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📝 Alkaline Earth elements

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The Group 2 elements magnesium to barium are typical metals with high melting points and they are good conductors of heat and electricity. The overall trend is for melting points and boiling points to decrease down group II.
Progressing down Group 2 from magnesium to barium, the atomic radius increases. This is due to the addition of an extra shell of electrons for each element as the group is descended. The Group 2 elements magnesium to barium reacts with water to produce hydrogen gas and the metal hydroxide, which may be only slightly soluble. The Group 2 elements magnesium to barium burns in air to form white solid oxides. These oxides form hydroxides with water. The hydroxides get more soluble in water going down the group, so their solutions can become more alkaline. The sulfates of Group 2 elements get less soluble in water going down the group. Reactivity of the elements with oxygen or water increases down Group 2 as the first and second ionisation energies decrease. The Group 2 carbonates and nitrates get more resistant to thermal decomposition descending the group.
Many of the compounds of Group 2 elements have important uses. Limestone, which mainly contains calcium carbonate is used as a building material and is used to make cement, which is a component in the mixtures that make concrete and mortar. Slaked lime (calcium hydroxide) is used to neutralise acids in acidic soil. Magnesium hydroxide is almost insoluble and is sold as a suspension in water. In this form it is known as «milk of magnesia.» It is taken to reduce indigestion as it neutralizes stomach acidity.
Magnesium sulphate is used to counter magnesium deficiency. As magnesium sulphate is soluble, it is a good source of magnesium ions which the body needs. Barium sulphate can be eaten as part of a «barium meal.» Barium is good at absorbing X-rays and so when the barium sulphate gets to the gut the outline of the gut can be located using X-rays. Although barium ions are very toxic, this technique is harmless because barium sulphate is completely insoluble.