GROUP 1: ALKALI METALS

Alkali Metals Overview

Also known as: Lithium family

Group Members: Hydrogen (H), Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs), Francium (Fr)

Common Properties: Single valence electron, form +1 ions, incredibly reactive with water

Note: Hydrogen is often placed in Group 1 due to its electron configuration, though it has unique properties and is not considered an alkali metal

H

Hydrogen

Unique
Atomic Number 1
Atomic Mass 1.008 u
Electron Config 1s¹
Common Ions H⁺, H⁻
Melting Point -259.1°C
Density 0.0000899 g/cm³
Hydrogen is the most abundant element in the universe, making up about 75% of all normal matter and fueling stars through nuclear fusion!

Properties: Colorless, odorless gas, lightest element, highly flammable

Applications: Fuel cells, rocket fuel, ammonia production, hydrogenation of oils, welding

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Li

Lithium

Reactive
Atomic Number 3
Atomic Mass 6.94 u
Electron Config [He] 2s¹
Common Ions Li⁺
Melting Point 180.5°C
Density 0.534 g/cm³
Lithium is the only metal that floats on water and is less dense than most oils!

Properties: Lightest metal, soft, silvery-white, reactive

Applications: Batteries, ceramics, glass, mood stabilizers, alloys

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Na

Sodium

Very Reactive
Atomic Number 11
Atomic Mass 22.99 u
Electron Config [Ne] 3s¹
Common Ions Na⁺
Melting Point 97.8°C
Density 0.97 g/cm³
Sodium is the 6th most abundant element in Earth's crust and essential for nerve function and fluid balance in all animals!

Properties: Soft, silvery-white, highly reactive, essential for life

Applications: Table salt, street lights, cooling nuclear reactors, soap production

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K

Potassium

Explosive
Atomic Number 19
Atomic Mass 39.10 u
Electron Config [Ar] 4s¹
Common Ions K⁺
Melting Point 63.4°C
Density 0.86 g/cm³
Potassium is so reactive it will ignite and burn with a beautiful violet flame when exposed to water!

Properties: Soft, silvery-white, very reactive, essential nutrient

Applications: Fertilizers, soaps, gunpowder, dietary supplements, nuclear reactors

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Rb

Rubidium

Pyrophoric
Atomic Number 37
Atomic Mass 85.47 u
Electron Config [Kr] 5s¹
Common Ions Rb⁺
Melting Point 39.3°C
Density 1.53 g/cm³
Rubidium can be liquid at room temperature and spontaneously ignites in air!

Properties: Soft, silvery-white, pyrophoric, very reactive

Applications: Atomic clocks, photocells, vacuum tubes, medical imaging

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Cs

Cesium

Most Reactive
Atomic Number 55
Atomic Mass 132.91 u
Electron Config [Xe] 6s¹
Common Ions Cs⁺
Melting Point 28.4°C
Density 1.93 g/cm³
Cesium is the most reactive metal and will explode violently on contact with water!

Properties: Soft, gold-colored, most reactive metal, pyrophoric

Applications: Atomic clocks, photoelectric cells, drilling fluids, cancer treatment

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Fr

Francium

Radioactive
Atomic Number 87
Atomic Mass 223 u
Electron Config [Rn] 7s¹
Common Ions Fr⁺
Half-life 22 minutes
Stability Extremely rare
Francium is so rare that there's probably less than 30 grams in the entire Earth's crust at any time!

Properties: Radioactive, extremely rare, most unstable alkali metal

Applications: Scientific research only

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