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Test bank chapter (9)
Choose the most correct answer
- The two types of chemical bonds commonly found in compounds are:
a) doric and covalent. b) ionic and electrolytic. c) ionic and covalent. d) electrolytic and compound.
- The electrons used by atoms to form chemical bonds are the: a) core electrons. b) valence electrons. c) lone pair electrons. d) unpaired electrons.
- “Atoms tend to gain, lose, or share electrons until they are surrounded by eight valence electrons” is a statement of: a) the rule of octaves. b) the double quartet rule. c) the eight electron rule. d) the octet rule.
- When a transition metal atom becomes a +1 ion, the electron lost usually comes from what type of orbital? a) p b) f c) d d) s
- A molecule of CS 2 contains a) two single bonds. b) two double bonds. c) one single bond and one double bond. d) one single bond and one triple bond.
- An atom in the ground state has atomic number Z=5. Choose the correct electron-dot structure which represents this atom? ANS. B
- Which compound below contains an atom that is surrounded by more than an octet of electrons?
a) PF 5 b) CH 4 c) NBr 3 d) OF 2
- Which choice below correctly lists the elements in order of increasing electronegativity? a) C < N < O < F b) N < C < O < F c) N < C < F < O d) C < N < F < O
- Which atom sometimes violates the octet rule?
a) C b) N c) O d) S
- How many resonance structures can be drawn for NO3–? a) 1 b) 2 c) 3 d) 4
- Considering formal charge, what is the preferred Lewis structure of NCO–? ANS. 1
- In Lewis structure of (SO4)-2structure the correct formal charge on sulfur (S) is: a) + b) - c) + d) 0
- Which of these pairs of elements would be most likely to form an ionic compound?
a) Cl and I b) Al and K c) Cl and Mg d) C and S
- What is the formal charge on the oxygen atom in N 2 O (the atomic order is N-N-O)?
a) 0 b) + c) - d) -
- Which of these substances will display an incomplete octet in its Lewis structure?
a) CO 2 b) Cl 2 c) ICl d) NO
- There are __________ paired and __________ unpaired electrons in the Lewis symbol for a phosphorus atom (P).
a) 4, 2 b) 2, 4 c) 4, 3 d) 2, 3
Explanation: Read the question carefully here, you are being asked for how many valence electrons are paired and how many are unpaired. The abbreviated electron configuration of the P atom is given by [Ne] 3s^2 3p^3. The outermost electrons would be arranged as 2 electrons paired and 3 electrons unpaired as shown below:
- Based on the octet rule, magnesium (Mg) most likely forms a __________ ion.
a) Mg2- b) Mg2+ c) Mg6- d) Mg6+
Explanation: According to the octet rule the Mg atom will achieve an octet by losing its 2 outermost electrons and thus gaining 2+ charges. Since Mg is located in the alkali metal group it will lose electrons rather than gaining them.
- Based on the octet rule, phosphorus (P) most likely forms a __________ ion.
a) P3+ b) P5- c) P5+ d) P3-
Explanation: According to the octet rule the phosphorus atom should gain 3electrons, thus gaining 3 negative charges and forming the phosphide ion.
25- The only noble gas without eight valence electrons is __________.
a) Ar b) Ne c) He d) Kr
Explanation: The noble gases are characterized by the presence of eight electrons in their outermost shell with one notable exception of Helium. Since He has only 2 electrons it can never have 8 in its outermost shell.
26- What is the maximum number of double bonds that a hydrogen atom (H) can form?
a) 0 b) 1 c) 2 d) 3
Explanation: Each hydrogen atom has a single electron in its valence shell and as a result can form only one bond. It cannot form a double bond as it does not have the necessary electrons to share.
- What is the maximum number of double bonds that a carbon atom (C) can form?
a) 4 b) 1 c) 2 d) 0
Explanation: Each carbon atom has 4 valence electrons that it can share with other atoms. Since each double bond corresponds to a pair of electrons, the carbon atom can form only 2 double bonds.
- Given the electronegativities below, which covalent single bond is most polar?
a) C-H b) N-H c) O-H d) O-N
Explanation: Bond polarity can be judged based on the differences between the electronegativities of the atoms involved. Of the available choices, the bond between O and H will have the largest electronegativity difference making it the most polar bond in this group.
- The ion ICI 4 -^ has __________ valence electrons.
a) 34 b) 36 c) 35 d) 28
Explanation: valence electrons A = (7×1) +(7×1) +1 = 36
