Chapter 9

Question 1

Covalent bonds

Answer 1

Atoms share electrons

Occur between nonmetal atoms

Question 2

Octet rule

Answer 2

atoms are stabilized by having eight electrons in their valence shell
four pairs of electrons

Question 3

Lewis structures

Answer 3

show the arrangement of covalently bonded atoms

Question 4

Lone pair

Answer 4

a pair of unshared electrons

Question 5

Drawing lewis structure steps

Answer 5

1) add up all the valence electrons
use periodic table group numbers to determine nuber of valence electrons
2)Frame the structure with single bonds
the atom closer to the lower left of the periodic table is the atom in the center. hydrogen is never in the center.
3) Fill the octets on outer atoms first
4) Fill the octet on the central atom
place any remaining electrons on the central atom
use double or triple bonds to fulfill the octet rule of the central atom

Question 6

Polyatomic ions

Answer 6

groups of atoms with an overall charge

Question 7

Formal charges

Answer 7

method of identifying charged sites
not perfect indicator of charge on an atom
but good tool for keeping track of overall charge of molecule or ion
assumes atoms share equally

Question 8

How to calculate formal charge (formal charge = )

Answer 8

of valence electrons in the neutral atom - # of covalent bonds - # of unshared electrons

Question 9

Drawing lewis structures for polyatomic ions

Answer 9

similar to neutral atoms

consider the charge when finding the # of valence electrons (wether it increases or decreases the amount of electrons)

Question 10

When there is more than one option on how to structure a lewis structure, generally, what is the best

Answer 10

the best are generally the ones that minimize the charge values or have zero values for all of the atoms

Question 11

Valence Shell Electron Pair Repulsion (VSEPR)

Answer 11

key idea: groups of electrons repel each other. in molecules electron groups will be as far away from each other as possible

Question 12

Two ways we describe atom geometries

Answer 12

Electronic geometry- the arrangement of electrons around a central atom
Molecular geometry- the arrangement of atoms within a molecule/ shape caused by the arrangement of atoms

Question 13

Molecular geometry

Answer 13

the arrangement of atoms within a molecule

also known simply as shape, depends on the electronic geometry but only considers the location of the atoms

Question 14

Two electron sets:

Two bonding sets, 0 lone pairs

Answer 14

Electronic geometry: Linear
Bond angle of 180 degrees
Molecular geometry: Linear
Bond angle of 180 degrees

Question 15

“Sets” of electrons

Answer 15

single, double, or triple bonds all count as one “set” of electrons

Question 16

Three electron sets, if the three sets are attached to atoms ( 0 lone pairs)
(Three bonding sets, 0 lone pairs)

Answer 16

Electronic geometry: Trigonal planar
Molecule is flat and has a bond angle of 120 degrees
Molecular geometry: Trigonal planar
Molecule is flat with a bond angle of 120 degrees

Question 17

Three electron sets, two sets attached to atoms and one as a lone pair
(Two bonding sets, one lone pair)

Answer 17

Electronic geometry: Trigonal planar
Molecule is flat and has a bond angle of 120 degrees
Molecular geometry: Bent

Question 18

Four electron sets, if four sets are attached to atoms ( 0 lone pairs)
(Four bonding sets, 0 lone pairs)

Answer 18

Electronic geometry: Tetrahedral
Bond angle of 109.5 degrees
Molecular geometry: tetrahedral
occupies a 3D volume

Question 19

Four electron sets, three attached to atoms, one as a lone pair
(Three bonding sets, one lone pairs)

Answer 19

Electronic geometry: Tetrahedral

Molecular geometry: trigonal pyramidal (pyramid shape)

Question 20

Four electron sets, two attached to atoms, two as lone pairs

Two bonding sets, two lone pairs

Answer 20

Electronic geometry: Tetrahedral

Molecular geometry: Bent

Question 21

Polar covalent bonds

Answer 21

atoms do not share electrons equally

Question 22

ways to depict polar covalent bonds’s charge

Answer 22

delta + above the positive atom, delta minus over the negative
An arrow, pointing in the direction the electrons are pulled (the more electronegative side) with a small cross on the back end of the arrow to indicate the positive charge

Question 23

Electronegativity

Answer 23

Measure of how strongly atoms pull bonded electrons

Question 24

Pattern of electronegativity change on the periodic table

Answer 24

increases from left to right, consistent to what we know from ionic bonds, metals to the L of the table loose electrons easily while nonmetals on the R tend to pull or gain electron
also increases as you go up a column (group)

Question 25

Difference in atom electronegativity range

Answer 25

Covalent: < 0.5
Polar covalent: 0.5-2.0
Ionic: >2.0

Question 26

Molecular dipole (net dipole/ dipole)

Answer 26

Overall polarity in a molecule

Question 27

finding net pole of a molecule

Answer 27

add together the pole of each polar covalent bond

Question 28

how shape effects function

Answer 28

h2o in liquid form sticks together bc the atoms are attracted to each other bc of their net dipoles