Chapter 5 - Chemical Bonding

Question 1

How do you name molecular compounds?

Answer 1

Greek prefix to shown no. of atoms in first element
Name of first element
Greek prefix to show no. of atoms in second element
add ‘ide’ to second element

Question 2

What is the Greek prefix for 1?

Answer 2

mono

Question 3

What is the Greek prefix for 2?

Answer 3

di

Question 4

What is the Greek prefix for 3?

Answer 4

tri

Question 5

What is the Greek prefix for 4?

Answer 5

tetra

Question 6

What is the Greek prefix for 5?

Answer 6

penta

Question 7

What is the Greek prefix for 6?

Answer 7

hexa

Question 8

What is the Greek prefix for 7?

Answer 8

hepta

Question 9

What is the Greek prefix for 8?

Answer 9

octa

Question 10

What is the Greek prefix for 9?

Answer 10

nona

Question 11

What is the Greek prefix for 10?

Answer 11

deca

Question 12

What is H2O?

Answer 12

Water

Question 13

What is N2H4?

Answer 13

Hydrazine

Question 13

What is H2O2?

Answer 13

hydrogen peroxide

Question 14

What is NH3?

Answer 14

Ammonia

Question 15

What is C2H2?

Answer 15

Acetylene

Question 16

What is PH3?

Answer 16

Phosphine

Question 17

What is AsH3?

Answer 17

Arsine

Question 18

What is NO?

Answer 18

Nitric oxide

Question 19

What is N2O?

Answer 19

Nitrous Oxide

Question 20

What is CH4?

Answer 20

Methane

Question 21

When do Covalent bonds form?

Answer 21

when valence electrons are shared to provide each atom with a full octet

Question 22

What are electrons shared by covalently bonding called?

Answer 22

bonding electrons

Question 23

How do you draw more complex covalent bonds?

Answer 23

1. adding up of all the valence electrons
2. pick a central atom, arrange other atoms around central atom, connect w/ single bond
3. fill the octets of outer atoms, left over electrons fill octet of central atom
4. if octets aren’t filled try multiple bonds

Question 24

What does the Lewis model account for?

Answer 24

Why particular combinations of atoms form molecules and others do not Hydrogen and the halogens are all diatomic molecular elements oxygen generally forms either 2 single bonds or a double bond in its molecular compounds

Question 25

What are the Lewis Models limitations?

Answer 25

bonding electrons depicted as typically shared between atoms (often not the case)

Question 26

What is electronegativity?

Answer 26

the ability of an atom to attract bonding electrons to itself increases across period (left to right) and decreases down group (top to bottom) The larger the difference in electronegativity, the more polar the bond

Question 27

What does electronegativity values go from?

Answer 27

0.7 to 4.0

Question 28

What is lowest electronegativity?

Answer 28

0.7 Francium

Question 29

What is the highest electronegativity?

Answer 29

4.0 Fluorine

Question 30

In polar covalent bonds the end with more electron density gets a what?

Answer 30

partial negative charge (and vice versa)

Question 31

Electronegativity of 0-0.4 is what type of bond?

Answer 31

covalent

Question 32

Electronegativity of 0.4-2.0 is what type of bond?

Answer 32

Polar Covalent

Question 33

Electronegativity of 2.0+ is what type of bond?

Answer 33

Ionic

Question 34

What are resonance results?

Answer 34

when we can draw more than one Lewis Structure

Question 35

What is a resonance hybrid?

Answer 35

intermediate between multiple resonance structures; average of the possible Lewis Structures

Question 36

What is formal charge?

Answer 36

fictitious charge assigned to each atom in a Lewis Structure if all bonding electrons were shared equally results from a kind of electron 'bookkeeping'

Question 37

What is the goal of formal charge calculation?

Answer 37

sum of formal charges in neutral molecule must be zero sum of formal charges in ion must equal charge of ion every atom should have a formal charge of 0 if possible negative charge if any should be on most electronegative atom

Question 38

How do you calculate formal charge?

Answer 38

no. of valence electrons - (no. of non bonding electrons + 1/2 of bonding electrons)

Question 39

What are the 3 exceptions to the Octet rule?

Answer 39

Odd-Electron species Incomplete Octets Expanded Octets

Question 40

What is an Odd-Electron Species?

Answer 40

odd number of electrons, can't satisfy all octets - free radicals -unstable -few in number (e.g. NO)

Question 41

What are Incomplete Octets?

Answer 41

Where due to bonding preferences, octets are not full (e.g. BF3 as Boron likes to have only 3 bonds)

Question 42

What are Expanded Octets?

Answer 42

Where central atom has greater number of electrons than an octet can only occur in third row and beyond as they can access d orbitals

Question 43

What is Bond Energy?

Answer 43

Energy required to break one mole of the bond in the gas phase

Question 44

What is the relationship between bond length and energy?

Answer 44

in general as length increases, the bond gets weaker, trend doesn't always apply for similar compounds/ different compounds