Anorganik Alkali Metal

8/18/2019 Anorganik Alkali Metal

1/17

INORGANIC CHEMISTRY II“CHEMISTRY OF ALKALINE

EARTH METAL”

BY:1. NI PUTU WULAN ROMIANINGSIH

(1113031073/I A!". NI PUTU ASRI WIN#AYANI

(111303107$/I A!3. PUTU CAN#RA YUNI ARTINI

(1113031077/I A!

CHEMISTRY E#UCATION #EPARTMENT

FACULTY OF MATHEMATICS AN# NATURAL SCIENCES

GANESHA UNI ERSITY OF E#UCATION

SINGARA%A

"013


2/17

No. IndicatorScore

(1-10)Weight

Score x

Weight1. Content

1.1 Title 11.2 Introduction: interesting, logic,

structure of writing, coherency and

unity.

1

1.3 Body: the concepts, quality of

explanation discussion!, coherency,

unity

"

1." Concluding #e$ar%: showing

conclusion or re$ar%ing future loo%s

or suggestion.

1

1.& #eferences: way to cite, way to

write and concise, enough rele'ant

reference.

1

2. (on)Content2.1 *nglish quality writing 1

2.2 +rder of typing, figure, ta le, andti$e of hand in.

1

T+T- 1/


3/17

CHEMISTRY O !"#!"INE E!RTH MET!"

0roup II- ele$ents in periodic ta le are %nown as the al%aline earth $etal.The al%aline earth $etals are so$ewhat less electropositi'e and less reacti'e than the

al%ali $etals Chang, 2/1/: /1!. *xcept for the first $e$ er of the fa$ily,

erylliu$, which rese$ les alu$inu$ a 0roup 3- $etal! in so$e respects, the

al%aline earth $etals ha'e si$ilar che$ical properties. The relationships a$ong the

ele$ents in group II- erylliu$, $agnesiu$, calciu$, strontiu$, ariu$ and

radiu$! are 'ery li%e those a$ong the al%ali $etals. Because their 2 ions attain the

sta le electron configuration of the preceding no le gas, the oxidation nu$ er of al%aline earth $etals in the co$ ined for$ is al$ost always 2. #adiu$ was little to

say in this essay ecause it is radioacti'e and is for$ed as 224 Ra 55 6)e$itter in the

235U 2 decay series. This essay will explain riefly the history, a undance, isolation,

uses and properties of al%aline earth $etal ele$ents, as well as the properties of

al%aline earth $etal co$pounds such as the hydrides, halides, oxides, hydroxides,

and salt of oxyacids.

The earliest %nown al%aline earth was li$e atin: calx!, which is now %nownto e calciu$ oxide7 it was used in ancient ti$es in the co$position of $ortar.

agnesia the na$e deri'es pro a ly fro$ the ancient district of agnesia in -sia

inor!, the oxide of $agnesiu$, was shown to e an al%aline earth different fro$

li$e y the 8cottish che$ist 9oseph Blac% in 1 &&7 he o ser'ed that $agnesia ga'e

rise to a solu le sulfate, whereas that deri'ed fro$ li$e was %nown to e insolu le.

In 1 " Carl ;ilhel$ 8cheele, the 8wedish che$ist who disco'ered oxygen, found

that the $ineral called hea'y spar or arys 0ree%: hea'y! contained a new earth,which eca$e %nown as aryta ariu$ oxide!. - further earth, strontia strontiu$

oxide!, was identified y the ondon che$ists -dair Crawford and ;illia$

Cruic%shan% in 1 / on exa$ining a $ineral strontiu$ car onate! found in a lead

$ine at 8trontian in -rgyllshire, 8cotland. Beryllia erylliu$ oxide! was extracted

fro$ the $ineral eryl and recogniauquelin in 1 5 Britannica *ncyclopedia, 2/12!.

1


4/17

agnesiu$, calciu$, strontiu$, and ariu$ that is ele$ents deri'ed fro$

al%aline earths were isolated as i$pure $etals y 8ir ?u$phry @a'y in 15/5 y

$eans of the electrolytic $ethod he had pre'iously used for isolating the al%ali$etals potassiu$ and sodiu$. The al%aline)earth $etals were later produced y

reduction of their salts with free al%ali $etals, and it was in this way the action of

potassiu$ on erylliu$ chloride! that erylliu$ was first isolated y the 0er$an

che$ist =riedrich ;Ahler and the =rench che$ist -ntoine Bussy independently in

1525. #adiu$ was disco'ered in 15 5 y $eans of its radioacti'ity y ierre and

arie Curie, who separated it fro$ ariu$ Britannica *ncyclopedia, 2/12!.

$ro%ertie&

The group 2 ele$ents are good conductor and electricity. The al%aline earth

$etals are less electropositi'e and less reacti'e than the al%ali $etals. In all

co$pounds, group 2 ha'e an oxidation nu$ er 2. The o ser'ed result of this

decrease in si


5/17

Source: (Chang, 2010: 901)

Berylliu$ and $agnesiu$ are grayish $etals, while the re$aining group 2

$etals are soft and sil'er)colored. The $etals are $allea le, ductile and quite rittle7

in air, the shiny surface of each $etal quic%ly tarnishes ?ousecroft 8harpe, 2//5:

3/&)3/4!.

The ele$ents in 0roup 2 II-!, with the exception of erylliu$, ha'e 'ery

si$ilar che$ical properties, with $uch of their che$istry go'erned y their tendency

to lose two electrons to achie'e a no le gas electron configuration. In general,

ele$ents in this group are good reducing agents. -lthough not as 'iolently reacti'e

toward water as the al%ali $etals, the al%aline earths react readily with acids to

generate hydrogen:

g 2? D g 2 ? 2

The reducing a ility of these ele$ents increases with ato$ic nu$ er. -s a

consequence, calciu$ and the hea'ier al%aline earths react directly with water in a

reaction that can con'eniently generate s$all quantities of hydrogen:

Ca ? 2+ D Ca +?! 2 ? 2

iessler Tarr, ):2&&!

;hen heated, all the group 2 $etals co$ ine with + 2, ( 2, sulfur or halogens as

shown in the following equation.

2 + 2 D 2 + E Ca, 8r, Ba

3 ( 2 D 3 ( 2

5 8 5 D 5 8

F 2 D F 2 F E =, Cl, Br, I

;hen heated with ? 2, Ca, 8r and Ba for$ saline hydrides, ? 2, ut g

reacts only under high pressure. In contrast, Be? 2 is prepared fro$ erylliu$ al%yl.

Berylliu$ co$ ines with car on at high te$perature to for$ Be 2C. The other

ele$ents of group 2 $etals for$ car ides C 2. ;hereas Be 2C reacts with water, the

car ides of the later $etals hydroly


6/17

C 2 2? 2+ D +?! 2 C 2? 2 E g, Ca, 8r, Ba

Berylliu$ is distinctly different fro$ the other al%aline earths in its che$ical

properties. The s$allest of the al%aline earths, it participates pri$arily in co'alentrather than ionic onding. -lthough the ion GBe ? 2+! "H2 is %nown, free Be 2 ions are

rarely, if e'er, encountered. Berylliu$ and its co$pounds are extre$ely toxic, and

special precautions are required in their handling. iessler Tarr, ):2&&!

Besides, e$ission spectra for the group 2 $etals are readily o ser'ed and

fla$e test can e used to distinguish etween Ca, 8r and Ba containing co$pounds:

Ca orange)red, ut pale green when 'iewed through lue gas!, 8r cri$son, ut

'iolet through lue gas!, Ba apple)green! ?ousecroft 8harpe, 2//5: 3/&)3/4!.

!6+ndance

Berylliu$ occur as the silicate $ineral beryl , Be 3-l 2G8i4+ 15H. It is also found

in $any natural $inerals, and precious for$s including emerald and aquamarine .

agnesiu$ and calciu$ are the eighth and fifth $ost a undant ele$ents in the

*arth s crust, and g is third $ost a undant in the sea. The ele$ents g, Ca, 8r and

Ba are widely distri uted in $ineral and as dissol'ed salts in seawater. The $inerals

are dolomite CaC+ 3. gC+ 3!, magnesite gC+ 3!, oli ine g,=e! 28i+ "!,

carnallite JCl. gCl 2.4? 2+!, CaC+ 3 chal!, limestone , and marble !, gy"sum

Ca8+ " .2? 2+!, calastite 8r8+ "!, strontianite 8rC+ 3! and barites Ba8+ "!. #adiu$

is radioacti'e and is for$ed as 224 Ra 55 in the235U 2 decay series. ?ousecroft

8harpe, 2//5: 3/&)3/4!

I&o ationagnesiu$ is produced in se'eral ways. Two i$portant sources are dolo$ite

roc% and seawater. agnesiu$ is $anufactured on a large scale. The $ixed $etals

car onate dolo$ite as ther$ally deco$posed to a $ixture of Ca+ and g+, g+ is

reduced y ferrosilicon in (i 'essels7 g is re$o'ed y distillation in acuo .

?ousecroft 8harpe, 2//5: 3/4!

2 g+ 2Ca+ =e8i D 2 g Ca 28i+ " =e T E 1"&/ J

"


7/17


8/17

#adiu$ as radioacti'e was first isolated y ierre and arie Curie fro$ the

uraniu$ ore, pitch lende. It was collected fro$ solutions y coprecipitation with

Ba8+ " and the nitrates su sequently fractionally crystalli


9/17

originally used in stage lightening #atcliff et. al, 2//": 215!. @ry sand and Ca+

$ixtures can e stored and transported. +n adding water, and as C+ 2 is a sor ed, the

$ortar sets as solid CaC+ 3. The sand in the $ortar is a inding agent.Ca+ s! ? 2+ l! D Ca +?! 2 s! N &r / E )4& %9 $ol )1

Ouic%li$e 8la%ed li$e

Ca +?! 2 s! C+ 2 g! D CaC+ 3 s! ? 2+ l!

?ousecroft 8harpe, 2//5: 3/ !

i$e is also used in the steel industry, pulp, and paper $anufacturing, and extraction

of g. =or exa$ple, calciu$ car onate is in $anufacturing of steel, glass, ce$ent

and concrete. arge quantities of Ca +?! 2 are used to $anufacture leaching powder, Ca +Cl! 2.Ca +?! 2.CaCl 2.2? 2+ and in water treat$ent. Calciu$ fluoride

that occurs in nature as the fluorspar is i$portant as the raw $aterial for the

$anufacture of ?= and = 2 as the following reaction equation.

Ca= 2 ? 28+ " D 2?= Ca ? 8+ "!2

In s$all a$ount, Ca= 2 is also used as a flux in the steel industry, for welding

electrode coatings, and $anufacture of glass.

There are two $ineral source of strontiu$, na$ely the sulfate celestite! and

car onate strontianite!. The $ain use of strontiu$ is as a co$ponent in color

tele'ision faceplate glass where it has function to stop F)ray e$issions fro$ the

cathode ray tu e C#T!. +ther uses of strontiu$ are in ferrite cera$ic $agnets and

pyrotechnics.

Barite Ba8+ "! which is %nown as the $ineral of ariu$ is used as weighting

$aterial in oil and gas. +n s$all scale of application, the a ility of Ba8+" to stop the

passage of F)rays leads to its use as a barium meal in radiology for i$aging the

ali$entary tract. Lses of Ba as a getter in 'acuu$ tu es arise fro$ its high reacti'ity

with gases including + 2 and ( 2. #adiu$ has een used in the treat$ent of cancerous

tu$ors, ut its use has largely een superseded y other radioisotopes.

H dride&

-ll 0roup II ele$ents, except erylliu$, for$ hydrides y direct co$ ination

with hydrogen. Berylliu$ hydride Be? 2! was first prepared in 1 &1 y reduction of


10/17

BeCl 2 in ether and y reaction of Be e 2 with i-l? " . The purer one can e o tained

y pryolysis of Be t)Bu! 2 at 21/ oC. 0reenwood *arnshaw7 1 : 11&!

The hydrides of the $etals except $agnesiu$ and erylliu$ are white andionic solids. The hydrides are sta le in dry air ut react with water, the 'igor of the

reaction increasing with the $olecular weight of the hydride.

? 2 2? 2+ D +?! 2 ? 2 P

This reaction is due to the 'ery strong asic property of the hydride ion ? ) which

eha'es as a powerful proton acceptor and is therefore strongly asic, i.e.

? ) ? 2+ D ? 2 +? )

;hen the $olten ionic hydrides are electroly


11/17

Be ato$ are dependents on the nature of the ridging group and are related to the

presence of lone pairs on the ridging ato$s.

Be

Cl

Cl

Be

Cl

Cl

Be

Cl

Cl

Be

'igure 1 he chain structure o$ *eCl 2

In the gas phase at high te$perature, the halides for$s are linear $olecules, F)Be)F.

-t low te$perature, howe'er, the halides exist in apprecia le a$ounts as di$er.

Be

Cl

Cl

Be

'igure 2 he dimer structure o$ *eCl 2

Cotton, 1 &: 3/5!

The lower $e$ ers in 0roup II for$ essentially ionic halides, with $agnesiu$

ha'ing inter$ediate properties. 8ince they are ionic7 therefore ha'e relati'ely high

$elting point, the $elts acting as conductors. The ro$ide, chloride, iodide readily

a sor water. The a ility to for$ hydrates as well as solu ility in water decrease with

increasing ato$ic si


12/17

industrially and its concentration in sea water exceed only y (aCl. Calciu$ chloride

CaCl2! also has great i$portance. Its traditional use include: 1! rine for

refrigeration plants7 2! control snow and ice on highways and pa'e$ents7 3! dustcontrol on secondary roads, unpa'ed streets. 0reenwood *arnshaw7 1 : 11 !

Oxide&

The oxides +! are white, high $elting crystalline solids, with (aCl)type

lattice. They are est o tained y calcining the car onates. Berylliu$ oxide Be+!

has good che$ical sta ility and a 'ery high conducti'ity. Calciu$ oxide Ca+!,

which is also referred to as quic%li$e, is one of the oldest $aterials %nown to$an%ind. Ouic%li$e is produced y the ther$al deco$position of calciu$ car onate:

CaC+ 3 s! Ca+ s! D C+ 2 g !

Calciu$ oxide is used in ce$ent, $ortar and plaster $anufacture. It still has a 'ery

i$portant role in purifying iron, as it reacts with i$purities in the ore to fro$ a

$olten slag:

Ca+ 8i+ 2 D Ca8i+ 3

#atcliff, et al., 2//": 21 !

The che$istry of $agnesiu$ is inter$ediate etween that of erylliu$ and the

hea'ier 0roup 2- ele$ents. agnesiu$ does not react with cold water ut does

react slowly with stea$:

g s! ? 2+ g ! D g+ s! ? 2 g !

agnesiu$ oxide reacts 'ery slowly with water to for$ $agnesiu$ hydroxide, a

white solid suspension called mil! o$ magnesia, which is used to treat acid

indigestion:

g+ s! ? 2+ l ! D g +?! 2 s!

Chang, 2/1/: /2!

H droxide&

The hydroxides W +?! 2 of al%aline earth $etal are generally less solu le and

are of lower ase strength than al%aline $etal Cha$ ers ?olliday, 1 &: 13/!.

Berylliu$ hydroxide is o tained as a white gelatinous precipitate when +? ) ions are

added to a solution of a erylliu$ salt. Berylliu$ hydroxide is a$photeric and this

1/


13/17

sets it apart fro$ the hydroxide of the other group 2 $etals which are asic. This

a$photeric is also shown y alu$iniu$ hydroxide in 0roup III where it has

characteristic of s$all ions of high charge, i.e. Be 2 and -1 3 ?ousecroft 8harpe,2//5: 31 !. It is only sparingly solu le in water, dissol'ing in strong acids to gi'e the

hydrated erylliu$ ion GBe ? 2+! "H2 , ut also dissol'ing in solutions containing the

hydroxide ion to gi'e the tetrahedral co$plex ion of tetrahydroxo eryllate II! ion

GBe +?! "H2 7 addition of acid first reprecipitates the hydroxide Be +?! 2 as a white

gelatinous hydrated precipitate! and then re)dissol'es it to gi'e the hydrated ion7

hence the following is sequence of the reaction Cha$ ers ?olliday, 1 &: 131!:

[Be(H 2 O) 4 ]2+

+?

H+

Be(OH) 2(H2 O) 2

+?

H+ [Be(H 2 O) 4 ]

2-

+?

Be

?+

+?

+?

2)

'igure etrahedral com"le- ion o$ .*e(/&) 2

The other 0roup II hydroxides W +?! 2 WE g, Ca, 8r, Ba! are sparingly

solu le in water, the solu ility increasing down the group7 as do their ther$al

sta ilities with respect to deco$position into + and ? 2+ ?ousecroft 8harpe,

2//5: 31 !. agnesiu$ hydroxide acts as wea% ase, whereas Ca +?! 2, 8r +?! 2 and

Ba +?! 2, are strong ase. agnesiu$ hydroxide is precipitated only y anapprecia le concentration of hydroxide ion not y a$$oniu$ hydroxide in presence

of a$$oniu$ chloride! and the others are not precipitated. agnesiu$ hydroxide is

a wea% al%ali and is also used in toothpastes7 where it helps to neutrali


14/17

Soda lime is a $ixture of (a+? and Ca +?! 2 and is $anufactured fro$ Ca+ and

aqueous (a+?. 8oda li$e is easier to handle than (a+? and is co$$ercially

a'aila le, eing used, for exa$ple, as an a sor ent for C+2, and in qualitati'e testfor G(? "H salts, a$ides, i$ides and related co$pounds which e'ol'e (? 3 when

heated with soda li$e.

Ta le 2. 8u$$ary roperties of ?ydroxide

E e/ent 'e Mg Ca Sr 'a

M(OH) 8

Insolu le 8olu ility increase

-$photeric Base strength increase

Source: (Chambers &olliday, 1934: 1+1)

Sa t& o* ox acid&

There are so$e salts of oxyacids of group two $etal such as the car onates

and sulfates. ost erylliu$ salts of strong oxyacids crystalli


15/17

Ca ?C+ 3!2 aq!⇌ CaC+ 3 s! C+ 2 g! ? 2+ l!

Ca ?C+ 3!2 aq! Ca +?! 2 aq! D 2CaC+ 3 s! ? 2+ l!

er$anent hardness is caused y other g 2 and Ca 2 salts e.g. sulfates!. The process of water softening in'ol'es passing the hard water through a cation)exchange

resin. ;ashing)$achine detergents contain M uilders that re$o'e g 2 and Ca 2 ions

fro$ washing water7 polyphosphate ha'e een used for this purpose, ut ecause

phosphates are da$aging to the en'iron$ent,


16/17

in high)speed aircraft and $issiles, and in co$$unication satellites7 $agnesiu$ is

still used in the $anufacture of firewor%s, flares, and photographic flashlights and

$edical applications such as indigestion powder mil! o$ magnesia , g +?! 2! and a purgati'e %"som salts , g8+ " . ? 2+!7 uses of calciu$ co$pounds far outnu$ er

those of the $etal, with the world production of Ca+, Ca +?! 2, Ca+. g+,

Ca +?! 2. g+ and Ca +?! 2. g +?! 2.7 strontiu$ is used as a co$ponent in color

tele'ision faceplate glass7 radiu$ has een used in the treat$ent of cancerous

tu$ors. -l%aline earth $etals are for$ing co$pounds with other ele$ents in the

for$ of hydrides, halides, oxides, hydroxides, and salt of oxyacids which ha'e

different characteristics.

1"


17/17

Re*erence&9

-l%aline *arth etals . 2/12. *ncyclopZdia Britannica. %ncyclo"5dia *ritannicaUltimate Re$erence Suite Chicago: *ncyclopZdia Britannica.

Cha$ ers, C.,?olliday, -.J.. 1 &. 6odern 7norganic Chemistry: #n 7ntermediate

e-t 0reat Britain: Butterworth Co td.

Chang, #ay$ond. 2/1/. Chemistry enth %dition . (ew [or%: c 0raw ?ill

Co$pany.

Cotton, =.-, ;il%inson, 0, and 0aus, . . 1 &. *asic 7norganic Chemistry: hird

%dition (ew [or%: 9ohn ;iley 8on0reenwood, ( (, *arnshaw, -. 1 . Chemistry o$ the %lements: Second %dition

0reat Britain: *lse'ier td.

?ousecroft, Catherine *., 8harpe, -lan 0.. 2//5. 7norganic Chemistry: hird

%dition Italia: #otolito a$ arda.

iessler , 0ary . and Tarr, @onald -. ). 7norganic Chemistry . Third *dition.

innesota: earson.

#atcliff, Brian et.al. 2//". Chemistry: #S 8e el and # 8e el . *ngland: Ca$ ridge

Lni'ersity ress.

1&

Documents

Anorganik Alkali Metal