Chemical Bonding: Covalent Bonding Flashcards Preview

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Flashcards in Chemical Bonding: Covalent Bonding Deck (68):
1

what is covalent bonding?

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

2

when does covalent bonding occur?

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

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

3

do covalent bonds conduct electricity and why

no

Electrons are shared to complete the outer shell

they can’t move therefore doesn’t conduct electricity

4

how are covalent bonds represented?

with dot and cross diagrams 

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

5

what are the bonds between hydrogen atoms

very strong covalent bonds

6

what do molecules have?

a certain fixed number of particles

7

what are hydrogen molecules

diatomic

(contains two molecules)

H2

8

what is released when bonds are formed

energy

 makes things involved more stable

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

 

9

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

more stable

10

when hydrogen and chlorine bond together what molecule do they form

 a hydrogen chloride molecule 

11

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

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

12

what is the significance of noble gas structures

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

13

what is the symbol for a chlorine molecule

Cl2

14

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

a covalent bond

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

15

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

covalent bonds

16

what is the sybol and diagram for methane

symbol = CH4

the carbon atom has four unpaired electrons

they share one electron from four hydrogen atoms

 

17

what is they symbol and diagram for ammonia

the nitrogen atoms has three unpaired electrons

they share one electron from three hydrogen atoms

symbol =  NH3

18

what is the symbol and diagram for water?

symbol = H2​O

there are two unpaired electrons on the oxygen atom

they bond with two hydrogen atomssymbol = H2O

19

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

ethane

there is a carbon-carbon bond also

20

what is the symbol and diagram for ethane?

symbol = C2H6

21

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

one

22

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

two

23

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

three

24

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

double

25

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

triple

26

what is special about the structure of sodium hydroxide?

what is its diagram?

 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

27

what two types of structures are there in covalent bonding?

giant covalent

simple molecular

28

what type of bonding is simple molecular 

covalent

29

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

gases and liquids

30

how many atoms are bonded together in simple molecular structures

 2 or 3 atoms bonded together

(simple molecules)

31

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

attracted to each other through intermolecular force

this is a weak attractive force between two or more molecules

32

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

low

33

do simple molecular substances conduct electricity and why

do not conduct electricity

molecules don’t have any overall electrical charge

there are no electrons that can move from molecule to molecule

34

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

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

35

are simple molecular substances often organic solvents or not and why

yes

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

36

in water, how do you break the intermolecular forces?

by heating

37

does iodine crystal form a simple molecular structure or a giant covalent lattice?

what does its formation look like?

simple molecular

38

does water form a simple molecular structure or a giant covalent lattice?

what does its formation look like?

simple molecular

39

what state of matter are giant covalent structures?

mainly solids

40

are there intermolecular forces in giant covalent structures? why?

no

 only strong covalent bonds which need lots of energy to break

(except graphite)

 

41

what are some common properties of giant covalent structures?

Very high melting points and boiling points 

Solid, crystalline, hard

Do not conduct electricity

42

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

43

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

giant covalent structure

44

what is diamonds relationship with carbon?

it is a pure form of carbon

45

what is the structure of diamond?

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

 

46

is diamond a molecule? why?

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

47

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

giant covalent

48

is graphite a form of carbon?

yes

49

what is the structure of graphite like

3-D lattice structure

has a layer structure

layers slide easily over each other

50

why is graphite soft with a slimy feel?

layers easily slide over each other

mixed with clay to make pencils

pure graphite is used as dry lubricant

51

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

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

52

why is graphite less dense than diamond?

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

53

why does graphite conduct electricity?

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

54

what are intermolecular forces

forces of attractions between separate molecules

55

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

much weaker

they vary in strength from substance to substance

56

how do intermolecular forces work?

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

57

what will heating do to intermolecular forces?

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

58

what does melting do to intermolecular forces?

some but not all intermolecular forces are broken

 

59

what does boiling do to intermolecular forces?

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

60

do melting or boiling break the covalent bonds?

no

break intermolecular forces not the covalent bonds

61

where do intramolecular forces occur?

occurs in both simple molecular and giant covalent bonds

inside the molecules, attraction between atoms

62

what is the diagram for F2

63

what is the diagram for H2S

64

what is the diagram for CH4

65

what is the diagram for PH3

66

what is the diagram for SiCl4

67

what is the diagram for C2H6

68

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

check this