Section 9.2- Shapes and Properties of Molecules

Question 1

knowing the _________________ of the elements allows us to predict how they will combine to form covalent substances

Answer 1

Lewis structures

Question 2

Lewis structures do not give the correct result because SO2 contains a pair of ___________________________– electrons that circulate freely through the molecule instead of being bound to a single atom or pair of atoms

Answer 2

delocalized electrons

Question 3

a bonding situation in which electrons are shared by more than two atoms is called

Answer 3

delocalization

Question 4

the actual structure of a molecule with delocalized electrons cannot be accurately represented by a single Lewis structure but is intermediate between _______________________________

Answer 4

all valid Lewis structures (resonance forms)

Question 5

delocalization is often called ________________ because it is often convenient to approximate the molecule’s structure as rapidly changing

Answer 5

resonance

Question 6

since electrons are negatively charged, they tend to

Answer 6

repel each other

Question 7

the theory that uses the prediction that the bonding and nonbonding electron pairs in the valence shell of the central atom in a molecule tend to get as far apart as possible to predict the shapes of molecules

Answer 7

valence-shell electron-pair revulsion (VSEPR)

Question 8

group of elements that has the most possible bonds around it

Answer 8

group 4

Question 9

the farthest apart four electron pairs (or four of anything) can get geometrically is at the corners of a

Answer 9

tetrahedron

Question 10

the bond angles of a tetrahedron are about

Answer 10

109.5 *

Question 11

the structure of methane, with four bonding pairs around the carbon atoms, is

Answer 11

tetrahedral

Question 12

only the ______________ of atoms desccribe the molecule’s shape

Answer 12

positions

Question 13

nonbinding pairs repel _________ than bonding pairs and take up ________ space

Answer 13

more
more

Question 14

hydrogen and oxygen atoms have an ______________ geometry since only atoms describe the shape of the molecule

Answer 14

angular molecule

Question 15

the farthest apart that two electrons can get is 180 degrees, making a

Answer 15

linear molecule

Question 16

the geometry that allows three electron pairs to get as far apart as possible is the

Answer 16

trigonal planar (120)

Question 17

whenever electrons in a covalent bond are shared unequally, the bond will be

Answer 17

polar

Question 18

determining whether or not a molecule is a _____________ is important for deciding what forces of attraction may exist between molecules– forces that affect many properties of substances

Answer 18

polar molecule

Question 19

a molecule that has a symmetrical distribution of polar bonds will have no net dipole and will be

Answer 19

nonpolar

Question 20

individual bond dipoles will cancel each other out if they are of

Answer 20

equal polarity