Chapter 4; Molecular Geometry, Polarity, And Intermolecular Forces Of Attraction

Question 1

what is electron geometry

Answer 1

relative position of the groups of electrons on the central atom

Question 2

what groups does the electron geometry include

Answer 2

single bond
double bond
a triple bond
a nonbonding pair

Question 3

what is molecular geometry

Answer 3

relative position of the atoms in a molecule; determine by the electron geometry

Question 4

what does the VSEPR theory predict about groups of electrons

Answer 4

predicts that groups of electrons on the central atom are oriented to maximize distance between them

Question 5

depending on the number of groups of electrons what are main three names

Answer 5

two groups; linear
three groups; trigonal planar
four groups; tetrahedral

Question 6

what are the angles for a linear, trigonal planar, and tetrahedral group

Answer 6

linear - 180
trigonal planar - 120
tetrahedral - 109.5

Question 7

what is molecular geometry determined by

Answer 7

based on the number of bonding versus nonbonding groups on the central atom

Question 8

what is the electron and molecular geometry for 2 electron groups

Answer 8

electron - linear
molecular - linear

Question 9

what is the electron and molecular geometry for 3 electron groups

Answer 9

electron - trigonal planar
molecular - trigonal or bent (2 bonding and 1 nonbonding group)

Question 10

what is the electron and molecular geometry for 4 electron groups

Answer 10

electron - tetrahedral
molecular - tetrahedral, trigonal pyramidal (3 bonding and 1 nonbonding groups), or bent (2 bonding and 2 nonbonding groups)

Question 11

how to find a molecular bond angle

Answer 11

angle (0 - 360)

Question 12

what is molecular polarity

Answer 12

• determines how molecules interact with each other at the molecular level
• molecular level interactions determine their macroscopic properties

Question 13

what is a covalent bond

Answer 13

two atoms sharing valence electrons

Question 14

is sharing valence electrons always equal in covalent bonds

Answer 14

no; one atoms may attract the electrons in a bond more closely towards it nucleus

Question 15

what is electronegativity

Answer 15

ability of an atom, when part of a covalent bond, to draw electrons towards its nucleus

Question 16

as the atomic # increases what happens to the protons and electrons

Answer 16

atomic # increases = more protons in atoms = attract electrons

Question 17

what does negativity attract.
what does positive attract

Answer 17

negative attracts positive
positive attracts negative

Question 18

in the periodic table which ways does electronegativity increase in the periodic table

Answer 18

down to up
left to right

Question 19

when increasing electronegativity do the atoms get smaller or bigger

Answer 19

smaller
as go down a group it adds energy levels, so the electron cloud gets bigger = further away the less get pulled to nucleus

Question 20

what determines if a bond is polar or non polar

Answer 20

electronegativity differences

Question 21

in an electron density diagram that shows polar and non polar molecules, what color is high density

Answer 21

red

Question 22

in an electron density diagram that shows polar and no polar molecules what color is low density

Answer 22

blue

Question 23

in an electron density diagram that shows polar and non polar molecules, what color is neutral

Answer 23

green to yellow

Question 24

atom with a greater electron density has a partial negative charge

Answer 24

s^-

Question 25

atom with a lesser electron density has a partial positive charge

Answer 25

s^+

Question 26

what is a dipole

Answer 26

separation of partial charges

Question 27

what type of covalent bonds are used with dipoles

Answer 27

polar bonds

Question 28

what are some facts about non polar bonds regarding electronegativity

Answer 28

• form between atoms of similar electronegativity
• even electron distribution
• no partial charges or dipoles

Question 29

if there is a electronegativity difference of 0.5 and less (x<0.5) what does this make it

Answer 29

non polar covalent bond

Question 30

if there is an electronegativity difference of greater than 0.5 and less than 2.0 (0.5<x>2.0), what does this make it</x>

Answer 30

polar covalent bond

Question 31

if there is an electronegativity difference of greater than 2.0 (x>2.0), what does this make it

Answer 31

ionic bond

Question 32

can entire molecules be polar and non polar

Answer 32

yes

Question 33

how can entire molecules be polar or nonpolar

Answer 33

polar molecules have overall charge separation
non polar molecule have even distribution of electros
- side note; polar and non polar molecules have very different physical and chemical properties

Question 34

a non polar molecule can be a molecular with all […] bonds, or a molecule with […] geometry and […] polar bonds/bond dipoles

Answer 34

non polar
symmetrical
identical

Question 35

non polar molecules with non polar bonds

Answer 35

hydrocarbon compounds
diatomic elements

Question 36

non polar molecules with polar bonds

Answer 36

• identical polar bonds in symmetrical molecules
• bond dipoles cancel
• three symmetrical shapes; linear, trigonal planar and tetrahedral

Question 37

a molecule is non polar if
1. all the bonds are […] or
2. the […] geometry is […] (the central atom has no nonbonding electrons) AND all the bonds are […}

Answer 37

nonpolar
molecular
symmetrical

Question 38

a polar molecule can be
- a molecule with one […] bond
- a molecule with […] molecular geometry and more than […] polar bond
- a molecule with […] molecular geometry and nonidentical polar bonds

Answer 38

polar
nonsymmetrical
one
symmetrical

Question 39

what is a covalent bond

Answer 39

result of intramolecular forces of attraction

Question 40

what are intermolecular forces of attraction

Answer 40

attractions between molecules in liquid and solid states

Question 41

intermolecular bonds are weaker than

Answer 41

covalent bonds

Question 42

intermolecular and intermolecular forces of attraction determine […] properties of a compound; […],[…],[…]

Answer 42

physical
boiling point
melting point
solubility

Question 43

do polar molecules have permanent or temporary dipoles

Answer 43

permanent

Question 44

do non polar molecules have permanent or temporary dimples

Answer 44

can form temporary

Question 45

intermolecular forces of attraction form between a […] charge on one molecule and the […] partial charge on another

Answer 45

partial
opposite

Question 46

what is the order of the types of intermolecular forces of attraction from weakest to strongest

Answer 46

dispersion forces (or London forces)
dipole - dipole forces
hydrogen bonding

Question 47

dispersion forces - or London forces are…

Answer 47

• common to all compounds and elements
• also called London forces
• weakest intermolecular force of attraction and * only one available for non polar compounds *

Question 48

how does a dispersion force form

Answer 48

electrons in a non polar compound may shift, forming a temporary dipole
- temporary dimple induces another temporary dipole in a nearby molecule
- weak attraction between temporary dipole and induced dipole = dispersion force

Question 49

compounds with larger molecules have […] dispersion forces than compounds with smaller molecules

Answer 49

stronger
propane (C3H8) > methane (CH4)
(more opportunities for electrons to shift)

Question 50

elements with larger atoms have […] dispersion forces than elements with smaller molecules

Answer 50

Iodine (I2) > fluorine (F2)

Question 51

dispersion forces are (core concept)

Answer 51

• the only forces of attraction in elements and non polar compounds
• dispersion forces result from induced temporary dipoles

Question 52

what are dipole dipole forces

Answer 52

• form between oppositely charged ends of polar molecules
• form between permanent dipoles
• are stronger than dispersion forces

Question 53

dipole dipole intermolecular forces …

Answer 53

• exist between polar molecules that have a permanent dipole
• they are stronger than dispersion forces

Question 54

hydrogen bonding forces are dipole dipole forces between molecules with […] bond dipoles, which are

Answer 54

H-F
H-O
H-N
form between the partial positive pole of one molecule (H) and partial negative pole of another (F, O, N)

Question 55

how to depict a hydrogen bonding force

Answer 55

use dotted line between H (one molecule) and N,O, or F (another molecule) or dashes
e.g. H-F …. H-F
there is donor and receptor

Question 56

how to determine the strongest intermolecular force of attraction

Answer 56

are polar molecules present
no - dispersion force
yes = are H-O H-N or H-F bonds present
no - dipole dipole forces
yes - hydrogen bonding forces
side note;
in a molecule with hydrogen bonding forces can also have dispersion forces

Question 57

what are the intermolecular forces of molecules that are bonded to H such as F, O, N

Answer 57

hydrogen bonding

Question 58

what are the intermolecular forces of attraction of molecules that are polar

Answer 58

• dipole dipole
• London dispersion forces

Question 59

what are the intermolecular forces of attraction in molecules that are non polar
side note; molecules that contain only C and H are non polar

Answer 59

London dispersion forces