S-Block Elements & Group 1 (Alkali Metals) – Key Vocabulary

Vocabulary flashcards summarizing essential terms, compounds, reactions, trends, and applications related to s-block elements—especially Group 1 alkali metals.

s-Block Elements

Elements in Groups 1 and 2 of the periodic table noted for low ionization energies and high reactivity.

Alkali Metals

Group 1 elements (Li, Na, K, Rb, Cs, Fr); soft, silvery-white, highly reactive metals.

Alkaline Earth Metals

Group 2 elements; reactive metals that form basic oxides and hydroxides.

Ionization Energy

Energy required to remove the outermost electron from an atom; very low in s-block elements.

Hydration Energy

Energy released when an ion is surrounded by water molecules; exceptionally high for Li⁺.

Atomic Radius

Distance from nucleus to outermost shell; increases down Group 1.

Polarizing Power

Ability of a small, highly charged cation (e.g., Li⁺) to distort nearby electron clouds.

Group 1 Elements

Lithium, sodium, potassium, rubidium, cesium, francium; collectively called alkali metals.

Lithium (Li)

Lightest alkali metal; shows anomalous properties such as high melting point and strong hydration.

Sodium (Na)

Abundant alkali metal used in salt, soap, glass, and paper production.

Potassium (K)

Alkali metal widely used in fertilizers, gunpowder, and certain electronic components.

Rubidium (Rb)

Rare alkali metal employed in atomic clocks, gas lasers, and PET imaging.

Cesium (Cs)

Heaviest stable alkali metal; key component of highly accurate atomic clocks and photoelectric cells.

Francium (Fr)

Radioactive Group 1 element with no significant commercial applications.

Diagonal Relationship

Similarity in properties between diagonally adjacent elements (e.g., Li with Mg or F), notable between Groups 1 and 7.

Anomalous Properties of Lithium

Set of traits (small size, high hydration, partial covalency, etc.) that make Li differ from other alkali metals.

High Hydration Energy

Large energy release when small ions like Li⁺ become solvated, enhancing their aqueous stability.

Low Density (Lithium)

Lithium’s density of 0.534 g cm⁻³, the lowest among metals, due to its small atomic mass and size.

Alkali Metal Reactivity

Tendency to lose one electron easily; increases down Group 1.

Feldspars

Common silicate minerals containing K, Na, or Li; major natural sources of Group 1 elements.

Micas

Sheet silicate minerals rich in K, Na, or Li; part of Group 1 element distribution.

Clay Minerals

Hydrated aluminosilicates that contain potassium, sodium, and lithium.

Evaporite Minerals

Deposits from seawater evaporation containing salts of Na, K, and Li.

Solvay Process

Industrial route to produce sodium carbonate from NaCl, NH₃, and CO₂.

Sodium Chloride (NaCl)

Table salt; extracted from seawater or mines; essential dietary mineral and preservative.

Sodium Hydroxide (NaOH)

Caustic soda; produced by brine electrolysis; used in soap, paper, and detergent manufacture.

Sodium Carbonate (Na₂CO₃)

Soda ash; made by the Solvay process; key ingredient in glass and detergents.

Sodium Bicarbonate (NaHCO₃)

Baking soda; mild alkali used in baking, cleaning, and as an antacid.

Table Salt

Common name for sodium chloride used in food seasoning and preservation.

Caustic Soda

Alternate name for sodium hydroxide, a strong base.

Soda Ash

Commercial term for sodium carbonate.

Baking Soda

Household name for sodium bicarbonate.

Water Softening

Process of removing Ca²⁺/Mg²⁺ using sodium compounds to prevent scale formation.

Lithium-ion Battery

Rechargeable battery technology that employs lithium as the anode material.

Atomic Clock

Time-keeping device using rubidium or cesium atom transitions for extreme precision.

Gas Laser

Laser using gases such as Rb or Cs to generate coherent light.

Photoelectric Cell

Device converting light to electricity; cesium is used for its low work function.

Hydrogen Gas

Flammable gas produced when alkali metals react with water.

Metal Hydroxide

Product (MOH) formed when Group 1 metals react with water, yielding alkaline solutions.

Metal Oxide

Compound (M₂O) formed when alkali metals burn in oxygen.

Atomic Radius Trend (Group 1)

Increases from Li to Cs due to addition of electron shells.

Ionization Energy Trend (Group 1)

Decreases down the group, making electron removal easier.

Melting Point Trend (Group 1)

Decreases from Li to Cs because metallic bonds weaken with larger atomic size.

Boiling Point Trend (Group 1)

Decreases down the group, paralleling the melting point trend.

Reactivity Trend (Group 1)

Increases down the group as outer electron becomes more loosely held.

Softness (s-Block Property)

Characteristic low hardness of Group 1 metals due to weak metallic bonding.

Luster (Shiny)

Bright, reflective surface typical of freshly cut s-block metals.

Electrical Conductivity (s-Block)

High ability of s-block metals to conduct electricity via free electrons.

Sodium-ion Battery

Emerging battery technology using sodium instead of lithium.

Potassium Fertilizer

Agricultural use of K compounds to enhance plant growth.

Lithium in Ceramics

Use of Li compounds to lower firing temperatures and improve thermal shock resistance.

Rubidium-82

Radioactive isotope used as a tracer in PET cardiac imaging.

Cesium-137

Radioactive isotope applied in SPECT imaging and industrial gauging.

Fuel Cell (Hydrogen)

Electrochemical cell generating electricity from H₂ and O₂; catalyst often Pt.

Rocket Propellant

Solid fuel mixtures containing lithium or beryllium for high energy density.

Complex Ion Formation (Li⁺)

Tendency of lithium to create stable coordination complexes due to high polarizing power.

Covalent Character of Li Compounds

Partial covalency in lithium salts arising from polarization of anions.

Oxide Formation Reaction

General equation: 4 M + O₂ → 2 M₂O (for Group 1 metals).

Hydroxide Formation Reaction

General equation: 2 M + 2 H₂O → 2 MOH + H₂ (vigorous reaction with water).

Basic Oxide

Metal oxide that reacts with water to yield a base; typical of Group 1 and 2 metals.

Basic Hydroxide

Strongly alkaline compound (e.g., NaOH) formed by s-block metals with water.