Alkaline and alkali earth metals are basic elements, and the compounds which they form are also basic compounds. When added to water, the solutions shows pH values higher than pH 7. These compounds are used for various purposes, such as reducing or neutralizing the acidity of a medium. alkaline earth metals are group 2 of the periodic tables, whereas alkali metals are in group 2. The major difference between alkaline and alkali is that alkaline earth metals have two valence electrons whereas alkali metals have one valence electron.
What is Alkali
The term alkali is used to name the group 1 elements of the periodic table (lithium, sodium, potassium, etc.). These elements are known as alkali metals. The basic compounds formed from these elements are alkali compounds. An alkali compound is a substance that can form OH– ions when added to water. Therefore, alkali compounds dissolve in water to give solutions having values higher than pH 7. All alkalis have pH values greater than 7. These are basic compounds.
Alkali substances can turn the colour of red litmus into blue colour. They can also react with acidic compounds giving water and salt as the end products. Hence, alkali substances can also be used to neutralize an acidic solution. Alkali metals are very soft, we can cut sodium easily using a knife. These elements have one valence electron in the outermost orbital. Therefore, these elements are very reactive. They can form +1 cations by removing their valence electron.
Concentrated alkali are corrosive and can cause skin irritations. The most common alkalis include carbonates and hydroxides. The reaction between an acid and a hydroxide will give water and salt. The reaction between an acid and a carbonate gives a salt, carbon dioxide gas and water.
Here are a few examples
- Sodium hydroxide (NaOH)
- Potassium hydroxide (KOH)
- Lithium oxide (Li2O)
- Ammonia (NH3)
What is Alkaline
The term Alkaline is used to name group 2 elements of the periodic table. Magnesium, strontium, calcium etc.). These are known as alkaline earth metals. These compounds also form OH– ions when added to water. The solutions of alkaline compounds have higher pH values (>7).
These alkaline compounds also can turn red litmus into the blue colour. They have basic properties. Alkaline earth metals are harder than alkali metals. These elements form +2 cations (positively charged ion) because they have two valence electrons and, a cation can be formed by removing those valance electrons. However, since these electrons are in the s orbital as an electron pair, these elements are not much reactive.
Alkaline earth metals have a lower atomic radius when compared to alkali metals. This is because the number of protons and electrons are higher than the adjacent group 1 element.
Similarities Between Alkali and Alkaline.
- Both have basic properties.
- Both can turn red litmus into blue colour.
- Both types of compounds can form aqueous solutions having >7pH.
- Both can form OH– ions when added to water.
Difference Between Alkali and Alkaline
Alkali: The term Alkali is used to name the group 1 elements of the periodic table.
Alkaline: The term Alkaline earth metal is used to name group 2 elements of the periodic table.
Alkali: Alkali metals are softer.
Alkaline: Alkaline earth metals are harder.
Alkali: Alkali elements have one valence electron.
Alkaline: Alkaline earth metals have two valence electrons.
Alkali: Alkali metals form +1cations.
Alkaline: Alkaline earth metals form +2 cations.
Alkali: Alkali metals have lower ionizing energy.
Alkaline: Alkaline earth metals have higher ionizing energy.
Alkali metals are the elements in group 1 of the periodic table. Alkaline earth metals are the elements in group 2 of the periodic table. Both show basic properties. When added to water, both can form solutions that having higher pH values. The main difference between alkaline and alkali is that alkali metals have one valence electron, whereas alkaline earth metals have two valence electrons.
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