115. The number of unpaired electrons in a neutral atom of nitrogen (atomic ou number 7) is: C a) 0 sh b) 1 ra C c) 2 25 d) 3 20 116. Which of the following statements is true about the f-orbitals? 2D a) They are found in the first principal energy level D A R D  b) They can hold a maximum of 14 electrons c) They have a spherical shape d) They are involved in bonding in alkali metals 117. The energy required to remove the first electron from a neutral atom is called: 66 a) Electron affinity 28 73 b) Ionization energy 02 c) Electronegativity 62 d) Binding energy e) 118. The effective nuclear charge experienced by an electron is influenced by: ur ct a) The number of protons in the nucleus ru b) The number of neutrons in the nucleus c) The shielding effect of inner electrons St ic m d) Both a and c to (A 119. The Heisenberg Uncertainty Principle is related to: e a) Position and velocity rs ou b) Position and momentum C c) Momentum and energy sh d) Position and energy ra 120. Which element has the electronic configuration [Rn] 7s² 5f¹⁴ 6d²? C 25 a) Rutherfordium 20 b) Dubnium 2D c) Seaborgium D d) Bohrium A R D  121. The electron configuration of a neutral atom of nickel (atomic number 28) is: a) [Ar] 3d⁸ 4s² b) [Ar] 3d⁹ 4s¹ c) [Ar] 3d¹⁰ 66 d) [Ar] 3d⁸ 28 122. Which of the following elements has the lowest electronegativity? 73 a) Fluorine 02 62 b) Oxygen e) c) Carbon ur d) Cesium ct ru 123. The number of electrons that can occupy a single orbital is: a) 1 St ic b) 2 m to c) 3 (A d) 4 e rs 124. The principle that states that electrons occupy the lowest energy orbital ou available is known as: C a) Hund's Rule sh b) Pauli Exclusion Principle ra C c) Aufbau Principle 25 d) Heisenberg Uncertainty Principle 20 125. Which element has the electronic configuration [Ar] 3d¹⁰ 4s² 4p²? 2D a) Silicon D A R D  b) Phosphorus c) Germanium d) Tin 126. The element with atomic number 12 has an electron configuration of: a) 1s² 2s² 2p⁶ 3s² 66 28 b) 1s² 2s² 2p⁶ 3p¹ 73 c) 1s² 2s² 2p⁶ 3s¹ 3p¹ 02 d) 1s² 2s² 2p⁶ 3p² 62 127. Which of the following elements is an actinide? e) ur a) Cerium ct b) Uranium ru St c) Lanthanum ic d) Thorium m to 128. The effective nuclear charge is: (A a) The net positive charge experienced by an electron in a multi-electron atom e rs b) The total charge of the nucleus ou c) The difference between the number of protons and neutrons C d) The charge of the outermost electron sh 129. The term "valence electrons" refers to: ra C a) Electrons in the innermost shell 25 b) Electrons in the outermost shell 20 c) Electrons in the nucleus 2D d) Electrons in the second shell D A R D  130. Which of the following elements has the electronic configuration [Kr] 4d¹⁰ 5s² 5p⁵? a) Iodine b) Xenon c) Tellurium 66 28 d) Antimony 73 131. The number of neutrons in an isotope of iron-56 is: 02 a) 26 62 b) 28 e) ur c) 30 ct d) 56 ru St 132. Which of the following elements is a metalloid? ic a) Oxygen m to b) Sulfur (A c) Boron e rs d) Phosphorus ou 133. The term "ion" refers to: C a) An atom with a neutral charge sh b) An atom with an equal number of protons and electrons ra C c) An atom with a different number of protons and electrons 25 d) An atom with no electrons 20 134. Which scientist is credited with the development of the quantum mechanical 2D model of the atom? D a) J.J. Thomson A R D  b) Ernest Rutherford c) Niels Bohr d) Erwin Schrödinger 135. The number of valence electrons in a chlorine atom is: a) 3 66 28 b) 5 73 c) 7 02 d) 8 62 136. Which of the following particles is found in the nucleus of an atom? e) ur a) Electron ct b) Proton ru St c) Positron ic d) Neutrino m to 137. The term "isoelectronic" refers to species having: (A a) The same number of protons e rs b) The same number of neutrons ou c) The same number of electrons C d) The same number of nucleons sh 138. Which of the following elements has the highest electronegativity? ra C a) Fluorine 25 b) Oxygen 20 c) Nitrogen 2D d) Sulfur D A R D  139. The number of unpaired electrons in an atom of oxygen (atomic number 8) is: a) 0 b) 1 c) 2 d) 3 66 28 140. The atomic radius of elements generally increases as you move: 73 a) From left to right across a period 02 b) From top to bottom in a group 62 c) From right to left across a period e) ur d) From bottom to top in a group ct 141. The first ionization energy of an element is: ru St a) The energy required to add an electron to an atom ic b) The energy required to remove the most loosely bound electron from a neutral m atom to (A c) The energy change when an electron is added to an atom e d) The energy change when two atoms combine rs 142. Which of the following elements has the electronic configuration [Xe] 6s² 4f¹⁴ ou 5d¹⁰ 6p⁵? C sh a) Bismuth ra b) Polonium C c) Astatine 25 20 d) Radon 2D 143. The quantum mechanical model of the atom describes electrons as: D a) Particles orbiting the nucleus in fixed paths A R D  b) Waves of probability c) Static charges around the nucleus d) Classical particles 144. The number of neutrons in an isotope with a mass number of 56 and atomic number 26 is: 66 a) 26 28 73 b) 30 02 c) 56 62 d) 82 e) 145. Which of the following elements has the electronic configuration [Ar] 4s² 3d⁴? ur ct a) Chromium ru b) Manganese c) Iron St ic m d) Copper to (A 146. The maximum number of electrons that can be accommodated in the third energy level (n=3) is: e rs a) 8 ou b) 18 C sh c) 32 ra d) 24 C 147. Which scientist is credited with the discovery of the neutron? 25 20 a) J.J. Thomson 2D b) Ernest Rutherford D c) James Chadwick A R d) Niels Bohr D  148. The term "orbital" refers to: a) The path of an electron around the nucleus b) A region of space where there is a high probability of finding an electron c) The charge of an electron 66 d) The mass of an electron 28 149. The electron configuration of a neutral atom of argon (atomic number 18) is: 73 a) 1s² 2s² 2p⁶ 3s² 3p⁶ 02 62 b) 1s² 2s² 2p⁶ 3s² 3p⁵ e) c) 1s² 2s² 2p⁶ 3s¹ 3p⁶ ur d) 1s² 2s² 2p⁶ 3s² 3p³ ct ru 150. The effective nuclear charge experienced by an electron in an atom increases St as you move: ic a) From left to right across a period m to b) From top to bottom in a group (A c) From right to left across a period e rs d) From bottom to top in a group ou Answer: a) From left to right across a period C sh ra C 25 20 2D D A R D