Part K: What are covalent Compounds?

31

Covalent compounds have widely varying properties.

The plastic casing of a ballpoint pen, the components of gasoline, the strongly scented components in a banana, and the carbon dioxide that we exhale with every breath are all covalent compounds.

Here are some properties that covalent compounds do share:

1. Covalent compounds have _____________________________________________.

Although the forces that hold atoms together in moleculesare very strong, the bonds that attract one molecule to another in a covalent compound are relatively __________________.

Therefore, when you __________ or ___________________ a covalent compound there is less

of a barrier to overcome so they will melt ___________________________________________.

Part L: Properties of Covalent Compounds

2. Covalent compounds are relatively _____________________.

The ___________________ of the forces between molecules also explains the relativesoftness of covalent compounds.

3. Covalent compounds are poor ____________________________.

Unlike ionic compounds, covalent compounds do not have free ____________________or ions. This covalent compounds poor conductors of both heat and electricity.

Properties of Ionic Compounds Properties of Covalent Compounds

32

Introduction Chemical compounds are combinations of atoms held together by chemical bonds. We have studied two basic types of compounds: ionic and covalent. Ionic compounds result when one or more electrons from one atom or group of atoms are transferred to another atom or group of atoms. In covalent compounds the electrons are shared by the bonded atoms.

The curls and waves of your hair are the result of many ionic, covalent and hydrogen bonds between the chains of atoms that make up each protein filament. Styling hair by wetting it or heating it with a curling iron is an attempt to change the hydrogen and ionic bonds. The solution in a “permanent” (or “perm”) on the other hand, breaks and reforms covalent bonds. A permanent wave does not wash out when you shampoo your hair.

The physical properties of a substance such as melting point and solubility tell us a lot about the type of bond in a compound. In this experiment, you will conduct tests on physical properties and compile data to enable you to classify compounds as ionic or covalent. You will also be given a unknown compound to test and predict whether it is an ionic or covalent compound.

Objective:

Materials

A - sodium chloride aluminum plates x 5

B - sucrose (C12H22O11) hot plate

C - potassium chloride 5 test tubes

D - acetaminophen (C8H9NO2) tongs

E - unknown sharpie

water

Lab: Comparing Properties of Ionic

and Covalent Compounds

33

Procedure

Part 1: Melting Point

1. Put on your safety glasses and keep them on until you have finished cleaning up yourlab station.

2. Label your aluminum trays A, B, C, D, E.3. Place a very SMALL sample of each substance A, B, C, D, E on the matching aluminum

tray.4. Plug in your hot plate and turn it on medium/high.5. Place two of the aluminum trays on the hot plate. Observe the substances in each tray

and make note of which substances melt.6. If the substance does not melt right away continue to observe for 4 minutes.7. Using the tongs, remove aluminum trays from the hot plate and continue the procedure

with your next two samples.

Part 2: Solubility

1. Place one SMALL scoop of each substance A, B, C, D, E into a separate clean testtube.

2. Fill the test tube ⅓ full with water and gently agitate the test tube for 3 minutes.3. Record your observations. Repeat this procedure for each of the test tubes.

Data

Substance Colour Melting Point: Does it melt?

Solubility: Does it dissolve?

Ionic or Covalent

A - sodium chloride chemical formula: ________

B - sucrose (C12H22O11)

C - potassium chloride chemical formula: ________

D - acetaminophen (C8H9NO2)

E - unknown

34

Analysis

1. Look carefully at your results. Do you see any patterns? Summarize the results fromyour experimental data on the last page based on whether you were observing an ionicor covalent compound. If you don’t see any patterns, state “no pattern”. If you do seegeneral patterns, state them.

Ionic Covalent

Melting Point

Solubility

2. Based on your experimental data and your analysis above, do you think the unknowncompound was ionic or covalent? Why?

3. Can you think of another property we could test to determine if an unknown substance is anionic compound or a covalent compound? Have a look at your notes for both types ofcompounds if you can’t think of anything.

35

NO

N-M

ET

ALS

ME

TA

LS

Ion

char

ge(s

)

47.9

Tita

nium

3+T

i4+

22

Ato

mic

Mas

sN

ame

Sym

bol

Ato

mic

Num

ber

PE

RIO

DIC

TA

BL

E O

F T

HE

EL

EM

EN

TS

Alk

alin

eE

arth

Met

als

Alk

ali

Met

als

Nob

leG

ases

Hal

ogen

s

Bas

ed o

n m

ass

of C

-12

at 1

2.00

.

Any

val

ue in

par

enth

eses

is th

e m

ass

of th

e m

ost

stab

le o

r be

st k

now

n is

otop

e fo

rel

emen

ts w

hich

do

not o

ccur

nat

ural

ly.

(262

)

Law

renc

ium

Lr

3+10

3

(259

)

Nob

eliu

m

3+N

o2+

102

(258

)

Men

dele

vium3+

Md

2+10

1

(257

)

Ferm

ium

Fm

3+10

0

(252

)

Eins

tein

ium

Es

3+99

(251

)

Cal

iforn

ium

Cf

3+98

(247

)

Berk

eliu

m4+B

k3+

97

(247

)

Cur

ium

Cm

3+96

(243

)

Amer

icium

Am

95

6+5+4+3+

5+3+6+4+

(244

)

Plut

onium

Pu

94

6+4+3+5+

(237

)

Nep

tuniu

m

Np

93

5+4+6+

238.

0

Ura

nium

U92

231.

0

Prot

actin

ium4+

Pa

5+91

232.

0

Thor

ium

Th

4+90

175.

0

Lute

tium

Lu

3+71

173.

0

Ytte

rbiu

m

2+Y

b3+

70

168.

9

Thul

ium

2+T

m3+

69

167.

3

Erbi

um

Er

3+68

164.

9

Hol

miu

m

Ho

3+67

162.

5

Dys

pros

ium

Dy

3+66

158.

9

erbi

umT

4+T

b3+

65

157.

3

Gad

olin

ium

Gd

3+64

152.

0

Euro

pium

2+E

u3+

63

150.

4

Sam

ariu

m4+S

m3+

62

(145

)

Prom

ethi

um

Pm

3+61

144.

2

Neo

dym

ium

Nd

3+60

140.

9

Pras

eody

miu

m

4+P

r3+

59

140.

1

Cer

ium

4+C

e3+

58

(266

)

Mei

tner

ium

Mt

109

(265

)

Has

sium

Hs

108

(262

)

Bohr

ium

Bh

107

(263

)

Sg

Seab

orgi

um

106

(262

)

Dub

nium

Db

105

(26

1)

Rut

herfo

rdiu

m

Rf

10

4

(22

7)

Act

iniu

m

Ac

3+

89

(226

)

Rad

ium

Ra

2+88

(223

)

Fran

cium

Fr

+87

(222

)

Rad

on

Rn

086

(210

)

Asta

tine

At

–85

(209

)

Polo

nium

4+P

o2+

84

020

9.

Bism

uth

5+B

i3+

83

207.

2

Lead

4+P

b2+

82

204.

4

Thal

lium

3+T

l1+

81

200.

6

Mer

cury

1+H

g2+

80

197.

0

Gol

d

1+A

u3+

79

195.

1

Plat

inum

2+P

t4+

78

192.

2

Iridi

um

4+Ir

3+77

190.

2

Osm

ium

4+O

s3+

76

186.

2

Rhe

nium

7+R

e4+

75

183.

8

ungs

ten

TW6+

74

180.

9

anta

lum

TTa5+

73

178.

5

Haf

nium

Hf

4+72

138.

9

Lant

hanu

m

La

3+57

137.

3

Bariu

m

Ba

2+56

132.

9

Ces

ium

Cs

+55

131.

3

Xeno

n

Xe

054

126.

9

Iodi

ne

I–

53

127.

6

Tellu

rium

Te2–

52

121.

8

Antim

ony5+

Sb

3+51

118.

7

Tin

2+S

n4+

50

114.

8

Indi

um

In3+

49

112.

4

Cad

miu

m

Cd

2+48

107.

9

Silv

er

Ag

+47

106.

4

Palla

dium

4+P

d2+

46

102.

9

Rho

dium

4+R

h3+

45

101.

1

Rut

heni

um

4+R

u3+

44

(98)

Tech

netiu

m

Tc

7+43

95.9

Mol

ybde

num3+

Mo

2+42

92.9

Nio

bium

5+N

b3+

41

91.2

Zirc

oniu

m

Zr

4+40

88.9

Yttri

um

Y3+

39

87.6

Stro

ntiu

m

Sr

2+38

85.5

Rub

idiu

m

Rb

+37

83.8

Kryp

ton

Kr

036

79.9

Brom

ine

Br

–35

79.0

Sele

nium

Se

2–34

74.9

Arse

nic

As

3–33

72.6

Ger

man

ium

Ge

4+32

69.7

Gal

lium

Ga

3+31

65.4

ZincZn

2+30

63.5

Cop

per

1+C

u2+

29

58.7

Nic

kel

3+N

i2+

28

58.9

Cob

alt

3+C

o2+

27

55.8

Iron

2+F

e3+

26

54.9

Man

gane

se

Mn

25

4+3+2+

52.0

Chr

omiu

m2+C

r3+

24

50.9

Vana

dium

4+V

5+23

47.9

Tita

nium

3+T

i4+

22

45.0

Scan

dium

Sc

3+21

40.1

Cal

cium

Ca

2+20

39.1

Pota

ssiu

m

K+

19

39.9

Argo

n

Ar

018

35.5

Chl

orin

e

Cl

–17

32.1

Sulfu

r

S2–

16

31.0

Phos

phor

us

P3–

15

28.1

Silic

on

Si

14

27.0

Alum

iniu

m

Al

3+13

24.3

Mag

nesi

um

Mg

2+12

23.0

Sodi

um

Na

+11

20.2

Neo

n

Ne

010

19.0

Fluo

rine

F9–

16.0

Oxy

gen

O–

82

14.0

Nitr

ogen

N–

73

12.0

Car

bon

C6

10.8

Boro

n

B5

9.0

Bery

llium

Be

+4

2

6.9

Lith

ium

Li

3+

4.0

Hel

ium

He

20

1.0

Hyd

roge

n

H1–

1.0

Hyd

roge

n

H1+

(294

)

Unu

noct

ium

Uu

o11

8

(?)

Unu

nsep

tium

Uu

s11

7

(292

)

Unu

nhex

ium

Uu

h11

6

(288

)

Uu

pU

nunp

entiu

m

115

(289

)

Unu

nqua

dium

Uu

q11

4

(28

4)

Unu

ntriu

m

Uu

t1

13

(28

5)

Unu

nbiu

m

Uu

b1

12

(272

)

Roe

ntge

nium

Rg

111

(281

)

Darm

stad

tium

Ds

110

12

34

56

78

910

1112

1314

1516

17

18

36

Positive Ions

NAMES, FORMULAE AND CHARGES OFSOME POLYATOMIC IONS

Negative Ions

NAMES AND FORMULAE OFCOMMON ACIDS

Hydrochloric acid

Sulfuric acid

Nitric acid

Acetic acid

NH4+ Ammonium CH3COO– Acetate

CO32– Carbonate

ClO3– Chlorate

ClO2– Chlorite

CrO42– Chromate

CN– Cyanide

Cr2O72– Dichromate

HCO3– Hydrogen carbonate, bicarbonate

HSO4– Hydrogen sulfate, bisulfate

HS– Hydrogen sulfide, bisulfide

HSO3– Hydrogen sulfite, bisulfite

OH– Hydroxide

ClO– Hypochlorite

NO3– Nitrate

NO2– Nitrite

ClO4– Perchlorate

MnO4– Permanganate

PO43– Phosphate

PO33– Phosphite

SO42– Sulfate

SO32– Sulfite

PREFIXES

1

2

3

4

5

6

7

8

9

10

mono

di

tri

tetra

penta

hexa

hepta

octa

nona

deca

HCl

H2SO4

HNO3

HCH3COO

37