# group 2 elements reaction with water

If this is the first set of questions you have done, please read the introductory page before you start. 2Mg (s) + O 2(g) → 2MgO (s) Thermal stability of carbonates and nitrates. There is an additional reason for the lack of reactivity of beryllium compared with the rest of the Group. 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 - calcium hydroxide is slightly soluble). 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. The Mg would burn with a bright white flame. The activation energy for a reaction is the minimum amount of energy which is needed in order for the reaction to take place. to generate metal oxides. Looking at the activation energies for the reactions. Group 17: Halogens This page discusses the reactions of the Group 2 elements (beryllium, magnesium, calcium, strontium and barium) with water, using these reactions to describe the trend in reactivity in Group 2. If it reacts with steam, the metal oxide is formed. This is mainly due to a decrease in ionisation energy as you go down the Group. Group 2 Elements, Alkaline Earth metals, reaction of alkaline earth metals in water, examples and step by step demonstration $Mg_{(s)} + 2H_2O_{(l)} \rightarrow Mg(OH)_{2(s)} + H_{2(g)} \label{2}$. 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. Magnesium burns in steam to produce white magnesium oxide and hydrogen gas. Missed the LibreFest? It uses these reactions to explore the trend in reactivity in Group 2. Calcium, for example, reacts fairly vigorously with cold water in an exothermic reaction. Similarly, calculating the enthalpy changes for the reactions between calcium, strontium or barium and cold water reveals that the amount of heat evolved in each case is almost exactly the same—about -430 kJ mol-1. However, the oxide layer breaks up above 750°C and exposes the beryllium metal surface below it, and so the protection then fails. 1.3.2 (b) Reactivity of Group 2 Elements. Group 2 elements generally react to form compounds in which the group 2 element has an oxidation state of +2, beryllium will also do this but it has a tendency to form covalent rather than ionic compounds. Notice that the ionization energies dominate this - particularly the second ionization energies. When Group 2 metals react to form oxides or hydroxides, metal ions are formed. Reactivity of group 2 metals increases down the group Magnesium burns in steam to produce magnesium oxide and hydrogen. Ionization energies fall down the group. the first + second ionisation energies. After several minutes, some bubbles of hydrogen form on its surface, and the coil of magnesium ribbon usually floats to the surface. The general formula for these reactions is M (OH)2 (where M is the group 2 element). Have questions or comments? The reason for the increase in reactivity must again lie elsewhere. the atomization energy of the metal. This page looks at the reactions of the Group 2 elements - beryllium, magnesium, calcium, strontium and barium - with air or oxygen. On the whole, the metals burn in oxygen to form a simple metal oxide. 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. However, the oxide layer breaks up above 750°C and exposes the beryllium metal surface below it, and so the protection then fails. REACTIONS OF THE GROUP 2 ELEMENTS WITH WATER. Beryllium reacts with steam at high temperatures (typically around 700°C or more) to give white beryllium oxide and hydrogen. This leads to lower activation energies, and therefore faster reactions. As mentioned earlier, many Group 1 and Group 2 oxides react with water to form metal hydroxides. However, only the magnesium reaction actually happens. $Mg_{(s)} + H_2O_{(g)} \rightarrow MgO_{(s)} + H_{2(g)} \label{1}$. 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 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.

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