Ch 9; Covalent Bonds

Question 1

Vocab: VSPER model

Answer 1

A model based on an arrangement that minimizes the repulsion of unshared pairs of electrons

Question 2

Vocab: Exothermic

Answer 2

A chemical reaction in which more energy is released than is required to break bonds in the initial reaction

Question 3

Vocab: Molecule

Answer 3

Forms when 2 or more atoms covalently bond

Question 4

Vocab: Covalent bond

Answer 4

A bond that results from the sharing of valence electrons

Question 5

Vocab: Pi bond

Answer 5

A bond that is formed when parallel p-orbitals overlap to share electrons

Question 6

Vocab: Lewis structure

Answer 6

A model that uses electron dot structures to show how electrons are arranged in molecules

Question 7

Vocab: Sigma bond

Answer 7

A single covalent bond that is formed when an electron pair is shared by the direct overlap of bonding orbitals

Question 8

Vocab: Endothermic

Answer 8

A chemical reaction in which a greater amount of energy is required to break the existing bonds in the reactants than is released when the new bonds form in the product of molecules

Question 9

Vocab: Resonance

Answer 9

Condition that occurs when more than 1 lewis structure exists for the same molecule

Question 10

Vocab: Hybridization

Answer 10

The process by which the valence electrons of an atom are rearranged to form 4 new, identical hybrid orbitals

Question 11

Steps for naming covalent bonds:

Answer 11

1) name the first element ( never use prefixes such as mono & never change end to -ide)
2) Use theprefixes to indicate # of atoms in formula
3) Name second element & change end to -ide if neccessary
4) Use prefixes to indicate # of atoms in formula

Question 12

Steps for writing formulas for covalent compounds

Answer 12

1) Write symbol for the first element
2) Write subscript for element using any prefixes
3) Write symbol for second element
4) Write the subscript of the element using any prefixes
5) DO NOT REDUCE

Question 13

Diatomic molecules

Answer 13

Molecules with 2 atoms of the same element

Question 14

Richards Rule of 7’s

Answer 14

special diatomice molecules that naturally come in pairs

Question 15

Common covalent compounds

Answer 15

H2O = water
NH3 = ammonia
CH4 = methane
C3H8 = propane
C4H10 = butane
C8H18 = octane
C2H5OH = Ethanol

Question 16

Octet Rule

Answer 16

Atoms gain/lose/share electrons in order to obtain a full octet

Question 17

Covalent bond:

Answer 17

Def: chemical bond resulting in the sharing of valence electrons
Non-metal with a non-metal bond

Question 18

Bonding pair:

Answer 18

Pair of electrons shared, that belong to 2 atoms simulaneously

Question 19

Sigma bond

Answer 19

First covalent bond in a double or triple bond

Question 20

Unshared pairs

Answer 20

pair of valence electrons that do not participate in bonding

Question 21

Properties of Covalent compounds

Answer 21

insulators, insoluable in water, low melting point, low boiling point, soft, molecules seperate easily

Question 22

Properties of NETWORK covalent compounds

Answer 22

High melting point, high boiling point, electrical insulators, hard, insoluable in water

Question 23

Bond Dissociation Energy (BDE)

Answer 23

Amount of energy required to break a specific covalent bond

Question 24

Coordinate covalent bonds

Answer 24

When one atom contributes both bonding elevtrons to a single covalent bond

Question 25

Lewis Structure steps

Answer 25

1) add the valence electrons for each atom in the chemical formula
2) Draw a skeleton structure using the first element in the formula
3) subtract 2 electrons per bond in the skeletron structure
4) Distribute the remaining electrons with four in total for each element (including the bonds)
5) is everyone happy?
6) If it is polyatomic (has an exponent) then place brackets
7) does it have resonance?

Question 26

What happens when I run out of electrons?

Answer 26

Resonance: more than one valid lewis structure can be formed

Question 27

Exeptions to the octet rule

Answer 27

Elements 1-5
Hydrogen (bonds once, Duet rule)
Helium (duet rule)
Litium (duet)
Beryllium (bonds twice)
Boron (bonds 3 times)

Question 28

Hydrogen Bonding

Answer 28

“the boss” of intermolecular bonding, bonding of a covalently bonded hydrogen atom with an unshared electron pair

Question 29

Why hydrogen?

Answer 29

Because its nuculeus is electron deficient when it bonds with an electromagnatie atom

Question 30

Polarity of Molecules (steps)

Answer 30

1) draw the lewis structure
2) find the species type using the lewis structure
3) Find symmetry with VSEPR chart
Asymmetrical = polar covalant = no on the VSEPR chart