Chapter 10: Chemical Bonding II: Molecular Shapes, Valence Bond Theory, and Molecualr Orbital Theory Flashcards Preview

CHEM 1120 > Chapter 10: Chemical Bonding II: Molecular Shapes, Valence Bond Theory, and Molecualr Orbital Theory > Flashcards

Flashcards in Chapter 10: Chemical Bonding II: Molecular Shapes, Valence Bond Theory, and Molecualr Orbital Theory Deck (61):
1

Define electron groups

A general term for lone pairs, single bonds, multiple bonds, or lone electrons in a molecule

2

According to VESPR theory what do the repulsions between electron groups on interior atoms of a molecule determine?

The geometry of the molecule

3

The preferred geometry of a molecule is the one which electron groups have the _____ separation (and therefore _____ energy) possible

Maximum
Minimum

4

For molecules that have just one interior atom (the central atom), what two things does the the molecular geometry depend on?

1. The number of electron groups around the central atom
2. How many of those electron groups are bonding groups and how many are lone pairs

5

What is the electron geometry for two electron groups?

Linear geometry

6

What are the angles between the two electron group in linear geometry

180°

7

Is a double bond still one electron group?

Yes

8

Linear geometry can be observed in all molecules that have....

Two electron groups and no lone pairs

9

What electron geometry forms with 3 electron groups?

Trigonal planar

10

What angle for trigonometry planar geometry maximizes the electron groups separation?

120°

11

Electron geometry, the geometry predicted by VESPR theory, is ______

Idealized

(This means that it is close but not the same as the geometry found experimentally)

12

What is the electron geometry for four electron groups?

Tetrahedral geometry

13

What are the ideal angles of tetrahedral geometry?

109.5°

14

What is the geometry for five electron groups?

Trigonal bipyramidal geometry

15

What are the angles like for trigonal bipyramidal geometry?

The angles between the equatorial positions (the three bonds in the trigonal plane) are 120°, while the angle between the axial positions (the two bonds on either side of the trigonal plane) and the trigonal plane is 90°

16

What is the electron geometry for 6 electron groups?

Octahedral geometry

17

Define valance shell electron pair repulsion theory (VSEPR theory)

A theory that allows prediction of the shapes of molecules based on the idea that electrons—either as lone pairs or bonding pairs—repel one another

18

What are the angles for octahedral geometry?

All angles are 90°

19

Define electron geometry

The geometrical arrangement of electron groups in a molecule

20

Define molecular geometry

The geometrical arrangement of atoms in a molecule

21

Lone pairs take up ____ than bonding pairs

More

22

What is the molecular geometry of a molecule with 4 electron groups, with one of them being a lone pair?

Trigonal pyramidal

23

What is the molecular geometry of a molecule with 4 electron groups, with two of them being a lone pairs?

Bent

24

Lone pair–lone pair repulsion is _____ than lone pair–bonding pair repulsion which is _____ than bonding pair–bonding pair repulsion

Greater
Greater

25

Lone pairs ____ occupy axial positions

Never

26

What is the molecular geometry of a molecule with 5 electron groups, with one of them being a lone pair?

Seesaw

27

What is the molecular geometry of a molecule with 5 electron groups, with two of them being a lone pairs?

T-shaped

28

What is the molecular geometry of a molecule with 5 electron groups, with three of them being a lone pairs?

Linear

29

What is the molecular geometry of a molecule with 6 electron groups, with one of them being a lone pair?

Square pyramidal

30

What is the molecular geometry of a molecule with 6 electron groups, with two of them being a lone pairs?

Square planar

31

How can you determine the number of electron groups

From the Lewis structure

32

A straight line is....?
A hashed wedge is...?
A solid wedge is...?

Bond in the plane of the paper
Bond going into the page
Bing coming out of the page

33

If a diatomic molecule has a polar bond, is the whole molecule polar?

Yes

34

If the bond in a diatomic molecule is nonpolar, the molecule as a whole will be ______

Nonpolar

35

If the molecular geometry is such that the dipole moments of idividual polar bonds sum together to a net dipole moment the the molecule will be ____

Polar

36

It the molecular geometry is such that the dipole moments of the individual polar bonds cancel each other (that is, sum to zero), then the molecule will be _____

Nonpolar

37

Wether or not a polyatomic molecule will be polar or nonpolar (if it contains polar bonds) depends completely upon...?

The molecular geometry of the molecule

38

Polar molecules mix ___ with other polar molecules but mix ____ with nonpolar molecules

Well
Badly

39

Define valance bond theory

An advanced model of chemical bonding in which electrons reside in quantum-mechanical orbitals localized on individual atoms that are a hybridized blend of standard atomic orbitals; chemical bonds result from an overlap of these orbitals

40

The energy of interaction is usually _____ (or _____) when the interacting atomic orbitals contain a total of two electrons that can spin pair

Negative
Stabilizing

41

In valance bonding theory, what do the atoms in a molecule reside in?

Quantum-mechanical atomic orbitals

(Such as s,p,d,f and hybrid combinations of these)

42

In valence bond theory, Which two ways can a covalent bond occur?

When two half-filled orbitals with spin pairing of the two valence electrons
Or less commonly, the overlap of a completely filled orbital with an empty orbital

43

In valance bond theory, what determines the shape of the molecule?

The geometry of the overlapping orbitals

44

Define hybridization

A mathematical procedure in which standard atomic orbitals are combined to form new, hybrid orbitals

45

Define hybrid atomic orbitals (hybrid orbitals)

Orbitals formed from the combination of standard atomic orbitals that correspond more closely to the actual distribution of electrons in chemically bonded atom

46

Are hybrid orbitals still located on individual atoms? What is the difference between orbitals and hybrid orbitals

Yes
Hybrid orbitals are different shapes and energies than standard atomic orbitals

47

Hybrid orbitals _____ the energy of the molecule by _____ the orbital overlap in a bond

Minimize
Maximizing

48

What does the standard number of atomic orbitals added together always equal?

The number of hybrid orbitals formed

(ie total number of orbitals is conserved)

49

What does the particular combination of standard atomic orbitals added together determine?

The shape and energy of the hybrid orbitals formed

50

Tendency to hybridize _____ with the number of bonds formed

Increases

51

What does the hybridization of one s orbital and three p orbitals result in?

Four sp3 hybrid

52

What does the hybridization if one s and two p orbitals result in?

Three sp2 hybrids and one leftover UN hybridized p orbitals

53

What does the hybridization of one s and one p orbital result in?

Two sp orbitals and two left over unhybridized p orbitals

54

Define Pi bond

The bond that forms between two p orbitals that overlap side to side

55

Which bond is stronger sigma or Pi?

Sigma

56

Why do Pi bonds make rotation impossible?

you have to break the bond to rotate

57

define sigma bond

The resulting bond that forms between a combination of any two s,p or hybridized orbitals that overlap end to end

58

in general sigma bonds are ____ than pi bonds

stronger

59

what is the hybridization of linear geometry?

sp ( + 2 unhbridized p)

60

what is the hybridization of trigonal planar?

sp2 ( + 1 unhbridized p)

61

what is the hybridization of tetrehedral?

sp3