The alkali metals

The alkali metals, found in group 1 of the periodic table (formerly known as group IA), are very reactive metals that do not occur freely in nature. These metals have only one electron in their outer shell. Therefore, they are ready to lose that one electron in ionic bonding with other elements. As with all metals, the alkali metals are malleable, ductile, and are good conductors of heat and electricity. The alkali metals are softer than most other metals. Cesium and francium are the most reactive elements in this group. Alkali metals can explode if they are exposed to water.

The Alkali Metals are:

Lithium

Symbol: Li
Atomic Number: 3
Atomic Mass: 6.941 amu
Melting Point: 180.54 °C (453.69 K, 356.972 °F)
Boiling Point: 1347.0 °C (1620.15 K, 2456.6 °F)
Number of Protons/Electrons: 3
Number of Neutrons: 4
Classification: Alkali Metal
Crystal Structure: Cubic
Density @ 293 K: 0.53 g/cm³
Color: silvery

Atomic Structure

Number of Energy Levels: 2 First Energy Level: 2 Second Energy Level: 1

Isotopes

Isotope	Half Life
Li-6	Stable
Li-7	Stable

Facts

Date of Discovery: 1817
Discoverer: Johann Arfvedson
Name Origin: From the Greek word lithos (stone)
Uses: batteries, ceramics, lubricants
Obtained From: passing electric charge through melted lithium chloride, spodumene

Sodium

Symbol: Na
Atomic Number: 11
Atomic Mass: 22.98977 amu
Melting Point: 97.72 °C (370.87 K, 207.9 °F)
Boiling Point: 883 °C (1156 K, 1621 °F)
Number of Protons/Electrons: 11
Number of Neutrons: 12
Classification: Alkali Metal
Crystal Structure: Cubic
Density @ 293 K: 0.971 g/cm³
Color: silvery

Atomic Structure

Number of Energy Levels: 3 First Energy Level: 2 Second Energy Level: 8 Third Energy Level: 1

Isotopes

Isotope	Half Life
Na-22	2.6 years
Na-23	Stable
Na-24	14.96 hours

Facts

Date of Discovery: 1807
Discoverer: Sir Humphrey Davy
Name Origin: soda (Na₂CO₃)
Symbol Origin: From the Latin word natrium (sodium)
Uses: medicine, agriculture
Obtained From: table salts and other foods

Potassium

Symbol: K
Atomic Number: 19
Atomic Mass: 39.0983 amu
Melting Point: 63.65 °C (336.8 K, 146.57 °F)
Boiling Point: 774.0 °C (1047.15 K, 1425.2 °F)
Number of Protons/Electrons: 19
Number of Neutrons: 20
Classification: Alkali Metal
Crystal Structure: Cubic
Density @ 293 K: 0.862 g/cm³
Color: silvery

Atomic Structure

Number of Energy Levels: 4 First Energy Level: 2 Second Energy Level: 8 Third Energy Level: 8 Fourth Energy Level: 1

Isotopes

Isotope	Half Life
K-39	Stable
K-40	1.28E9 years
K-41	Stable
K-42	12.4 hours
K-43	22.3 hours

Facts

Date of Discovery: 1807
Discoverer: Sir Humphrey Davy
Name Origin: potash
Symbol Origin: From the Latin word kalium
Uses: glass, soap
Obtained From: minerals (carnallite)

Rubidium

Symbol: Rb
Atomic Number: 37
Atomic Mass: 85.4678 amu
Melting Point: 38.89 °C (312.04 K, 102.002 °F)
Boiling Point: 688.0 °C (961.15 K, 1270.4 °F)
Number of Protons/Electrons: 37
Number of Neutrons: 48
Classification: Alkali Metal
Crystal Structure: Cubic
Density @ 293 K: 1.532 g/cm³
Color: silver

Atomic Structure

Number of Energy Levels: 5 First Energy Level: 2 Second Energy Level: 8 Third Energy Level: 18 Fourth Energy Level: 8 Fifth Energy Level: 1

Isotopes

Isotope	Half Life
Rb-81	4.57 hours
Rb-82	2.25 minutes
Rb-83	86.2 days
Rb-84	32.9 days
Rb-85	Stable
Rb-86	18.65 days
Rb-87	4.8E10 years
Rb-88	17.7 minutes
Rb-89	15.44 minutes
Rb-90	2.6 minutes
Rb-90m	4.3 minutes

Facts

Date of Discovery: 1861
Discoverer: R. Bunsen
Name Origin: From the Latin word rubidus (red)
Uses: catalyst, photocells
Obtained From: lithium production

Cesium

Symbol: Cs
Atomic Number: 55
Atomic Mass: 132.90546 amu
Melting Point: 28.5 °C (301.65 K, 83.3 °F)
Boiling Point: 678.4 °C (951.55005 K, 1253.12 °F)
Number of Protons/Electrons: 55
Number of Neutrons: 78
Classification: Alkali Metal
Crystal Structure: Cubic
Density @ 293 K: 1.873 g/cm³
Color: silver
British Spelling: Caesium
IUPAC Spelling: Caesium

Atomic Structure

Number of Energy Levels: 6 First Energy Level: 2 Second Energy Level: 8 Third Energy Level: 18 Fourth Energy Level: 18 Fifth Energy Level: 8 Sixth Energy Level: 1

Isotopes

Isotope	Half Life
Cs-126	1.6 minutes
Cs-129	1.3 days
Cs-131	9.7 days
Cs-132	6.4 days
Cs-133	Stable
Cs-134	2.1 years
Cs-134m	2.9 hours
Cs-135	2300000.0 years
Cs-136	13.2 days
Cs-137	30.2 years
Cs-138	32.2 minutes
Cs-139	9.3 minutes

Facts

Date of Discovery: 1860
Discoverer: Fustov Kirchoff
Name Origin: From the Latin word caesius (sky blue)
Uses: removes air traces in vacuum tubes
Obtained From: pollucite, lepidolite

Francium

Symbol: Fr
Atomic Number: 87
Atomic Mass: (223.0) amu
Melting Point: 27.0 °C (300.15 K, 80.6 °F)
Boiling Point: 677.0 °C (950.15 K, 1250.6 °F)
Number of Protons/Electrons: 87
Number of Neutrons: 136
Classification: Alkali Metal
Crystal Structure: Cubic
Density @ 293 K: Unknown
Color: Unknown

Atomic Structure

Number of Energy Levels: 7 First Energy Level: 2 Second Energy Level: 8 Third Energy Level: 18 Fourth Energy Level: 32 Fifth Energy Level: 18 Sixth Energy Level: 8 Seventh Energy Level: 1

Isotopes

Isotope	Half Life
Fr-212	20.0 minutes
Fr-221	4.8 minutes
Fr-222	14.3 minutes
Fr-223	21.8 minutes

Facts

Date of Discovery: 1939
Discoverer: Marguerite Derey
Name Origin: After France
Uses: No uses known
Obtained From: decay of actinium