CHEM 2261: structures and bond Practice 2

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

(2) linear (3) trigonal planar (4) tetrahedryl

an sp2 orbital has _______% s character and ________% p character.

- 33 - 67

which of the following bonds are nonpolar? - B-H - S-H - S-C - C-Cl - N-Cl

- B-H - S-H - S-C - N- Cl

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

- a bond in the plane - a bond in front of the plane - a bond behind the plane

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

- a carbon atom with a positive charge (and 3 bonds) - a carbon atom with a negative charge (and 3 bonds - an oxygen atom with a negative charge (and one bond)

select all statements that correctly describe a pi bond:

- a multiple bond always contains at least one pi bond - a pi bond is formed by the side by side overlap of two p orbitals

match each shape to correct bonding motif: - trigonal pyramid - tetrahedral - bent

- 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

a bond dipole can be indicated with a(n) ________ that points toward the most electronegative element. The separation of charge can also be depicted with delta positive and delta _______ signs to indicate the unequal sharing of electron density.

- arrow - negative

which of the following statements correctly describe a sigma bond?

- cylindrically symmetrical - all single bonds

as the number of shared electrons between two nuclei increases, the bond length _____ and the bond strength ________.

- decreases - increases

the number of hybrid orbitals formed from the hybridization of atomic orbitals is ____ the number of orbitals mixed, each having ______ and energy

- equal to - same shape

the number of _____ around a given atom corresponds to the number of ______ orbitals that must be hybridized to form the hybrid orbitals.

- groups - atomic

the mathematical process of mixing atomic orbitals from a specific atom is called the ____ of orbitals and the new atomic orbitals formed are referred to as _____ orbitals.

- hybridization - hybrid

which of the following correctly describe the conventions used when drawing a skeletal structure for an organic compound?

- 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

a group of sp3 hybrid orbitals is formed by the hybridization of ______s and ______p orbitals from the same principle energy level. These hybrid orbitals have the same shape, are equal in energy, and are arranged in a(n) geometry.

- one - three - tetrahedral

match the correct atomic orbitals used to form the appropriate hybrid orbitals: - sp hybrid orbitals - sp2 hybrid orbitals

- one s orbital and one p orbital - one s orbital and two p orbitals

a covalent bond in which the electrons are shared unequally is called a ___________ covalent bond. The bond is said to have a permanent _____, which is a separation of charge.

- polar - dipole

match the bond polarity with the correct molecular polarity - contain one polar bond, or two or more bond dipoles that reinforce each other - contain no polar bonds, or two or more bond dipoles that cancel

- polar molecules - nonpolar molecules

which of the following statements correctly describe a C-F bond.

- the bond dipole should point towards F - Carbon should be marked with a delta + symbol

which of the following statements correctly describe sp3 hybrid orbitals?

- the hybridization of one s and three p orbitals forms four sp3 hybrid orbitals - an sp3 hybrid orbital has one small and one large lobe - the 4 sp3 hybrid orbitals are intermediate in energy between the s and p orbitals from which they were formed

match the number and type of hybrid orbitals of an atom with the correct number of specific groups surrounding them - 1 triple bond and 1 lone pair - 1 double bond and 2 sigma bonds - 2 lone pairs and 2 sigma bonds

- two sp hybrid orbitals - three sp2 hybrid orbitals - four sp3 hybrid orbitals

Correctly order the steps necessary to determine the geometry around a given atom.

1. Draw a valid Lewis structure 2. count groups around a given atom 3. Match the number of groups with the associated geometry

explain why CO2 is a nonpolar molecule.

CO2 is linear and therefore the individual bond dipoles cancel to give no net dipole

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

H-F H-O H-S H-Se

when does bond length increase? decrease?

down a group across a period

which of the following statements correctly describe the basic principle of VSEPR theory?

each group around a central atom is located as far from the others as possible

when drawing a condensed structure of an organic compound, multiple bond lines are usually _______ while single bond lines are often _______

included omitted

a bond between two atoms of identical or similar electronegativity is a ________.

nonpolar covalent bond

multiple bonds only contain one ______ bond

sigma

which of the following defines the ground state of an atom?

the lowest energy state of an atom, where all electrons are in the lowest energy levels possible