S BLOCK Flashcards
1st Grp. elements(Alkali Metals)
lithium , sodium , potassium, rubidium, caesium and francium
2nd Grp. elements(Alkaline earth metals)
beryllium, magnesium, calcium, strontium, barium, radium
Half life time of francium
21 minutes(longest lived isotope) and radioactive
where are alkaline earth metals found
earth crust as meta oxides
where do calcium and magnesium rank in abundance
where is radium found
igneous rocks
E.C of alkali metals
[noble gas] ns1
E.C of alkaline earth metals
[noble gas] ns2
which 2 pairs are in diagonal relationship
lithium and magnesium ; beryllium and aluminium
diagonal relationship arises due to
similar ionic sizes or charge/mass ratio
elements present in bio fluids to maintain ion balance and treat nerve disorders
sodium, potassium, calcium and magnesium
ion formed by first grp. elements
M+ (most electropositive)
which grp. elements are most electropositive
1st
which grp. elements have largest sizes
1st
general value of I.E for 1st grp. elements
low
trend of atomic radius in grp.1
increases top t bottom
trend of I.E in grp.1
decreases down the grp.(incr. size outweighs the nuclear charge)
trend of hydration enthalpies in grp. 1
decreases top to bottom
physical appearance of grp.1 elements
silvery white , soft and light
general value of density in grp.1
low
trend of density with exception
increases down the group but potassium lighter than sodium
general value of M.P and B.P of grp.1
low due to weak metallic bonding
Photoelectric color of li
crimson red
Photoelectric color of na
yellow
Photoelectric color of k
violet
Photoelectric color of rb
red violet
Photoelectric color of cs
blue
how can alkali metals be detected
flame tests
elements used as electrodes in grp.1
caesium and potassium
reactivity of alkali metals
high due to large size and low I.e
alkali metals + air
burn vigorously in oxygen to tarnish by producing oxides
monoxide is formed by which alkali metal
lithium
peroxide is formed by which alkali metal
sodium
oxides formed by k,rb,cs
superoxide
O.S of alakli metals
+1
li+n
li3n is formed by li exceptional reactivity
where are alkali metals stored due to high reactivity towards water
kerosene
alkali metals+ water
hydroxide with h2
which alkali metal has the most e- value
lithium
which alkali metal has the least e- value
sodium
which alkali metal is an exception to their explosive reaction to water
lithium due to very low size
alkali metals+h2 9673k)
hydrides (M+H-)
alkali metals with halogens
ionic halides (M+X-)
which is the only alkali metal that forms a covalent halide
lithium
which lithium halide is most covalent
lithium iodide
nature if alkali metals in redox rxns.
reducing agents
most powerful r.a alkali metal
lithium due to high hydration enthaly
least powerful r.a alkali metal
sodium
relation between standard reduction potential and r.a
inversely proportional
alkali metals + liq. nh3 solns.
alkali metals dissolve and turn it into blue color due to ammoniated e-
magnetic nature of alkali metal + ammonia soln.
paramagnetic
ammoniated e-+M+
amide + h2
in conc. ammonia soln. blue color and paramagnetic changes to
bronze color and diamagnetic
use of li
with mg to make armor plates
with al to make aircraft parts
with pb to make bearings for motor engines
thermonuclear rxns.
electrochemical cells
use of na
with na to make anti knock additives to petrol
liq. coolant in nuclear rxns.
use of potassium
bio fluid
fertilizer
soft soap(KOH)
absorbent of CO
use of cs
devising photoelectric cells
li+air
li2o mostly and some li2o2
na+air
na2o2 mostly and some nao2
trend if stability of oxides
increases with incr. in metal ion sizes
alkali metal oxides+water
hydroxides
color of oxides and peroxides
colorless
color of super oxides
yellow and orange
magnetic nature of superoxides
paramagnetic
widely used alkali metal oxide as o.a
sodium peroxide
alkali metal hydroxides appearance
white crystalline solids
most strong bases
alkali metal hydroxides
physical nature alkali metal halides
high MP and colorless crystalline solids
HX+ appropriate oxide/hydroxide/carbonate
alkali metal halides
trend of formation enthalpy of alkali metal halides
high negative down the grp. except fluorine
trend of formation of alkali metal halides
less negative from MF to MI
trend of MP of halides
decreases don the grp.
solubility of alkali metal halides in water
high except LiF(very low) and CsI(very high)
licl is soluble in which organic compound
pyridine
carbonates of metal oxo acids
metal bicarbonates most likely and metal carbonates too
nature of alklai metal oxo acids
thermally stable soluble i water
alkali metals + oxo acids
salts
trend of stability of alakli metal carbonates
increases down the grp.
which alkali metal carbonate is unstable to heating
li
reasons for anamolous behaviour of li
very small size
high polarizing power which gives rise to high covalent characters
anamolous properties of li
hardest
high MP and BP
;east reactive but strongest r.a
mainly forms li2o and li3n with air
deliquescent
crystallizes as hydrates
lithium HCs aren’t available as solids
doesn’t form ethynide with ethyne
lithium nitrate(li3n) heated to give li2o but generally nitrites are formed
lif and li2o are comparitively less water soluble
reason for diagonal relationship with mg
similar sizes
diagonal similarities between li and mg
harder and lighter
slow rxn. with water
less stable and soluble oxides and hydroxides
nitrates
nitrates heated to give oxides instead of nitrogen
oxides don’t give superoxides
carbonates are decomposed easily on heating to from oxides and co2
halides are soluble in ethane
halides are deliquescent and crystallize to form aq. solns. as hydrates
industrial name of sodium carbonate(na2co3.10h20)
washing soda
washing soda is prepared by what process
solvay orocess
advantage of sodium hydrogen carbonate that promotes it to undergo solvay process
less solubility
by product of solvay process
calcium chloride
reactants of solvay process
ammonium carbonate, nacl, co2
appearance of washing soda
white crystalline solid
solubility in water
readily soluble
type of hydrate formed on heating washing soda
monohydrate
monohydrate of washing soda above 373 K
white powder called soda ash
carbonate prt of washing soda + h2o
alkaline soln.
uses of washing soda
softening, laundering, cleaning
manufacture of glass, borax, soap, caustic soda
paper, paint and textile industry
lab reagent in qualitative and quantitative analysis
most abundant source of nacl
sea water
how is salt produced in india
evaporating sea water
salt produced in india every year
50 lakh tons
impurities in brine
caso4, na2so4, cacl2, mgcl2
reactants in prep. of nacl
crude nacl, water, hcl (gas)
use of nacl
table or common salt
prep of na2o, naoh, na2co3
industrial name of naoh
caustic soda
process of prep. of caustic soda
elctrolysis
reactants used in the prep of naoh
brine soln., mercury cathode, carbon anode
what is produced at cathode in naoh prep.
sodium amalgam(nahg)
what is obtained at anode in naoh prep.
cl2 gas
from which initial product do we get naoh
sodium amalgam
appearance of naoh
white, translucent solid, deliquescent
MP of naoh
591K
MP of nacl
1081K
nature of naoh
strongly alkaline
naoh+co2
na2co3
uses of naoh
manufacture of soap paper, artifical silk
petroleum refining
purification of bauxite
mercerising cotton
prep. of pure fats and oil
lab reagent
industrial name of sodium hydrogen carbonate(nahco3)
baking soda
use of sodium bicarbonate
mild antiseptic for skin infections
fire extinguishers
reactants used in prep. of baking soda
na2co3, h2o, co2
most abundant metal in our body
potassium
where are na cells found inside our body
outside the cells in interstitial fluids like blood plasma
use of na in our body
messengers
transport sugar and amino acids
controls flow of water across cell membrane
use of potaasium in our body
enzyme activator
oxidizes glucose
mesenger
pump that operates across cell membranes
na-k pump
energy consumed by na-k pump
1/3rd ATP in resting animal
15Kg in a day in resting human
relation between size of grp. 2 and grp.1 elements
grp.2 < grp.1 due to incr. in nuclear charge
trend of atomic radius in grp.2
incr. down the grp.
general value of IE in grp.2 elements
low
trend of IE in grp.2
decreases down the gr.
relation between IE1 of grp. 2 and grp.1 elements
grp.1 < grp. 2
relation between IE2 of grp. 2 and grp.1 elements
grp.1 > grp. 2
trend of hydration enthalpies in grp. 2
decreases down the grp.
relation between hydration enthalpies of grp. 2 and grp.1 elements
grp. 2 > grp.1
appearance of alkaline earth metals
slivery white, lustrous and relatively soft but harder than alkali metals
relation between MP and BP of grp. 2 and grp.1 elements
grp. 2 > grp. 1
trend of electropositive character in grp.2 elements
incr. down the grp.
calcium color to flame
brick red
strontium color to flame
crimson
barium color to flame
apple green
alkaline earth metals that don’t release color on de excitation
be and mg
flame test for which alkaline earth metals is helpful in qualitative and quantitative estimation
ca, sr, ba
alkaline earth metals conductivity vaue generally
high
reactivity of alkaline earth metals
less than alkali metals
alkaline earth metals which are chemically inert to water due to formation of oxide film
be and mg
be and mg when burnt in air
mo and m3n2
ca, ba, strontium + air
oxide, nitride and also hydroxides
alkaline earth metals + x2
MX2
convenient way to make bef2
thermal decomposition of (nh4)2bef4
becl2 is prep. from
beo
alkaline earth metals + h2
metal hydrides
condition for formation of beh2
becl2+lialh4
alkaline earth metals + acids
h2 is liberated
nature of grp. 2 elements in redox rxns.
r.a
grp. 2 element with least r.a tendency
beryllium
relation between reducing power of grp.1 and grp. 2
grp.1 > grp.2
alkaline earth metals + liq. nh3 solns.
deep blue black solns. with ammoniated ions
uses of be
cu-be alloys in high strength springs
windows of x ray tubes
uses of mg
mg-al alloy in aircraft making
flash powders, bulbs, incedinary bombs
milk of magnesia as antacids
mgco3 as toothpastes
uses of ca
extradition of metals from oxides
which 2 alkaline earth metals are combined used for removing air from vaccum
ca and ba
use of radium
radiotherapy like to treat cancer
O>S of grp.2 elements
2
nature of grp.2 elements compounds
ionic but less than alkali metals
nature of beo and mgo
covalent
structure of alkaline earth metals oxide and hydroxide
rock salt except beo
nature of alkaline earth metal oxides
ionic and basic except beo (covalent and amphoteric)
trend of solubility , stability and basic character of A.E.Ms
incr. down the grp. but less than alkali metals
nature of A.E.M halides
ionic except beo(covalent)
structure of beo
chain which forms chloro-bridged dimer that dissociates into linear one at high temperatures
Trend of Halide formation in grp.2
decreases down the grp.
way to dehydrate grp.2 elements
heat them(except be and mg - hydrolysis on heating)
stability between grp.2 fluorides and chlorides
f < cl
Water solubility of grp. 2 carbonates
insoluble
Trend of Water solubility of grp. 2 carbonates
decreases down the grp.
where only can beo be kept
atmosphere of co2
Trend of Thermal stability in grp.2
incr. down the grp.
Trend of Water solubility of grp. 2 sulphates
decr. down the grp.
Appearance of grp. 2 sulphates
white solids
Water of crystallization of mg3n2 and be3n2
6 and 0
grp. 2 nitrates on decomposition give
oxides
anamolous properties of be
largely covalent
easily hydrolysed
maximum CN=4
oxide and hydroxide are amphoteric
reason for anamolous properties of be
very small size
reason for diagonal relationship between be and al
same size and similar charge to mass ratio
diagonal similarities between be and al
not readily attacked by acids
dissolve in water to give beryllate and aluminate ion
chlorides are ridged in vapor phase and strong L.A
string tendency to form complexes
calcium oxide is also called as
quick lime(CaO)
prep. of cao
limestone heating
appearance of cao
white amorphous solid
MP of cao
2870K
addition of limited amount of water to break lump of cao is called
slaking of lime
quick lime slaked with soda lime gies
solid sodalime
uses of cao
manufacturing cement, na2co3 from naoh and dye stuffs
purification of sugar
cheapest from of alkali
cao
ca(oh)2 is also known as
slaked lime(CaCO3)
prep. of slaked lime
cao=water
appearance of slaked lime
white amorphous powder
Water solubility of slaked lime
very less
aq. slaked lime is called
lime water
slaked lime in water is called
milk of lime
co2 + saked lime
milky due to caco3 formation
caco3+h2o
calcium bicarbonate
milk of lime + cl2
hypochlorite (a bleaching powder constituent)
uses of ca(oh)2
prep. of mortar
white wash
disinfectant
tanning industry
prep. of bleaching powder and glass
purification of water
caco3 exists in nature as
limestone, marble
prep. of caco3
slaked lime + co2
(or)
na2co3 + cacl2
appearance of caco3
white fluffy powder
Solubility of caco3 in water
insoluble
caco3 decomposes on heating to from
cao + cp2
caco3 + dilute acid
liberates co2
uses of caco3
manufacture of cao
building material
marble
along with mgco3 used in metal extraction
manufacture of high quality
paper
antacid
toothpaste
contituent of chewing gum
filler in cosmetics
calcium sulphate is also called
plaster of paris (pop) (caso4.1/2 h2o)
pop is decrystallized at and to
above 393 K to caso4 (dead burnt plaster)
time taken to form plastic plate with pop in water
5 - 15 minutes
uses of pop
building industry
setting up fractures and sprains
dentistry
ornamental works
getting casts and moulds
cement was introduced by
Joseph Aspidin(1824)
what was the other name of first introduced salt
Portland cement
composition of cement
cao - 50 to 60 %
sio2 - 20 to 25%
al2o3 - 5 to 10%
mgo - 2 to 3%
so3- 1 to 2%
ratio of silica and alumina for good cement
2.5:4
ratio of lime to silicon, aluminium, iron oxides
2
raw material for cement
limestone and clay
prep. of cement
limestone and clay - cement clinker + 2 to 3% gypsum(caso4.2 h2o)
important ingredients of portland cement
dicalcium silicate and tricalcium silicate and aluminate
hydration of molecules of constituents and their rearrangement to give hard mass of cement
setting of cement
what is added to slow down the process of setting of cement
gypsum
uses of cement
concrete manufacture and reinforcement
plastering
construction of bridges, dams
amount of grp.2 elements in our body
mg - 25g
Ca - 1200g
uses of mg and ca in our body
mg acts as cofactor to enzymes that utilize atp
chlorophyll has mg
99% body ca is in bones and teeth
ca is neuromuscular messenger
ca concentration in blood plasma is around 100 mg/L maintained by 2 hormones calcitonin and parathyroid
