ATOMIC BONDING | PRACTICE PROBLEMS Complete the following to reinforce your understanding of the concept covered in this module.
PROBLEM 1: What type of bond exists predominantly in a sodium chloride crystal? A. πππ‘πππππ π΅πππ B. πΌππππ π΅πππ C. πΆππ£πππππ‘ π΅πππ D. πππππ π΅πππ
SOLUTION 1: The TOPIC OF PRIMARY BONDS can be referenced under the topic of ATOMIC BONDING on page 60 of the NCEES Supplied Reference Handbook, Version 9.4 for Computer Based Testing. In a sodium chloride crystal, sodium and chlorine are present as sodium and chloride ions. These ions are arranged in a periodic pattern to form the crystal.
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The electrostatic attraction between the positive sodium ion and the negative chloride ion forms the basis of the ionic bond that exists in a sodium chloride crystal.
Therefore, the correct answer choice is B. π°ππππ π©πππ
PROBLEM 2: Which of the following is the ground-state electron configuration of a copper atom? A. 1π ; 2π ; 2π> 3π ; 3π> 4π A 3πAB B. 1π ; 1π> 2π ; 2π> 3π ; 3π> 3π C C. 1π ; 1π; 2π ; 2π> 3π ; 3π> 4π ; 4π> 4πA D. 1π ; 2π ; 2π> 3π ; 3π> 4π ; 4πD
SOLUTION 2: The TOPIC OF ELECTRON CONFIGURATION OF ELEMENTS is not provided in the NCEES Supplied Reference Handbook, Version 9.4 for Computer Based Testing. We must memorize these concepts and understand their application independent of the NCEES Supplied Reference Handbook. Copper has an atomic number of 29, so we know a copper atom has 29 electrons. In answer choices (B) and (C), the β1πβ levels do not exist. In answer choice (D), the β3πβ level is a higher energy level than the β4π β level.
Therefore, the correct answer choice is B. πππ πππ πππ πππ πππ πππ ππ
ππ
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PROBLEM 3: Which of the following affects most of the electrical and thermal properties of materials? A. πβπ ππ‘ππππ π€πππβπ‘ ππ₯ππππ π ππ ππ πππππ πππ ππππ β ππ‘ππ B. πβπ πππππ‘ππππ , ππππ‘πππ’πππππ¦ π‘βπ π£ππππππ πππππ‘ππππ C. πβπ ππππππ‘π’ππ ππ πππππ‘πππππ πβππππ ππ π‘βπ ππππ‘ππ D. πβπ π€πππβπ‘ ππ π‘βπ ππ‘ππ
SOLUTION 3: The outermost electrons are responsible for determining most of the materialβs properties.
Therefore, the correct answer choice is B. π»ππ πππππππππ, ππππππππππππ πππ πππππππ πππππππππ PROBLEM 4: What are valence electrons? A. πβπ ππ’π‘ππ β π βπππ πππππ‘ππππ B. πΈππππ‘ππππ π€ππ‘β π πππ ππ‘ππ£π πβππππ C. πβπ πππππ‘ππππ ππ πππππππ‘π ππ’πππ‘π’π π βππππ D. πβπ πΎ β ππ’πππ‘π’π π βπππ πππππ‘ππππ
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SOLUTION 4: The valence electrons are the outermost electrons in the electron configuration of an atom.
Therefore, the correct answer choice is A. π»ππ πππππ β πππππ πππππππππ PROBLEM 5: What is the strong bond between hydrogen atoms called? A. πβπ πππππ ππππ B. πβπ πππ‘πππππ ππππ C. πΌππππ πππ πππ‘πππππ πππππ D. πβπ πππ£πππππ‘ ππππ
SOLUTION 5: The TOPIC OF PRIMARY BONDS can be referenced under the topic of ATOMIC BONDING on page 60 of the NCEES Supplied Reference Handbook, Version 9.4 for Computer Based Testing. Covalent bonds provide the strongest attractive forces between atoms.
Therefore, the correct answer choice is π. π»ππ ππππππππ ππππ
π
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PROBLEM 6: Which of the following elements would not be expected to form ionic compounds? A. Silicon B. Potassium C. Barium D. Silver
SOLUTION 6: The PERIODIC TABLE OF ELEMENTS can be referenced under the topic of CHEMISTRY on page 54 of the NCEES Supplied Reference Handbook, Version 9.4 for Computer Based Testing. One way to predict whether a bond is ionic or covalent is to look how far apart the two atoms forming the bonds are in the periodic table. If one atom is of the far left (Group 1 or 2) and the other is on the far right (Group 5, 6, or 7), then the atoms will have large differences in electronegativity and will form an ionic bond. Most other pairs of atoms are close enough in electronegativity to form covalent bonds. For example, any two atoms in the main group elements (Groups 3, 4, 5, 6, 7), will usually form a covalent bond. Silicon does not form ionic compounds. Silicon forms covalent compounds.
Therefore, the correct answer choice is π¨. πΊππππππ
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PROBLEM 7: What is the difference between π ;DC and π ;Dp ? A. πβπ ππ’ππππ ππ ππππ‘πππ B. πβπ ππ’ππππ ππ πππ’π‘ππππ C. πβπ ππ‘ππππ ππ’πππππ D. πβπ ππ’ππππ ππ πππππ‘ππππ
SOLUTION 7: The PERIODIC TABLE OF ELEMENTS can be referenced under the topic of CHEMISTRY on page 54 of the NCEES Supplied Reference Handbook, Version 9.4 for Computer Based Testing. π ;DC and π ;Dp are isotopes and have the same atomic numbers. As they have the same atomic numbers, they have the number of protons and electrons. They differ in the number of neutrons.
Therefore, the correct answer choice is π©. π»ππ ππππππ ππ ππππππππ PROBLEM 8: An isotropic material is one with which of the following properties? A. π·ππππππππ‘ πππππππ‘πππ ππ πππ ππππππ‘ππππ B. ππππ πππππππ‘πππ ππ πππ ππππππ‘ππππ C. π·ππππππππ‘ πππππππ‘πππ ππ‘ πππππππππ‘ πππππ‘ππππ D. ππππ πππππππ‘πππ ππ πππ πππππ‘ππππ
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SOLUTION 7:
An isotropic material is one with the same properties in all directions.
Therefore, the correct answer choice is B. The same properties in all directions.
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