Beryllium: I can't find a reference anywhere (text books or internet) to the colour of the flame that beryllium burns with. Strontium forms this if it is heated in oxygen under high pressures, but barium forms barium peroxide just on normal heating in oxygen. What the metals look like when they burn is a bit problematical! The peroxide ion, O22- looks like this: The covalent bond between the two oxygen atoms is relatively weak. Mg ribbon will often have a thin layer of magnesium oxide on it formed by reaction with oxygen. We say that the positive ion polarizes the negative ion. Strontium forms this if it is heated in oxygen under high pressures, but barium forms barium peroxide just on normal heating in oxygen. 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. Atomic and physical properties . The has been reduced from 0 to -2. This works best if the positive ion is small and highly charged - if it has a high charge density. There are no simple patterns. This Module addressed why it is difficult to observe a tidy pattern of this reactivity. You could argue that the activation energy will fall as you go down the Group and that will make the reaction go faster. Why do these metals form nitrides on heating in air? This works best if the positive ion is small and highly charged - if it has a high charge density. 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. Beryllium is reluctant to burn unless it is in the form of dust or powder. You could argue that the activation energy will fall as you go down the Group and that will make the reaction go faster. 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. When these metals (M) are heated in oxygen they burn vigorously to produce a white ionic oxide, M2+O2-. This is clearly seen if we observe the reactions of magnesium and calcium in water. 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. Ions of the metals at the top of the Group have such a high charge density (because they are so small) that any peroxide ion near them falls to pieces to give an oxide and oxygen. . Beryllium is reluctant to burn unless it is in the form of dust or powder. Reaction with halogens. (3 Marks) (d) Heating Group 2 Carbonates, Such As CaCO3 Leads To Decomposition. It is also reluctant to start burning, but then burns with an intense almost white flame with red tinges especially around the outside. reactivity trend down group 2 with water. Have questions or comments? The equations for the reactions: This property is known as deliquescence. (3 Marks) (c) Draw The Molecular Orbital Diagram For Peroxide Ion. increases down the group because it becomes more easy to lose the two electrons. Lithium is the only metal in Group 1 to form a nitride. CCEA Chemistry. Discusses trends in atomic radius, ionisation energy, electronegativity and melting point of the Group 2 elements. Beryllium, magnesium and calcium don't form peroxides when heated in oxygen, but strontium and barium do. Ions of the metals at the top of the Group have such a high charge density (because they are so small) that any peroxide ion near them falls to pieces to give an oxide and oxygen. For example, the familiar white ash you get when you burn magnesium ribbon in air is a mixture of magnesium oxide and magnesium nitride. On the whole, the metals burn in oxygen to form a simple metal oxide. a) Virtually no reaction occurs between magnesium and cold water. The general formula for this reaction is MO (where M is the group 2 element). strontium and water reaction. 2:09 know the approximate percentages by volume of the four most abundant gases in dry air But how reactive a metal seems to be depends on how fast the reaction happens (i.e., Kinetics) - not the overall amount of heat evolved (i.e., Thermodynamics). CaO(s) + H2O(l) ——> Ca(OH)2(s) Hydroxides • basic strength also increases down group • this is because the solubility increases • the metal ions get larger so charge density decreases • there is a lower attraction between the OH¯ ions and larger dipositive ions This is then well on the way to forming a simple oxide ion if the right-hand oxygen atom (as drawn below) breaks off. The reactions of the Group 2 metals with air rather than oxygen is complicated by the fact that they all react with nitrogen to produce nitrides. Representative reactions of alkaline earth metals. The reactions of the Group 2 elements proceed more readily as the energy needed to form positive ions falls. The size of the lattice energy depends on the attractions between the ions. (i) The Reactions of Group 2 Elements with Oxygen. Mg ribbon will often have a thin layer of magnesium oxide on it formed by reaction with oxygen. 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. Looks at the trends in the reactions between the Group 2 elements and water. It is easier for group 2 elements to lose 2 electrons the further away the electrons are from the nucleus ( as you go down there are more shells), hence the trend is as you go down the group 2 elements the reactivity with oxygen increases. The size of the lattice energy depends on the attractions between the ions. Unit AS 2: Further Physical and inorganic Chemistry and an Introdution to Organic Chemistry. M = Mg, Ca, Sr,Ba --> I will be using 'M' as the general symbol for a Group II element in this topic. Watch the recordings here on Youtube! Nitrogen is often thought of as being fairly unreactive, and yet all these metals combine with it to produce nitrides, X3N2, containing X2+ and N3- ions. Ca + Cl 2 → CaCl 2. They react violently in pure oxygen producing a white ionic oxide. 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. Mg(s) + H2O(g) → MgO(s) + H2(g) b) Calcium is more reactive. 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. 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. 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. The group 2 elements react vigorously with oxygen in a redox reaction, forming an oxide with the general formula where is the group 2 element. MgO + 2HCl MgCl 2 + H 2O Reactions with oxygen. It can't be done! Barium: I have also only seen this burn on video, and although the accompanying description talked about a pale green flame, the flame appeared to be white with some pale green tinges. If this is the first set of questions you have done, please read the introductory page before you start. This is in contrast to what happens in Group 1 of the Periodic Table (lithium, sodium, potassium, rubidium and caesium). There is an increase in the tendency to form the peroxide as you go down the Group. There is an increase in the tendency to form the peroxide as you go down the Group. In each case, you will get a mixture of the metal oxide and the metal nitride. PERIODIC TABLE GROUP 2 MENU . Electrons in the peroxide ion will be strongly attracted towards the positive ion. 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. Further along though, a strong S-O bond keeps this together and more H+ is generated. REACTIONS OF THE GROUP 2 ELEMENTS WITH AIR OR OXYGEN This page looks at the reactions of the Group 2 elements - beryllium, magnesium, calcium, strontium and barium - with air or oxygen. Group 2 elements (beryllium, magnesium, calcium, strontium and barium) react oxygen. This page looks at the reactions of the Group 2 elements - beryllium, magnesium, calcium, strontium and barium - with air or oxygen. Reactions with oxygen. As you go down the Group and the positive ions get bigger, they don't have so much effect on the peroxide ion. Unless otherwise noted, LibreTexts content is licensed by CC BY-NC-SA 3.0. 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. Formation of simple oxides. 2Mg + O2 2MgO This needs to be cleaned off by emery paper before doing reactions with Mg ribbon. 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. Anhydrous calcium chloride is a hygroscopic substance that is used as a desiccant. The reactions of the alkaline earth metals with oxygen are less complex than those of the alkali metals. . 2.11 Group II elements and their compounds. You haven't had to heat them by the same amount to get the reactions happening. $2Mg_{(s)} + O_{2(g)} \rightarrow 2MgO_{(s)}$, $3Mg_{(s)} + N_{2(g)} \rightarrow Mg_3N_{2(s)}$. The general equation for the Group is: $3X_{(s)} + N_{2(g)} \rightarrow X_3N_{2(s)}$. In this video I take a look at some of the different ways in which group 2 elements can react. For more information contact us at info@libretexts.org or check out our status page at https://status.libretexts.org. Lithium is the only metal in Group 1 to form a nitride. Why do some metals form peroxides on heating in oxygen? Exposed to air, it will absorb water vapour from the air, forming a solution. As a whole, metals when burns with the oxygen form a simple metal oxide. All of these processes absorb energy. Magnesium, of course, burns with a typical intense white flame. Mg burns with a bright white flame. The Facts The reactions with oxygen Formation of simple oxides oxygen, to forma metal oxide with the formula MO where M is the metal and O is oxygen ... (OH)2 is only sparingly soluble. Beryllium, magnesium and calcium don't form peroxides when heated in oxygen, but strontium and barium do. 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: All of these processes absorb energy. The activation energy will fall because the ionization energies of the metals fall. When the crystal lattices form, so much energy is released that it more than compensates for the energy needed to produce the various ions in the first place. Mg + 2 H2O Mg(OH) 2 + H2 This is a much slower reaction than the reaction with steam and there is no flame. The alkali metals react with oxygen. Question: (a) Write Chemical Equations For The Reactions Of Oxygen With Group 1 Metals And Group 2 Metals Respectiv (4 Marks) (b) Discuss The Trend Of Thermal Stability Of Group 1 And Group 2 Peroxides. Acid-Base reactions are not Redox reactions because there are no changes in Oxidation number. In all the other cases in Group 1, the overall reaction would be endothermic. 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. The speed is controlled by factors like the presence of surface coatings on the metal and the size of the activation energy. Strontium and barium will also react with oxygen to form strontium or barium peroxide. Reaction with water Most Group II oxides react with water to produce the hydroxide e.g. A high charge density simply means that you have a lot of charge packed into a small volume. Those reactions don't happen, and the nitrides of sodium and the rest aren't formed. 2M(s) + O All Group 2 elements tarnish in air to form a coating of the metal oxide. Magnesium, on the other hand, has to be heated to quite a high temperature before it will start to react. The strontium equation would look just the same. Water: The group 2 metals will burn in oxygen. The speed is controlled by factors like the presence of surface coatings on the metal and the size of the activation energy. It is then so hot that it produces the typical intense white flame. 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. My best guess would be the same sort of silvery sparkles that magnesium or aluminium powder burn with if they are scattered into a flame - but I don't know that for sure. There are no simple patterns in the way the metals burn. Energy is evolved when the ions come together to produce the crystal lattice. 2Mg + O2 2MgO This needs to be cleaned off by emery paper before doing reactions with Mg ribbon. Anything else that I could find in a short clip from YouTube involved a flame test for a barium compound, irrespective of how it was described in the video. information contact us at info@libretexts.org, status page at https://status.libretexts.org. An example reaction is shown below: In this reaction, the is oxidised from 0 to +2. Now imagine bringing a small 2+ ion close to the peroxide ion. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. Strontium and barium will also react with oxygen to form strontium or barium peroxide. It explains why it is difficult to observe many tidy patterns. The excess energy evolved makes the overall process exothermic. It reacts with cold water to produce an alkaline solution of calcium hydroxide and hydrogen gas is released. 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. Strontium: I have only seen this burn on video. Barium forms barium peroxide (BaO 2) because the larger O 2 2− ion is better able to separate the large Ba 2+ ions in the crystal lattice. The activation energy will fall because the ionisation energies of the metals fall. The reactions of the Group 2 metals with air rather than oxygen is complicated by the fact that they all react with nitrogen to produce nitrides. The chemical properties of Group2 elements are dominated by the strong reducing power of the metals. Why do some metals form peroxides on heating in oxygen? Reactivity increases down the group. 1.3.2 (a) Redox Reactions of Group 2 Metals. To find the trend of reactions of metals with oxygen is almost impossible. While it would be tempting to say that the reactions get more vigorous as you go down the Group, but it is not true. Reactions. This is mainly due to a decrease in ionization energy down the group. Describe the trend in the reactivity of group 2 elements with chlorine as you descend down the group. In each case, you will get a mixture of the metal oxide and the metal nitride. It would be quite untrue to say that they burn more vigorously as you go down the Group. Those reactions don't happen, and the nitrides of sodium and the rest are not formed. Once started, the reactions with Oxygen and Chlorine are vigorous: 2Mg(s) + O 2 (g) è2MgO(s) Ca(s) + Cl 2 (g) è CaCl 2 (s) All the metals except Beryllium form oxides in air at room temperature which dulls the surface of the metal. This is compared to non-metals when the reactivity decreases working down a non-metal group such as group 7. Their ions only carry one positive charge, and so the lattice energies of their nitrides will be much less. As you go down the Group and the positive ions get bigger, they don't have so much effect on the peroxide ion. 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. with $$X$$ representing any group 2 metal. . (h) trend in general reactivity of Group 1 and Group 2 metals; Northern Ireland. There are also problems with surface coatings. The lattice energy is greatest if the ions are small and highly charged - the ions will be close together with very strong attractions. The Group II elements are powerful reducing agents. REACTIONS OF THE GROUP 2 ELEMENTS WITH AIR OR OXYGEN. 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. Their ions only carry one positive charge, and so the lattice energies of their nitrides will be much less. 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). $Ba_{(s)} + O_{2(s)} \rightarrow BaO_{2(s)}$. Oxygen: All of the elements in group 2 react vigorously with Oxygen, the product of which is an ionic oxide. The overall amount of heat evolved when one mole of oxide is produced from the metal and oxygen also shows no simple pattern: If anything, there is a slight tendency for the amount of heat evolved to decrease as you go down the Group. This leads to lower activation energies, and therefore faster reactions. Missed the LibreFest? 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