alkali_metal_powerpoint
Overview of the Periodic Table
Groups of Elements
Elements in the periodic table are classified into various groups:
Group I: Alkali Metals
Group II: Alkaline Earth Metals
Group III: Poor Metals
Group IV: Carbon Group
Group V: Nitrogen Group
Group VI: Chalcogens (Oxygen Group)
Group VII: Halogens
Group VIII: Noble Gases
Group I: Alkali Metals
Characteristics:
All alkali metals are solids at room temperature, except for Francium (Fr), known
for being highly radioactive.
They easily lose a single electron to form +1 ions, achieving a stable electron
configuration.
Reactivity is observed to increase as one progresses down the group.
Electron Configuration:
Lithium (Li): [He] 2s¹
Sodium (Na): [Ne] 3s¹
Potassium (K): [Ar] 4s¹
Common Properties of Alkali Metals
Electron Structures:
Lithium: 2,1
Sodium: 2,8,1
Potassium: 2,8,8,1
Reactivity Trends:
There is an increase in reactivity as one moves down the group due to larger
atomic size and the shielding effect.
Electronegativity:
Alkali metals possess low electronegativity values which increase down the
group.
Physical Properties:
Alkali metals appear shiny when cut, conduct heat and electricity well, are
relatively soft, and have low density.
They are softer and less dense than transition metals.
Flame Colors:
Sodium produces a yellow flame, lithium a red flame, and potassium a lilac flame.
Density Trends:
Density generally rises as one moves down the group, although potassium is
less dense than sodium.
Lithium, sodium, and potassium are all less dense than water, allowing them to
float.
Reaction Characteristics
Melting Points:
Melting points decline as one descends the group, requiring less energy to lose
the outer electron due to increasing atomic radius.
Reaction with Air:
All alkali metals react with air to form metal oxides, which leads to tarnishing,
increasing down the group.
Examples:
Lithium: 4Li + O2 -> 2Li2O
Sodium: 4Na + O2 -> 2Na2O
Reaction with Water:
They react vigorously with water, with reactivity escalating down the group,
producing alkaline hydroxides and hydrogen gas.
Reactions:
Lithium: 2Li + 2H2O -> 2LiOH + H2 (moves slowly across water)
Sodium: 2Na + 2H2O -> 2NaOH + H2 (fizzes and may ignite)
Potassium: 2K + 2H2O -> 2KOH + H2 (burns with lilac flame)
Reaction with Chlorine:
Alkali metals react rapidly and violently with chlorine gas to form metal chlorides.
Example: Lithium: 2Li + Cl2 -> 2LiCl
Uses of Alkali Metals
Lithium:
Utilized in medical treatments for bipolar disorder, lithium-ion batteries, and
CO2 absorption systems for spacecraft.
Sodium:
An essential component in table salt, used in street lighting (especially sodium
vapor lamps), and plays a role in cooling processes for nuclear reactors.
Potassium:
Widely used in fertilizers essential for plant growth and is also employed in
producing explosives.