Transcript
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Location on the periodic table.
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Physical Properties.
They are harder and denser than sodium andpotassium, and have higher melting points.
(this is due to the presence of two valent
electrons in the outermost shell of each atom,which results in stronger metallic bonding
than group 1)
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The atomic and ionic radius increases as you
go down the group. The ionic radii are much smaller than the
atomic radii.
(this is because the atom contains twoelectrons in its outermost shell, which areremoved to form the ion. So the remainingelectrons are closer to the nucleus, and the
increased nuclear charge attracts theelectrons closer to the nucleus, thusdecreasing the size of the ion.)
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Chemical Properties. Reactions with oxygen and chlorine are vigorous.
2Mg(s) + O2(g)
2MgO(s) Ca(s) + Cl2(g)
CaCl2(s) All the metals except beryllium form oxides in air.
Barium is so reactive, its stored in oil.
All the metals except beryllium reduce water and dilute acids
to hydrogen. Mg(s) + 2H+(aq)Mg(aq) + H2(g) Magnesium reacts slowly with water unless the water is
boiling, but calcium reacts rapidly even at room temperature,
and forms a cloudy white suspension ofsparingly soluble
calcium hydroxide. Calcium, strontium and barium reduce hydrogen gas when
heated, forming a hydride. Ca(s) + H2(g)CaH2(s)
The hot metals also reduce nitrogen gas and form nitrides
3Mg(s) + N2(g)Mg3N2(s)
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Magnesium can reduce, and burn in, carbon
dioxide: 2Mg(s) + CO2(g)2MgO(s) + C(s)
Calcium, strontium and barium oxides react
with water to form hydroxides
CaO(s) + H2O(l)Ca(OH)2(s)
(Calcium hydroxide is known as slaked lime. It is
sparingly soluble in water and the mildly alkaline
solution is known as lime water which is used to
test for the acidic gas carbon dioxide.)
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Be
Beryllium
MgMagnesium
Ca
Calcium
Sr
Strontium
Ba
Barium
Ra
Radium
Beryllium DOES NOT add color tothe flame upon burning.
The colour of the flame remains
the original one or has a whitishcolour as that of Magnesium.
Therefore Beryllium does not
have an accurate flame test colour.
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Be
Beryllium
MgMagnesium
Ca
Calcium
Sr
Strontium
Ba
Barium
Ra
Radium
Magnesium burns with asparkling white flame
This flame is very bright and can
be blinding
It is used in special Magnesium
lights.
2Mg + O2 = 2MgO
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Be
Beryllium
MgMagnesium
Ca
Calcium
Sr
Strontium
Ba
Barium
Ra
Radium
Calcium burns with a strongbrick-red
2Ca + O2 = 2CaO
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Be
Beryllium
MgMagnesium
Ca
Calcium
Sr
Strontium
Ba
Barium
Ra
Radium
Strontium burns with a red-crimson flame.
2Sr + O2 = 2SrO
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Be
Beryllium
MgMagnesium
Ca
Calcium
Sr
Strontium
Ba
Barium
Ra
Radium
Barium burns with a pale/apple
green. 2Ba + O2 = 2BaO
Fire cracker with Barium
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Be
Beryllium
MgMagnesium
Ca
Calcium
Sr
Strontium
Ba
Barium
Ra
Radium
Radium burns with a purple-redflame.
However it is a very violent
combustion, therefore a GeigerMuller tube is used.
The Geiger Muller tube or Geiger
counter detects the radiation toidentify the element.
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Sources
http://en.wikipedia.org/wiki/Flame_test
http://en.wikipedia.org/wiki/Alkaline_earth_
metal
http://webmineral.com/help/FlameTest.shtml
http://www.rsc.org/chemsoc/visualelements/
pages/data/intro_groupii_data.html
Videos from Youtube (Multiple Search Keys)
http://en.wikipedia.org/wiki/Flame_testhttp://en.wikipedia.org/wiki/Alkaline_earth_metalhttp://en.wikipedia.org/wiki/Alkaline_earth_metalhttp://webmineral.com/help/FlameTest.shtmlhttp://www.rsc.org/chemsoc/visualelements/pages/data/intro_groupii_data.htmlhttp://www.rsc.org/chemsoc/visualelements/pages/data/intro_groupii_data.htmlhttp://www.rsc.org/chemsoc/visualelements/pages/data/intro_groupii_data.htmlhttp://www.rsc.org/chemsoc/visualelements/pages/data/intro_groupii_data.htmlhttp://webmineral.com/help/FlameTest.shtmlhttp://en.wikipedia.org/wiki/Alkaline_earth_metalhttp://en.wikipedia.org/wiki/Alkaline_earth_metalhttp://en.wikipedia.org/wiki/Flame_test7/29/2019 Group II Elements - Alkaline Metals
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Be
Beryllium
MgMagnesium
Ca
Calcium
Sr
Strontium
Ba
Barium
Ra
Radium
Reactivity
Trend
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Be
Beryllium
MgMagnesium
Ca
Calcium
Sr
Strontium
Ba
Barium
Ra
Radium
Reactivity
Trend
I
N
C
R
EA
S
I
N
G
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Be
Beryllium
MgMagnesium
Ca
Calcium
Sr
Strontium
Ba
Barium
Ra
Radium
Reactivity
Trend
I
N
C
R
EA
S
I
N
G
Least Reactive
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Be
Beryllium
MgMagnesium
Ca
Calcium
Sr
Strontium
Ba
Barium
Ra
Radium
Reactivity
Trend
I
N
C
R
EA
S
I
N
G
Least Reactive
Most Reactive
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Magnesium Calcium Strontium Barium
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Sources
http://en.wikipedia.org/wiki/Alkaline_earth_metal
http://en.wikibooks.org/wiki/General_Chemistry/
Chemistries_of_Various_Elements/Group_2 http://www.chemguide.co.uk/inorganic/group2/r
eacth2o.html
http://wiki.answers.com/Q/What_is_the_trend_
of_reactivity_of_group_2_elements
Videos from Youtube (Multiple Search Keys)
http://en.wikipedia.org/wiki/Alkaline_earth_metalhttp://en.wikipedia.org/wiki/Alkaline_earth_metalhttp://en.wikibooks.org/wiki/General_Chemistry/Chemistries_of_Various_Elements/Group_2http://en.wikibooks.org/wiki/General_Chemistry/Chemistries_of_Various_Elements/Group_2http://www.chemguide.co.uk/inorganic/group2/reacth2o.htmlhttp://www.chemguide.co.uk/inorganic/group2/reacth2o.htmlhttp://wiki.answers.com/Q/What_is_the_trend_of_reactivity_of_group_2_elementshttp://wiki.answers.com/Q/What_is_the_trend_of_reactivity_of_group_2_elementshttp://wiki.answers.com/Q/What_is_the_trend_of_reactivity_of_group_2_elementshttp://wiki.answers.com/Q/What_is_the_trend_of_reactivity_of_group_2_elementshttp://www.chemguide.co.uk/inorganic/group2/reacth2o.htmlhttp://www.chemguide.co.uk/inorganic/group2/reacth2o.htmlhttp://en.wikibooks.org/wiki/General_Chemistry/Chemistries_of_Various_Elements/Group_2http://en.wikibooks.org/wiki/General_Chemistry/Chemistries_of_Various_Elements/Group_2http://en.wikipedia.org/wiki/Alkaline_earth_metalhttp://en.wikipedia.org/wiki/Alkaline_earth_metal7/29/2019 Group II Elements - Alkaline Metals
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Beryllium
It is used in small amounts to make copper
beryllium alloy that are very strong and hard.
These alloys are used to make hand tools to
be used in environment where sparking isconsidered a fire hazard. It is also used in
making small precision bearings. Alloys of
nickel and beryllium are used for makingcomponents that need to withstand very high
temperatures.
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Magnesium
Magnesium is an element important for all
living beings, as a constituent of chlorophyll
responsible for photo-synthesis in plants.
Magnesium, being light and strong metal, itsalloy with aluminum and zinc finds many uses
in construction and in manufacture of
airplane.
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Calcium
It is an important nutrient for us forming a majorpercentage of our bones and teeth. Its compoundssuch as limestone and gypsum are used as buildingmaterials since ancient times, and continue to be used
today also directly or as raw material for making otherconstruction material. Marble used as decorative stonein construction is also a compound of calcium. Lime isused for in many industrial processes such as steel
refining, paper making, food, cosmetic,pharmaceutical, toothpaste, chewing gum, andvitamins. It is also used for treating industrial waste.
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Strontium
Compounds are widely used in fireworks and
flares for the red color they produce when
burnt. Strontium carbonate is used as a glass
additive. Strontium hydroxide is used forrefining beet sugar.
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Barium
Barium sulfate, in well-drilling operations as a
lubricating mud. A form of barium sulfate
called barium meal is used in medical field to
examine functioning of digestive process ofpatients through X-ray.
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Organic Chemistry
The alkaline earth metals are known to form
organometallic compunds.Of these,
organomagnesium compounds, usually in the
form of Grignard reagents are widely used inOrganic Chemistry. Other important
compounds formed are Organoberyllium,
Organocalcium, Organostrontium,Organobarium and Organoradium.
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Limestone Cycle
Limestone Starts off as Calcium Carbonate , when heated thecalcium carbonate becomes Calcium Oxide (this is also known assolid Quicklime) + Carbon Dioxide, the Calcium Oxide then reactswith water to produce Calcium Hydroxide and then when morewater is added then filtered it becomes Calcium Hydroxide Solution,C02 is then added to form Calcium Carbonate again.
1. Calcium Carbonate ---> Calcium Oxide(s) + Carbon Dioxide(g).CaCO3(s) + heat --->CaO(s) + CO2(g).
2. Calcium Oxide(s) + Water(l) ---> Calcium Hydroxide(s)2CaO(s) + H2O(l) ---> 2Ca(OH)2(s).
3. Calcium Hydroxide(aq) + Carbon Dioxide (g) ---> CalciumCarbonate(s) + Water (l)
2Ca(OH)2(aq) + 2CO2(g) ---> 2CaCO3(s) (suspension) + 2H2O(l)
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The Limestone Cycle
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Q1. In the olden days, the photographers flash
bulb gave out a shot of sparkling bright- white
light to light up the subject. What Group 2aelement could have possibly been used in the
bulb?
a. Barium
b. Calcium
c. Magnesiumd. Strontium
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Q2. A boy lights up a firecracker made with
metals from Group 2a of the periodic table.
The firecracker bursts with white and greensparks. What elements could the firecracker
contain?
a. Magnesium and Strontium
b. Strontium and Calcium
c. Magnesium and Calcium
d. Barium and Magnesium
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Q3. Select the correct order of reactivity.(Increasing)
a. Barium, Magnesium, Calcium, Strontium,Beryllium, Radium
b. Beryllium, Magnesium, Calcium, Strontium,
Barium, Radium
c. Magnesium, Beryllium, Calcium, Strontium,Barium, Radium
d. Radium, Barium, Strontium, Calcium,Magnesium, Beryllium
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Q4. This element combines with other metals to
form an alloy which is used to make tools to
be used in an environment where sparking isconsidered a fire hazard. What Group 2A
element is this?
a. Beryllium
b. Barium
c. Calciumd. Strontium
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Q4 D t i h th T F l
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Q4. Determine whether True or False:
1. Limestone Starts off as Calcium Carbonate
2. Calcium Carbonate is also known asQuicklime
3. Beryllium and Magnesium can both formoxides in air
a. True, False, True
b. True, False, False
c. True, True, False
d. False, Flase, True
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