Group 2 reactions Reactivity of group 2 metals increases down the group Mg will also react slowly with oxygen without a flame. Lithium is the only metal in Group 1 to form a nitride. For more information contact us at info@libretexts.org or check out our status page at https://status.libretexts.org. CCEA Chemistry. Beryllium, magnesium and calcium don't form peroxides when heated in oxygen, but strontium and barium do. 2Li(s) + Cl 2 (g) → 2LiCl(s) A similar reaction takes place with the other elements of group 7. In each case, you will get a mixture of the metal oxide and the metal nitride. 2Mg + O2 2MgO This needs to be cleaned off by emery paper before doing reactions with Mg ribbon. Beryllium is reluctant to burn unless it is in the form of dust or powder. The general equation for the Group is: \[ 3X_{(s)} + N_{2(g)} \rightarrow X_3N_{2(s)}\]. The size of the lattice energy depends on the attractions between the ions. Beryllium, magnesium and calcium don't form peroxides when heated in oxygen, but strontium and barium do. The group 1 elements react with oxygen from the air to make metal oxides. In each case, you will get a mixture of the metal oxide and the metal nitride. The Facts The reactions with oxygen Formation of simple oxides Nitrogen is fairly unreactive because of the very large amount of energy is required to break the triple bond joining the two atoms in the nitrogen molecule, N2. Now imagine bringing a small 2+ ion close to the peroxide ion. Strontium: I have only seen this burn on video. questions on the reactions of Group 2 elements with air or oxygen, © Jim Clark 2002 (last modified February 2015), reactions of these metals with water (or steam). This is clearly seen if we observe the reactions of magnesium and calcium in water. All of these processes absorb energy. Lithium has by far the smallest ion in the Group, and so lithium nitride has the largest lattice energy of any possible Group 1 nitride. Beryllium has a very strong (but very thin) layer of beryllium oxide on its surface, and this prevents any new oxygen getting at the underlying beryllium to react with it. The general trend in acidity in oxides of the Period 3 elements as we go across the period from left (Group 1) to right (Group 17): basic oxides (Group 1, 2) → amphoteric oxide (Al 2 O 3) → acidic oxides (oxyacids) The same trend can be seen in each period of the Periodic table and we have: Bases react with acids such is HCl: e.g. It explains why it is difficult to observe many tidy patterns. Formation of simple oxides. Unit AS 2: Further Physical and inorganic Chemistry and an Introdution to Organic Chemistry. This is mainly due to a decrease in ionization energy down the group. Energy is evolved when the ions come together to produce the crystal lattice. with \(X\) representing any group 2 metal. In each case, you will get a mixture of the metal oxide and the metal nitride. We say that the positive ion polarizes the negative ion. Reactions with oxygen … We say that the positive ion polarises the negative ion. This property is known as deliquescence. While it would be tempting to say that the reactions get more vigorous as you go down the Group, but it is not true. For example, Magnesium reacts with Oxygen to form Magnesium Oxide the formula for which is: 2Mg (s) + O 2 (g) 2MgO (s) This is a redox reaction. Reactions with oxygen. This works best if the positive ion is small and highly charged - if it has a high charge density. 2:07 understand how displacement reactions involving halogens and halides provide evidence for the trend in reactivity in Group 7; 2:08 (Triple only) explain the trend in reactivity in Group 7 in terms of electronic configurations (c) Gases in the atmosphere. Why do some metals form peroxides on heating in oxygen? It is almost impossible to find any trend in the way the metals react with oxygen. You will need to use the BACK BUTTON on your browser to come back here afterwards. In the whole of Group 2, the attractions between the 2+ metal ions and the 3- nitride ions are big enough to produce very high lattice energies. For example, Barium peroxide can form because the barium ion is so large that it doesn't have such a devastating effect on the peroxide ions as the metals further up the Group. This energy has to be recovered from somewhere to give an overall exothermic reaction - if the energy can't be recovered, the overall change will be endothermic and won't happen. This energy has to be recovered from somewhere to give an overall exothermic reaction - if the energy can't be recovered, the overall change will be endothermic and will not happen. There are no simple patterns. Lithium is the only metal in Group 1 to form a nitride. Strontium and barium will also react with oxygen to form strontium or barium peroxide. Reactions with dilute hydrochloric acid All the metals react with dilute hydrochloric acid to give bubbles of hydrogen and a colourless solution of the metal chloride. Why do some metals form peroxides on heating in oxygen? \[ 2Mg_{(s)} + O_{2(g)} \rightarrow 2MgO_{(s)}\], \[ 3Mg_{(s)} + N_{2(g)} \rightarrow Mg_3N_{2(s)}\]. As I said earlier, they are powerful reducing age… As you go down the Group and the positive ions get bigger, they don't have so much effect on the peroxide ion. The activation energy will fall because the ionisation energies of the metals fall. Beryllium: I can't find a reference anywhere (text books or internet) to the colour of the flame that beryllium burns with. This page looks at the reactions of the Group 2 elements - beryllium, magnesium, calcium, strontium and barium - with air or oxygen. You might possibly be able to imagine a trace of very pale greenish colour surrounding the white flame in the third video, but to my eye, they all count as a white flame. The reactions with oxygen. Watch the recordings here on Youtube! Only in lithium's case is enough energy released to compensate for the energy needed to ionise the metal and the nitrogen - and so produce an exothermic reaction overall. The excess energy evolved makes the overall process exothermic. Representative reactions of alkaline earth metals. The familiar white ash you get when you burn magnesium ribbon in air is a mixture of magnesium oxide and magnesium nitride (despite what you might have been told when you were first learning Chemistry!). The strontium equation would look just the same. information contact us at info@libretexts.org, status page at https://status.libretexts.org. It explains why it is difficult to observe many tidy patterns. It would be quite untrue to say that they burn more vigorously as you go down the Group. Only in lithium's case is enough energy released to compensate for the energy needed to ionize the metal and the nitrogen - and so produce an exothermic reaction overall. The excess energy evolved makes the overall process exothermic. There are no simple patterns in the way the metals burn. Acid-Base reactions are not Redox reactions because there are no changes in Oxidation number. However, in a reaction with steam it forms magnesium oxide and hydrogen. Mg ribbon will often have a thin layer of magnesium oxide on it formed by reaction with oxygen. The strontium equation would look just the same. It is almost impossible to find any trend in the way the metals react with oxygen. In all the other cases in Group 1, the overall reaction would be endothermic. The chemical properties of Group2 elements are dominated by the strong reducing power of the metals. The equations for the reactions: 1.3.2 (a) Redox Reactions of Group 2 Metals. 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. To be able to make any sensible comparison, you would have to have pieces of metal which were all equally free of oxide coating, with exactly the same surface area and shape, exactly the same flow of oxygen around them, and heated to exactly the same extent to get them started. All group 2 elements want to lose 2 electrons and all group 6 elements (oxygen) want to gain 2 electrons. Mixtures of barium oxide and barium peroxide will be produced. The peroxide ion, O22- looks like this: The covalent bond between the two oxygen atoms is relatively weak. In this case, though, the effect of the fall in the activation energy is masked by other factors - for example, the presence of existing oxide layers on the metals, and the impossibility of controlling precisely how much heat you are supplying to the metal in order to get it to start burning. Strontium forms this if it is heated in oxygen under high pressures, but barium forms barium peroxide just on normal heating in oxygen. 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