# group 2 elements reaction with water

However, a researcher in the development of nuclear fusion pointed out to me that a lot of work is being done on the reaction between beryllium and steam because it could be a safety issue in reactor design, and sent me a photo showing the result of exposing beryllium to steam at 800°C. The reason for the increase in reactivity must again lie elsewhere. The formation of the ions from the original metal involves various stages all of which require the input of energy - contributing to the activation energy of the reaction. 1.3.2 (b) Reactivity of Group 2 Elements. Looking at the activation energies for the reactions. As a general rule, if a metal reacts with cold water, the metal hydroxide is produced. Notice that the ionization energies dominate this - particularly the second ionization energies. Beryllium has a strong resistant layer of oxide on its surface which lowers its reactivity at ordinary temperatures. Ionisation energies fall as you go down the Group. These stages involve the input of: the atomisation energy of the metal. Very clean magnesium ribbon has a mild reaction with cold water, given below. If this is the first set of questions you have done, please read the introductory page before you start. These metals react with cold water with increasing vigor to give the metal hydroxide and hydrogen. Again the reactivity increases down the group, all forming a white oxide. This means that the alkali metals all have similar chemical properties . (Equation just like the magnesium one below.). For example, Magnesium reacts with water to form Magnesium Hydroxide and Hydrogen gas in the following equation: Very clean magnesium ribbon has a very slight reaction with cold water. The explanation for the different reactivities must lie somewhere else. However, the reaction is short-lived because the magnesium hydroxide formed is almost insoluble in water and forms a barrier on the magnesium preventing further reaction. The graph shows the effect of these important energy-absorbing stages as you go down Group 2. Summarising the reason for the increase in reactivity as you go down the Group. This means that few teachers will ever have handled it - I certainly haven't. An enthalpy change is negative if heat is evolved, and positive if it is absorbed. The reactions become easier as the energy needed to form positive ions falls. Group 2 reactions Reactions with water. This is mainly due to a decrease in ionization energy down the group. The LibreTexts libraries are Powered by MindTouch® and are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. This Module addressed why it is difficult to observe a tidy pattern of this reactivity. I apologise for my part in this. Carbonates. However, only the magnesium reaction actually happens. There is an additional reason for the lack of reactivity of beryllium compared with the rest of the Group. Because it gets easier to form the ions, the reactions will happen more quickly. $Mg_{(s)} + 2H_2O_{(l)} \rightarrow Mg(OH)_{2(s)} + H_{2(g)} \label{2}$. The Facts. However, the oxide layer breaks up above 750°C and exposes the beryllium metal surface below it, and so the protection then fails. In each case, the aqueous metal hydroxide and hydrogen gas are produced, as shown: $2X (s) + 2H_2O (l) \rightarrow 2XOH (aq) + H_2 (g)$ where $$X$$ is any Group 1 metal. However, the magnesium reaction is much faster. REACTIONS OF THE GROUP 2 ELEMENTS WITH WATER. Group 2 elements (beryllium, magnesium, calcium, strontium and barium) react oxygen. The equation for the reactions of any of these metals would be: The hydroxides aren't very soluble, but they get more soluble as you go down the Group. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. It definitely reacts. Magnesium burns in steam to produce white magnesium oxide and hydrogen gas. For more information contact us at info@libretexts.org or check out our status page at https://status.libretexts.org. The hydroxide solubilities increase down the group. This is the energy needed to break the bonds holding the atoms together in the metallic lattice. Reactions of the Group 2 elements with water REACTIONS OF THE GROUP 2 ELEMENTS WITH WATER This page looks at the reactions of the Group 2 elements - beryllium, magnesium, calcium, strontium and barium - with water (or steam). The overall trend, for the reactivity of Group 2 metals with water, is an increase down the group. The alkaline earth metals are six chemical elements in group 2 of the periodic table.They are beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). Hydrogen is given off during these reactions. Since its a hydroxide, you are right in saying that its an alkaline solution. This page looks at the reactions of the Group 2 elements - beryllium, magnesium, calcium, strontium and barium - with air or oxygen. Beryllium reacts with steam at high temperatures (typically around 700°C or more) to give white beryllium oxide and hydrogen. the first + second ionization energies. 2Mg (s) + O 2(g) → 2MgO (s) Thermal stability of carbonates and nitrates. Magnesium burns in steam to produce white magnesium oxide and hydrogen gas. Legal. It does not matter how exothermic the reaction would be once it got started - if there is a high activation energy barrier, the reaction will take place very slowly, if at all. When Group 2 metals react to form oxides or hydroxides, metal ions are formed. Calcium, for example, reacts fairly vigorously with cold water in an exothermic reaction. The calcium hydroxide formed shows up mainly as a white precipitate (although some does dissolve). Bubbles of hydrogen gas are given off, and a white precipitate (of calcium hydroxide) is formed, together with an alkaline solution (also of calcium hydroxide, which is slightly water-soluble). It doesn't matter how exothermic the reaction would be once it got started - if there is a high activation energy barrier, the reaction will take place very slowly, if at all. The activation energy for a reaction is the minimum amount of energy which is needed in order for the reaction to take place. If it reacts with steam, the metal oxide is formed. That means that textbook (or these days, web) statements about it never get checked, and are just passed on regardless of their accuracy. The thermal stability of Group II carbonates increases as we descend the group. The Group 2 metals become more reactive towards water as you go down the Group. If you calculate the enthalpy change for the possible reactions between beryllium or magnesium and steam, you come up with these answers: Notice that both possible reactions are strongly exothermic, giving out almost identical amounts of heat. It explains why it is difficult to observe many tidy patterns. After several minutes, some bubbles of hydrogen form on its surface, and the coil of magnesium ribbon usually floats to the surface. These stages involve the input of: After this, there will be a number of steps which give out heat again - leading to the formation of the products, and overall exothermic reactions.