CHEM 2261: structures and bond
Practice 2 Questions with Complete
Answers.
which of the following statements correctly describe the basic principle of VSEPR theory? -
Answer each group around a central atom is located as far from the others as possible
Rank the following bonds in order of increasing bond length (shortest to longest), based on
periodic trends, starting with the shortest bond at the top of the list?
H-F
H-Se
H-O
H-S - Answer H-F
H-O
H-S
H-Se
when does bond length increase? decrease? - Answer down a group
across a period
the geometry around an atom is determined by the number of groups of electrons surrounding
the atom. Match each geometry with the correct number of groups:
2 groups
3 groups
4 groups - Answer (2) linear
(3) trigonal planar
(4) tetrahedryl
Correctly order the steps necessary to determine the geometry around a given atom. - Answer
1. Draw a valid Lewis structure
2. count groups around a given atom
3. Match the number of groups with the associated geometry
, three- dimensional systems are represented in o chem using the wedge-dash format. Match
each type of line with the correct description.
- solid line
- wedge
- dashed line - Answer - a bond in the plane
- a bond in front of the plane
- a bond behind the plane
match each shape to correct bonding motif:
- trigonal pyramid
- tetrahedral
- bent - Answer - an atom surrounded by 3 bonding pairs, and 1 lone pair
- am atom surrounded by 4 bonding pairs
- an atom surrounded by 2 bonding pairs, and 2 lone pairs
when drawing a condensed structure of an organic compound, multiple bond lines are usually
_______ while single bond lines are often _______ - Answer included
omitted
In the skeletal structure for an organic compound, it is assumed that there is a ___________
atom at the end of any line and at the junction of any two lines. This type of structure omits all
_______ atoms except those directly bonded to a heteroatom. - Answer
which of the following correctly describe the conventions used when drawing a skeletal
structure for an organic compound? - Answer - it is assumed that every carbon atom has
enough hydrogens to make it tetravalent
- all heteroatoms are drawn and the hydrogens directly bond to them
- the unlabeled end of a line represents a C atom
when interpreting skeletal structures of charges species, the number of lone pairs on a
particular atom depends on the charge on the atom. Match each charge with the number of
lone pairs present on the relevant atom
- no lone pairs
- one lone pair
- three lone pairs - Answer - a carbon atom with a positive charge (and 3 bonds)
Practice 2 Questions with Complete
Answers.
which of the following statements correctly describe the basic principle of VSEPR theory? -
Answer each group around a central atom is located as far from the others as possible
Rank the following bonds in order of increasing bond length (shortest to longest), based on
periodic trends, starting with the shortest bond at the top of the list?
H-F
H-Se
H-O
H-S - Answer H-F
H-O
H-S
H-Se
when does bond length increase? decrease? - Answer down a group
across a period
the geometry around an atom is determined by the number of groups of electrons surrounding
the atom. Match each geometry with the correct number of groups:
2 groups
3 groups
4 groups - Answer (2) linear
(3) trigonal planar
(4) tetrahedryl
Correctly order the steps necessary to determine the geometry around a given atom. - Answer
1. Draw a valid Lewis structure
2. count groups around a given atom
3. Match the number of groups with the associated geometry
, three- dimensional systems are represented in o chem using the wedge-dash format. Match
each type of line with the correct description.
- solid line
- wedge
- dashed line - Answer - a bond in the plane
- a bond in front of the plane
- a bond behind the plane
match each shape to correct bonding motif:
- trigonal pyramid
- tetrahedral
- bent - Answer - an atom surrounded by 3 bonding pairs, and 1 lone pair
- am atom surrounded by 4 bonding pairs
- an atom surrounded by 2 bonding pairs, and 2 lone pairs
when drawing a condensed structure of an organic compound, multiple bond lines are usually
_______ while single bond lines are often _______ - Answer included
omitted
In the skeletal structure for an organic compound, it is assumed that there is a ___________
atom at the end of any line and at the junction of any two lines. This type of structure omits all
_______ atoms except those directly bonded to a heteroatom. - Answer
which of the following correctly describe the conventions used when drawing a skeletal
structure for an organic compound? - Answer - it is assumed that every carbon atom has
enough hydrogens to make it tetravalent
- all heteroatoms are drawn and the hydrogens directly bond to them
- the unlabeled end of a line represents a C atom
when interpreting skeletal structures of charges species, the number of lone pairs on a
particular atom depends on the charge on the atom. Match each charge with the number of
lone pairs present on the relevant atom
- no lone pairs
- one lone pair
- three lone pairs - Answer - a carbon atom with a positive charge (and 3 bonds)
