The document discusses the group 1 elements known as the alkali metals (lithium, sodium, potassium, rubidium, cesium, and francium). It describes their physical and chemical properties, including their low melting points, softness, and reactivity with air and water. It also discusses the industrial extraction and important commercial uses of several alkali metals and their compounds, such as in batteries, fertilizers, soaps, and other products. The solubility and hydration of alkali metal salts is influenced by factors like the ions' charge densities.

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THE GROUP 1 ELEMENTS:
THE ALKALI METALS
“Read in the name your God who created “ Inorganic Chemistry 3

2. Jurusan Kimia
Chemistry Department
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3. Jurusan Kimia
Chemistry Department
Intro
• alkali metal cations are extremely difficult to reduce
 metal
• Davy (British) electrolyzed KOH(l) to extract the
first of the alkali metals.
• Perey (French), isolated the one alkali metal that
exists only as radioactive isotopes, francium
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Chemistry Department
All of the alkali metals :
- shiny, silver-colored metals.
- high electrical and thermal conductivities.
But, they are also very atypical :
Ex: the alkali metals are very soft, and they become softer
as one progresses down the group :
Thus, Li can be cut with a knife, whereas
K can be “squashed” like soft butter.
Group Trends

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Chemistry Department
Low m.p
High thermal conductivity and low m.p of Na
 heat transfer material in nuclear reactors
Low mp and soft is due to :
- Weak metalic bonding
- Small enthalpy of atomization
For “typical” metals, ∆Hatomization = 400 - 600
kJ/mol

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Chemistry Department
Low mp and soft is due to :
- Weak metalic bonding
- Small enthalpy of atomization
(for “typical” metals, ∆Hatomization = 400 -
600 kJ/mol)
( most metals ‘ densities = 5 – 15 g/cm3)
½ water density!
No!
reactive with
water

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Chemistry Department
exposed to air  a thick coating of oxidation
products covers the lustrous surface very rapidly :
-react with most nonmetals :
Must be stored under oil
white smoke
- dramatic reaction with water  supermetals

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Chemistry Department
Feature of alkali metal compounds
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Stabilization of Large Anions
Cations of the alkali metals (except Li+) :
the largest sizes  lowest charge densities,
 stabilize large low-charge anions.
All are metals  have common features.
Ions’ ox.nu = +1,
compounds : stable, ionic solids, colorless (without colored anion CrO4-, MnO4-)

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Chemistry Department
Ion Hydration
All ions are hydrated when dissolved in water.
However, this is not always true in the solid phase.
Hydration in the crystalline solid  balance of lattice energy (U) and
∆Hhydration of ions
U = electrostatic attraction between the cations and anions:
ion c.d ↑  U ↑.
U favors the loss of an ion’s hydration sphere on crystallization to give the
small (U ↑) anhydrous ion.
But ∆Hhydration depends on the attraction between the ion and the
surrounding polar water molecules.
A major factor contributing to the strength of the ion-dipole attraction is the
charge density of the ions.
In this ionic tug-of-war, we find that high charge density usually favors
retention of all or part of the hydration sphere in the
solid phase, while salts of low-charge ions tend to be anhydrous.

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Chemistry Department
Ion Hydration
Low charge densities (compared to other metals).
 majority of solid alkali metal salts are anhydrous !
c.D of Li+ & Na+ are high enough to
form of a few hidrated salts : LiOH.8H2O.
The lowest c.d of all metals,
very few K, Rb and Cs salts are hydrated
The low c.d are reflected in
the trend in ∆Hhidration among
the alkali metals
Mg2+ = 1920 kJ/mol

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Chemistry Department
Flame Colors characteristic flame color of alkali metal salt in a flame.

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Chemistry Department
1. ΔH ( U and ∆Hhydration of the cation and anion)
2. ΔS
Solubility of alkali metal salts
soluble, ΔG0 < 0
Where, ΔG0=ΔH0 - TΔS0
so useful as reagents in the laboratory of the required anions.
Solubility 
Fact,
why ?

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Chemistry Department
Solubility 
1. ΔH (the lattice energy and the enthalpy of hydration of the cation and anion)
2. ΔS
soluble, ΔG0 < 0
Where, ΔG0=ΔH0 - TΔS0

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Chemistry Department
The lattice energy
and hydration
enthalpy terms are
essentially equal.

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Chemistry Department
Amazing...

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Chemistry Department
very different in sizes more soluble
Although there is a strong dependence of
lattice energy on ionic charge, there is a
secondary relationship to the cation/anion
radius ratio; mismatch in ionic sizes will lead
to a lower than expected lattice energy.
Solubility vs M+  a smooth curve.

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Chemistry Department
Lithium
• the least dense metal (0.53 g.cmˉᶟ )
• bright silvery, but turning black if exposed to moist air :
• react with dinitrogen
(due to the greatest Li charge density of the group)
• Li (l) is the most corrosive material known
• the most negative Eo of any element 
releases more energy than any other element when it is oxidized.
Li⁺ (aq) + e⁻ → Li(s) E⁰ = -3.05
density (g•cm-3):
Lithium = 0.53
Al = 67,5
Iron = 7.874 g·cm−3
Iridium = 22.65

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Chemistry Department
Uses of Lithium
- Aerospace alloy
Density of alloy LA 141
(14%Li,1%Al, 85%Mg)=1.35 g/cm3 (=1/2 Aldensity )
- lithium greases-in automotive greases.
lithium stearate, C₁₇H₃₅COOLi,
(Water resistant, not harden at cold, stable at high T ).
• Extensive organometallic chemistry of Li
density (g•cm-3):
Lithium = 0.53
Al = 67,5
Iron = 7.874
Iridium = 22.65
Mobil

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Chemistry Department
Lithium batteries
As anode material:
 Eo >>>
 Low density (1/20 of Pb) 
mass saving.
 very low mass per unit of
stored energy  compact high-
voltage cells.
Lead acid battery :

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Chemistry Department
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Lithium-ion Batteries

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Chemistry Department
Sodium
1. Extraction of other metal (Th, Zr, tantalum and Ti.
ex : TiCl₄(l) + 4Na(s) → Ti(s) + 4 NaCl(s)
2. The production of the gasoline additive
tetraethyllead (TEL).
4NaPb(s) + 2C₂H₅Cl(g) → (C₂H₅)₄Pb(l) + 3 Pb(s) + 4NaCl(s)
• Uses Of Sodium
alloy

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Chemistry Department
The Industrial Extraction of Sodium

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Chemistry Department
Potassium
• K in the environment is a bit
radioactive (0.012% isotop K-40
radioactive).
 human body radiation
• K-40 / Ar-40 is one way of dating
rocks

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Chemistry Department
Insoluble Potassium Compounds
The least soluble : the greatest similarity in ion size.
 very large anion would form the least soluble salts with the large
cations of group 1.
The salts of very large [Co(NO₂)₆]ᶟˉwith :
Li and Na : soluble,
K, Rb, Cs : insoluble.
Test of Na+ or K+ in solution :
yellow

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Chemistry Department
The industrial Extraction of Potassium
• Electrolysis would be hazardous because of the extreme
reactivity of the metal.
• So, chemical process: (at 850⁰C) :
Na(l) + KCl(l) K(g) + NaCl(l)
Le Châtelier to get more K gas

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Chemistry Department
OXIDES
• Of the alkali metals, only Li forms a normal oxide :
4Li(S) + O₂(g) → 2Li₂O(s)
• Na₂O₂ (sodium peroxide),
containing the dioxide (2-) ion, O₂²⁻ (=peroxide ion)
2Na(s) + O₂(g) → Na₂O₂(s)
• The other three alkali metals react with an excess of O2 to form
dioxides(1-) (traditionally named superoxides) :

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Chemistry Department
HYDROXIDES
The solid hydroxide are white, translucent solids that absorb
moisture from the air until they dissolve in the excess water-a process
known as deliquescence.
Alkali metal hydroxides are all extremely hazardous because the
hydroxides ion reacts with skin protein to destroy the skin surface.

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Chemistry Department
The Industrial Synthesis of Sodium Hydroxide
electrolysis of brine (aqueous sodium chloride).
2H₂O(l) + 2e⁻ → H₂(g) + 2OH⁻(aq)
2Cl⁻(aq) → Cl₂(g) + 2e⁻
The diaphragm cell

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Chemistry Department
Commercial Uses of Sodium Hydroxide
1. Reagent in organic chemical plants,
2. Synthesis of other inorganic chemical.
3. pulp and paper industry,
4. 30 percent is used in hundreds of other ways.

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Chemistry Department
SODIUM CHLORIDE
Seawater is NaCl 3% solution,  table salts by using the
Sun’s energy to evaporate seawater
Salt was one of the earliest commodities to be traded

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Chemistry Department
Potassium chloride
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KCl is recovered from ancient
dried lake deposits,
the deposits also contain NaCl,
KMgCl3.6H2O; MgSO4.H2O; and
many other salts.

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Chemistry Department
differences in solubility
adding the mixture of crystals to saturated brine
electrostatic process
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Separation The Components

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Chemistry Department
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potassium chloride is
used as fertilizer.
Potassium ion is essential element for
plant growth and about 4.5 x 107
tonnes of potassium chloride are used
worldwide for this purpose every year,
so it is a major chemical product.

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Chemistry Department
Sodium Carbonate
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In North America, sodium carbonate is obtained
from the mineral trona, Na2CO3.NaHCO3.2H2O
(sodiumsesquicarbonate). Sesqui means “one and
one-half,” and it is the number of sodium ions per
carbonate unit in the mineral.
In the monohydrate process of
extraction, trona is mined about
400 m underground, crushed, and
then heated (calcined) in rotary
kilns.
Sodium carbonate is made by the Solvay,
or ammonia-soda, process. This process
involves the reaction of sodium chloride
with calcium carbonate:

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Chemistry Department
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- used in glass manufacture.
the sodium carbonate is reacted
with silicon dioxide (sand) and
other components at about 1500°C.
- used to remove alkaline earth metal
ions from water supplies
by converting them to their
insoluble carbonates, a process
called water “softening.”
Uses of Sodium Carbonate

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Chemistry Department
Sodium Hydrogen Carbonate
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Sodium hydrogen carbonate is less water-soluble than
sodium carbonate.
Thus, it can be prepared by bubbling carbon dioxide
through a saturated solution of the carbonate:
Heating sodium hydrogen
carbonate causes it to
decompose back to sodium
carbonate:

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Chemistry Department
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The main use is in the food industry (baking powder) ,
to cause bakery products to rise.

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Chemistry Department
Ammonia Reaction
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The alkali metals themselves have the unusual
property of dissolving in liquid ammonia to
yield solutions that are deep blue when dilute
When concentrated by evaporation, the solutions have a
bronze color and behave like a liquid metal. presence of a
transition metal catalyst, the solutions decompose to yield
the amide salt, NaNH2, and hydrogen gas:

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Chemistry Department
Ammonium Ion as
Pseudo-Alkali-Metal Ion
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A polyatomic ion whose behavior in many ways mimics that of an
ion of an element or of a group of elements.
ammonium ion is a polyatomic cation containing two nonmetals, it
behaves in many respects like an alkali metal ion.
The ammonium ion resembles an alkali metal ion in its precipitation
reactions.

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Chemistry Department
Biological Aspect
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The alkali metal ions
-balance the negative charge associated
with many of the protein units in the
body.
-help to maintain the osmotic pressure
within cells, preventing them from
collapsing.

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Chemistry Department
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The potential difference underlies many basic processes,
- the heart’s generation of rhythmic electrical signals
- the kidney’s unceasing separation of vital and toxic solutes in the blood,
- the eye’s precise control of the lens’s refractive index.
Cells pump sodium ions out of the
cytoplasm and pump potassium ions in. It is
this difference in total alkali metal ion
concentrations inside and outside cells that
produces an electrical potential across the
cell membrane.

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Chemistry Department
Element
Reaction
flowcharts
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