Alkali Metals-Properties, Electronic Configuration, and Periodic Trends

Alkali metals, a group of chemical elements found in the first column of the periodic table, possess a unique and intriguing characteristic- they are highly reactive. Their ability to easily lose their outermost electron, resulting in the formation of positively charged ions, is a fascinating aspect of their reactivity.

Read Examples of Alkali Metals

Alkali metals are called alkalis because they readily form alkaline solutions when they react with water. This reaction produces hydroxide ions, which are characteristic of alkaline substances.
‘ alkali’ refers to a basic or alkaline substance, and these metals vividly demonstrate this property. Their ability to form strong bases when combined with water distinguishes them from other metals. It underscores their crucial role in various chemical and industrial processes, making them a topic of significant relevance.

Physical Properties of Alkali Metals

1. Alkali metals are typically soft and can be easily cut with a knife. This softness increases down the group.
2. They have relatively low densities compared to most other metals. The density generally increases down the group.
3. Alkali metals have low melting and boiling points compared to other metals. These points decrease down the group.
4. They exhibit high thermal conductivity, meaning they can efficiently transfer heat.
5. Alkali metals have a shiny, metallic appearance, resembling silver.
6. They are malleable, meaning they can be hammered or pressed into thin sheets, and ductile, meaning they can be drawn into wires.
7. Alkali metals exhibit a characteristic metallic luster, reflecting light well.

Position in Periodic Table

Alkali metals reside in Group 1 of the periodic table, also known as the alkali metal group. This group includes elements such as lithium(Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr). They are placed on the far left side of the periodic table, preceding the alkaline earth metals.)

Occurrence

Alkali metals are relatively abundant in nature. They are typically found in compound form rather than as pure elements. Sodium is widely distributed in minerals such as halite (rock salt) and seawater. Sodium is also present in common salt or sodium chloride.

Potassium is present in minerals like feldspar, carnallite, and sylvite and in plant and animal tissues. Lithium occurs in various minerals, including spodumene, lepidolite, and petalite, and is also found in small amounts in seawater and certain mineral springs.

Rubidium and cesium are primarily obtained from lepidolite, pollucite, and carnallite. Francium is extremely rare and radioactive, with its occurrence limited to trace amounts in uranium and thorium ores.

Electronic configuration

The general electronic configuration of alkali metals is [Noble gas] ns¹. Here are the electronic configurations of different alkali metals:

Element	Atomic Number	Electron Configuration
Lithium	3	1s² 2s¹
Sodium	11	1s² 2s² 2p⁶ 3s¹
Potassium	19	1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹
Rubidium	37	1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s¹
Cesium	55	1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s¹
Francium	87	1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s¹

General Trends in Periodic Table

Alkali metals exhibit several general trends in the periodic table:

1. Atomic Size – Alkali metals have the largest atomic sizes in their respective periods due to only one electron in their outermost shell. As you move down the group, atomic size increases due to the addition of energy levels.
2. Reactivity – Alkali metals are highly reactive due to their tendency to lose an electron easily. This reactivity increases down the group, with francium being the most reactive alkali metal.
3. Melting and Boiling Points – Alkali metals have relatively low melting and boiling points compared to other metals, and these points decrease down the group.
4. Density -Alkali metals are less dense than transition metals, increasing their density down the group.
5. Ionization Energy – Alkali metals have low ionization energies, requiring relatively little energy to remove their outermost electron. Ionization energy decreases down the group.