Group 2, The Alkaline Earth Metals | A Level Chemistry | OCR, AQA, Edexcel

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This week we are revising Group 2, The Alkaline Earth Metals

A-Level Chemistry can be tough but fortunately we’ve made this tutorial to help you score the A* you need for questions on everything to do with Group 2, The Alkaline Earth Metals.

Group 2 elements are collectively known as the Alkaline Earth Metals. The outer shell of group 2 elements contains two electrons and is therefore represented by the sub shell s2. Elements in group 2 will lose two electrons to gain a full outer shell of electrons, to form ions with a +2 charge when they react.

As you move down Group 2, the atomic radius of the elements increases. The atomic radius of Group 2 elements decreases because more and more electron shells are being added down the group.

As you move down Group 2, the melting points of the elements decreases. Group 2 elements generally have metallic bonding as they are metallic structures. As you move down the group, the radius of the metal ions increases but the number of delocalised electrons stays the same per atom. The charge of +2 of of the positive ions does not change either. Less energy is needed to break the metallic bonds as the delocalised electrons are further away from the positive nuclei because of an increased ionic radius, therefore there is a decreased attraction between them.

The arrangement of the Group 2 ions in the metal affects the melting point. Between beryllium and radium, there is a change in the melting point trend at magnesium as it has a different crystalline structure.
As you move down Group 2, the first ionisation energy of the elements decreases. More electron shells are added as you move down Group 2 which means the atomic radius increases and therefore the outermost shell becomes further and further away from the positive nucleus. The shielding effect on the outermost electrons also increases due to the presence of more inner electron shells containing electrons. The attraction between the outermost electrons and the nucleus decreases, therefore less energy is required to remove them.

As you move down Group 2, the reactivity of the elements increases. Reactions of Group 2 elements consist of the elements losing electrons to form ions with a +2 charge. As the first ionisation energy decreases as you move down the group, less energy is required to move the electrons, therefore the elements become more reactive.

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