Ch 6 - Covalent Bonding

Question 1

what is covalent bonding?

Answer 1

attraction between the shared pair of negative electrons and the positive nuclei either side of it

Question 2

when does covalent bonding occur?

Answer 2

occurs between two non-metals (groups 4,5,6,7)

occurs in solids, liquids and gases (at room temperature)

Question 3

do covalent bonds conduct electricity and why

Answer 3

no

Electrons are shared to complete the outer shell

they can’t move therefore doesn’t conduct electricity

Question 4

how are covalent bonds represented?

Answer 4

with dot and cross diagrams

usually only draw outside shells but unless this is specified it is safer to draw all the shells

Question 6

what are the bonds between hydrogen atoms

Answer 6

very strong covalent bonds

Question 7

what are hydrogen molecules

Answer 7

diatomic

(contains two molecules)

H₂

Question 8

what do molecules have?

Answer 8

a certain fixed number of particles

Question 10

what is released when bonds are formed

Answer 10

energy

makes things involved more stable

the more bonds and atom can form, the more energy released, the more stable the bond becomes

Question 11

what type of bond is formed in a hydrogen chloride molecule and what is its diagram

Answer 11

covalent bond

Chlorine has one unpaired electron on outer shell

Hydrogen has one unpaired electron on outer shell

Both atoms bond together and form a covalent bond

Question 12

if hydrogen atom bonds with another hydrogen atom is it less or more stable

Answer 12

more stable

Question 13

when hydrogen and chlorine bond together what molecule do they form

Answer 13

a hydrogen chloride molecule

Question 14

what bond is formed in a chlorine molecule and what is its diagram

Answer 14

a covalent bond

each chlorine has an unpaired electron which is shared between the two chlorine atoms

Question 16

what is the sybol and diagram for methane

Answer 16

symbol = CH₄

the carbon atom has four unpaired electrons

they share one electron from four hydrogen atoms

Question 17

what is they symbol and diagram for ammonia

Answer 17

the nitrogen atoms has three unpaired electrons

they share one electron from three hydrogen atoms

symbol = NH₃

Question 18

what is the symbol and diagram for water?

Answer 18

symbol = H2​O

there are two unpaired electrons on the oxygen atom

they bond with two hydrogen atomssymbol = H₂O

Question 19

what is the significance of noble gas structures

Answer 19

ehen atoms bond covalently, they often produce outer electronic structures the same as noble gases

there are also lots of examples that look nothing like noble gas structures

Question 20

what is the symbol and diagram for ethane?

Answer 20

symbol = C₂H₆

Question 21

what is the symbol for a chlorine molecule

Answer 21

Cl₂

Question 23

what type of bond do each methane, ammonia and water form

Answer 23

covalent bonds

Question 24

what type of covalent bonding is formed in carbon dioxide and what is its diagram

Answer 24

double

Question 25

what type of covalent bonding in nitrogen and what is its diagram

Answer 25

triple

Question 26

what is special about the structure of sodium hydroxide?

what is its diagram?

Answer 26

you have Na (a metal) and OH (a non-metal) - this makes it ionic

however, the O and H are both non-metals and that makes it covalent

Question 30

what bonding is similar to that of methane and what is different?

Answer 30

ethane

there is a carbon-carbon bond also

Question 32

how many electrons are shared by each atom in single covalent bonding?

Answer 32

one

Question 33

how many electrons are shared by each atom in double covalent bonding?

Answer 33

two

Question 34

how many electrons are shared by each atoms in triple covalent bonding?

Answer 34

three

Question 37

does iodine crystal form a simple molecular structure or a giant covalent lattice? what does its formation look like?

Answer 37

simple molecular

Question 38

does water form a simple molecular structure or a giant covalent lattice? what does its formation look like?

Answer 38

simple molecular

Question 40

what two types of structures are there in covalent bonding?

Answer 40

giant covalent simple molecular

Question 41

what type of bonding is simple molecular

Answer 41

covalent

Question 42

what does the giant covalent lattice of silicon dioxide (sand) SiO₂ look like?

Answer 42

Question 43

what state of matter do simple molecular substances tend to be?

Answer 43

gases and liquids

Question 44

how many atoms are bonded together in simple molecular structures

Answer 44

2 or 3 atoms bonded together | (simple molecules)

Question 45

what is the structure of diamond?

Answer 45

each carbon atom has four unpaired electrons on its outer shell each carbon atoms bonds strongly to four other carbon atoms and each carbon forms four covalent bonds tetrahedral arrangement which continues on and on in three dimensions

Question 46

how are the atoms in simple molecular substances attracted to each other

Answer 46

attracted to each other through intermolecular force this is a weak attractive force between two or more molecules

Question 47

do simple molecular substances have high or low melting and boiling points

Answer 47

low

Question 48

do simple molecular substances conduct electricity and why

Answer 48

do not conduct electricity molecules don’t have any overall electrical charge there are no electrons that can move from molecule to molecule

Question 49

what is the structure of graphite like

Answer 49

3-D lattice structure has a layer structure layers slide easily over each other

Question 50

do simple molecular substances tend to be soluble or insoluble in water and why?

Answer 50

insoluble (unless they react with it) due to their size, water molecules have stronger intermolecular attractions between them than you might think attractions need to be broken for a substance to dissolve so that the dissolving molecules can fit between them any new attractions between water molecules and the covalent molecules are not usually big enough to make up for this

Question 51

are simple molecular substances often organic solvents or not and why

Answer 51

yes intermolecular attractions between the two different types of molecule are much the same as in the pure substances

Question 52

in water, how do you break the intermolecular forces?

Answer 52

by heating

Question 53

why does graphite conduct electricity?

Answer 53

each carbon atom is only joined to three others one electron drops between the layers and becomes delocalised this electron is free to move around the layer

Question 56

what state of matter are giant covalent structures?

Answer 56

mainly solids

Question 57

are there intermolecular forces in giant covalent structures? why?

Answer 57

no only strong covalent bonds which need lots of energy to break (except graphite)

Question 58

what are some common properties of giant covalent structures?

Answer 58

Very high melting points and boiling points Solid, crystalline, hard Do not conduct electricity

Question 60

does diamond form a simple molecular structure or a giant covalent structure?

Answer 60

giant covalent structure

Question 61

what is diamonds relationship with carbon?

Answer 61

it is a pure form of carbon

Question 62

what is the diagram for F₂

Answer 62

Question 63

what is the diagram for H₂S

Answer 63

Question 64

what is the diagram for CH₄

Answer 64

Question 65

what is the diagram for PH₃

Answer 65

Question 66

what is the diagram for SiCl₄

Answer 66

Question 67

what is the diagram for C₂H6

Answer 67

Question 69

is diamond a molecule? why?

Answer 69

not a molecule because atoms joined up in a real diamond is completely variable (depends on size of crystal) molecules always contain a fixed number of atoms joined by covalent bonds

Question 70

is graphite a giant covalent structure or a simple molecular structure?

Answer 70

giant covalent

Question 71

is graphite a form of carbon?

Answer 71

yes

Question 73

why is graphite soft with a slimy feel?

Answer 73

layers easily slide over each other mixed with clay to make pencils pure graphite is used as dry lubricant

Question 74

why does graphite have a high melting point, boiling point and is soluble in any solvents

Answer 74

to melt or dissolve graphite you need to break the whole structure, including the covalent bonds, not just the layers very large amounts of energy needed as bonds are very strong

Question 75

why is graphite less dense than diamond?

Answer 75

the layers in graphite are relatively far apart distance between graphite layers is more than twice the distance between atoms in each layer graphite cyrstal contains a lot of water space, whereas there is none in a diamond crystal

Question 77

what are intermolecular forces

Answer 77

forces of attractions between separate molecules

Question 78

are intermolecular bonds are weaker/stronger than ionic or covalent bonds

Answer 78

much weaker they vary in strength from substance to substance

Question 79

how do intermolecular forces work?

Answer 79

the slightly positive end of one molecule attracts the slightly negative end of a neighbouring molecule

Question 80

what will heating do to intermolecular forces?

Answer 80

will supply energy to break these intermolecular attractions causes the substance to either melt or boil doesn’t take much heat energy to break intermolecular attractions

Question 81

what does melting do to intermolecular forces?

Answer 81

some but not all intermolecular forces are broken

Question 82

what does boiling do to intermolecular forces?

Answer 82

the attractions are completely disrupted and the molecules become free to move around as a gas

Question 83

do melting or boiling break the covalent bonds?

Answer 83

no break intermolecular forces not the covalent bonds

Question 84

where do intramolecular forces occur?

Answer 84

occurs in both simple molecular and giant covalent bonds inside the molecules, attraction between atoms

Question 91

what is the difference between simple molecular substances and giant covelant structures?

Answer 91

check this