Are Alkaline Earth Metals Reactive? (And Why?)

Yes, alkaline earth metals are reactive. They have two valence electrons, which they readily lose to form positive ions. ¹ They react vigorously with water and oxygen, and their reactivity increases as you move down the group. ²

Well, this was just a simple answer. But there are few more things to know about this topic which will make your concept super clear.

So let’s dive right into it.

Why are alkaline earth metals reactive?

Alkaline earth metals are reactive because they have two valence electrons in their outermost energy level, which makes them highly prone to losing those electrons and forming positive ions. ³ This characteristic results in their strong reactivity with other elements, especially nonmetals, as they readily undergo chemical reactions to achieve a stable electron configuration.

Alkaline earth metals belong to Group 2 of the periodic table, and they include elements such as beryllium, magnesium, calcium, strontium, barium, and radium. ⁴ These metals have two valence electrons, which means their outermost energy level is not complete.

Elements generally strive to achieve a stable electron configuration by gaining or losing electrons. Alkaline earth metals have a tendency to lose their two valence electrons to attain the stable configuration of the previous noble gas.

This readiness to lose electrons makes alkaline earth metals highly reactive. When they come into contact with other elements, especially nonmetals, the alkaline earth metals readily transfer their valence electrons, forming positive ions. ⁵

This reactivity is particularly evident in their reaction with water and oxygen, where they can undergo rapid and often exothermic reactions, resulting in the formation of compounds such as oxides and hydroxides. 

Overall, the reactivity of alkaline earth metals arises from their electron configuration and their propensity to achieve a stable state by losing electrons.

Are alkaline earth metals more or less reactive than alkali metals?

Alkali metals are generally more reactive than alkaline earth metals. ⁶ Alkali metals, such as lithium, sodium, and potassium, have a single valence electron in their outermost energy level, which they readily lose to form positive ions. This low ionization energy and high reactivity distinguish them from the alkaline earth metals, which have two valence electrons and exhibit lower reactivity.

Alkali metals, found in Group 1 of the periodic table, are highly reactive due to their low ionization energies. ⁷ They have a strong tendency to lose their single valence electron and form stable cations. This reactivity is showcased by their vigorous reactions with water, oxygen, and halogens. 

Alkaline earth metals, on the other hand, are less reactive compared to alkali metals. While they still possess reactivity due to their two valence electrons, the higher ionization energies and smaller atomic radii of alkaline earth metals result in less pronounced reactivity.

The presence of two valence electrons in alkaline earth metals requires a higher amount of energy to remove those electrons compared to alkali metals. This higher ionization energy and increased stability of the two valence electrons contribute to the reduced reactivity of alkaline earth metals.

However, it is important to note that alkaline earth metals are still considered reactive, especially when compared to other groups of elements in the periodic table. ⁸ Their reactivity manifests in various chemical reactions and the formation of compounds such as oxides, hydroxides, and salts.

Reactivity trend of alkaline earth metals

The reactivity of alkaline earth metals generally increases as you move down the group in the periodic table. Beryllium (Be), the first element in the alkaline earth metal group, is the least reactive, while radium (Ra), the last element, is the most reactive. ⁹

As you go down the group, the atomic size of the alkaline earth metals increases due to the addition of more energy levels. The increase in atomic size results in a weaker attraction between the positively charged nucleus and the valence electrons, leading to a lower ionization energy. ¹⁰ This lower ionization energy makes it easier for the outermost electrons to be lost, increasing reactivity.

Thus, the combination of larger atomic size and lower ionization energy as you move down the group contributes to the increasing reactivity of alkaline earth metals. This trend is observed in their reactions with water, oxygen, and other substances, where the reactivity and chemical behavior become more pronounced as you progress from beryllium to radium.

Further reading

Is Chlorine Flammable?
Why is Salt (NaCl) Soluble in Water?
Is CH4 (Methane) Soluble in Water?
Why is Sugar (Sucrose) Soluble in Water?
Is BaSO4 (Barium Sulfate) Soluble in Water?

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