1. Shape and Drawing ; Bonding-Hybridization and Bonding-Resonance

Question 1

what are Lewis structures and why are they important?

Answer 1

-diagrams that represent the valence electrons of atoms within a molecule

-help determine molecular shape

Question 2

what are the steps to draw a Lewis structure?

Answer 2

1. find the total number of valence electrons
2. put the least electronegative atom in the middle
3. form electrons between atoms
4. fulfill the octet rule
5. move electrons from outer atoms to inner atoms to help fulfill the octet rule

Question 3

what is the trend of electronegativity on the periodic table?

Answer 3

less electronegativity moving from right to left or down a collumn

Question 3

what is the formula to find the formal charge?

Answer 3

FC=# of valence electrons - (lone pairs + # of bonds)

Question 4

how many bonds does hydrogen make?

Answer 4

one

Question 5

how many bonds does Boron make?

Answer 5

three

Question 6

which atom mainly makes five bonds?

Answer 6

phosphorus

Question 7

which atom mainly makes six bonds?

Answer 7

sulphur

Question 8

what is a trick to remember the number of bonds an atom typically makes?

Answer 8

the ones digit in the number above the column

Question 9

what are the models to explain chemical bonds? (5)

Answer 9

Lewis dot structure, valence shell electron repulsion theory, valence bond theory, hybridization, molecular orbital theory

Question 10

what is the angle of a linear molecular shape?

Answer 10

180

Question 11

what is the angle of a trigonal planar molecular shape?

Answer 11

120

Question 12

what is the angle of a tetrahedral molecular shape?

Answer 12

109.5

Question 13

what is the angle of a trigonal bipyramidal molecular shape?

Answer 13

120 and 90

Question 14

what is the angle of an octahedral molecular shape?

Answer 14

90

Question 15

how is the valence bond theory distinct from the other chemical bond models?

Answer 15

shows how the overlap of incompletely filled atomic orbitals forms bonds

Question 16

how many pi bonds are in a triple bond?

Answer 16

two

Question 17

what do sigma bonds and lone pairs require?

Answer 17

sp hybridized orbitals

Question 18

what is a sigma bond?

Answer 18

a single bond

Question 19

what happens to the strength of a bond if the bond length increases?

Answer 19

the bond strenth decreases

Question 20

what is a delocalized system?

Answer 20

a molecule where its lone pairs and multiple bonds can be moved

Question 21

what is a resonance structure?

Answer 21

when a molecule can be represented using two or more other structures

Question 21

what are the characteristics of better resonance structures? (4)

Answer 21

-has more bonds

-does not violate the octet rule

-fewer formal charges

-charges correctly distributed according to electronegativity

Question 22

how is the VESPR theory distinct from the other chemical bond models?

Answer 22

emphasizes that regions of negative charge will repel each other creating a shape used to predict hybridization

Question 23

why are imperfect angles formed?

Answer 23

-when a less-than-ideal geometry is formed because of the presence of a ring

-repulsion of electron lone pairs

Question 24

what are polar bonds? (2)

Answer 24

-if there is a bond between two electrons, one atom in the bond is more electronegative than the other

-electronegativity difference greater than 0.4

Question 25

what are the characteristics of polar molecules?

Answer 25

-at least one polar bond

-appropriate geometry

Question 26

what are intermolecular forces?

Answer 26

the attractive and repulsive forces within a molecule

Question 26

when do dipole moments cancel out?

Answer 26

if two dipole arrows are perfectly opposite from one another

Question 27

why are intermolecular forces considered?

Answer 27

to get a sense of a molecule’s boiling and melting point

Question 28

what are the intermolecular forces listed from weakest to strongest?

Answer 28

Van Der Waals, dipole dipole, hydrogen bond, ionic bond

Question 29

what does a bigger molecule with more atoms do to the melting or boiling point?

Answer 29

increases it

Question 29

what does a strong intermolecular force do to the boiling or melting point?

Answer 29

increases it

Question 30

what does a branched molecule do to the melting or boiling point?

Answer 30

decreases it

Question 31

how is the molecular orbital theory distinct from the other chemical bond models?

Answer 31

two atomic orbitals interacting to make a bond