Unit 35 The Alkaline Earth Metals

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Unit 35

The Alkaline Earth Metals

The physical and chemical properties of the group II elements, the Alkaline Earth metals.

That they have similar chemical and physical properties based on their electronic configuration.

Their reactions and formation of compounds with oxygen.

Their reactions and formation of compounds with water.

Their reactions and formation of compounds with the halogens.

That their reactivity increases as you descend the group.

That the Alkaline Earth metals react with other non metals during the formation of ionic compounds

The common uses of the Alkaline Earth metals and their ionic compounds.

Alkaline, Earth, Metals, Beryllium, Magnesium, Calcium, Rubidium, Strontium, Physical, Chemical, Properties, Ionic, Compounds, Non metals, Ions, Reactions, Oxides, Hydroxide, Halides, Atoms, Chemical, Bond & Reactivity. Unit 35: The Alkaline Earth Metals web: www.science-interactive.co.uk email: sales@science-interactive.co.uk Science Interactive LTD PO BOX 50764 LONDON NW6 9AT Click mouse to begin Science Interactive LTD Copyright 2005 Understand: Keywords:

Physical properties of the Alkaline Earth metals one Group II of the periodic table contains a family of moderately r_________ metals known as the Alkaline Earth metals . This group contains Beryllium, Magnesium, Calcium and Strontium. They are not found in their pure state like gold, but are found tied up in ionic compounds. They have relatively low melting and boiling points and densities, when compared to transitional metals like c________, iron and titanium. Name two compounds that contain calcium and magnesium ? The Alkaline Earth metals: Science Interactive LTD Copyright 2005 Word bank: reactive copper The Alkaline Earth metals have similar chemical properties because they all have two electrons in their outer shell. Their reactivity with non metals increases as you descend the group along with the size of their atoms. Their melting and boiling points also rise as you descend the group. The Alkaline Earth metals Notes Diagram Found in group II of the periodic table, all the Alkaline Earth metals have two electrons in their outermost shell. Losing both electrons to other non-metal atoms completely empties their outer shell making the ion of the atom stable. Position of the Alkaline Earth metals

Physical properties of the Alkaline Earth metals two The group II elements, the Alkaline Earth metals are all reactive metals (except beryllium), able to form ionic compounds with non-metals like chlorine. They have similar physical and chemical properties. They have a typically s_______ metallic appearance when freshly cut, but all tarnish with time. They all have to be stored under oil (except beryllium and magnesium) so they don’t react with either o_________ or water vapour. Like all metals, they are good conductors of heat and electricity, but they have relatively low melting and boiling points. Physical properties of group II Alkaline Earth metals: 2,2 2,8,2 Be Mg Ca 2,8,8,2 Sr 2,8,8,18,2 Science Interactive LTD Copyright 2005 Word bank: shiny oxygen All except beryllium and magnesium are reactive, are able to tarnish in air and have to be stored under oil. All form ions carrying +2 charge. Mg 2+ , Ca 2+ . All react with non-metals to form ionic salts with similar formulae (CaCl 2 & MgCl 2 ) Magnesium and beryllium are used because of their high strength to weight ratio. The calcium ion (Ca 2+ ) is extremely important for teeth and bone formation. Shared group II properties. Strontium Calcium Atom Formula Electron configuration Magnesium Beryllium Element Symbol

Properties and uses of beryllium Beryllium is a shiny, silver and un-reactive metal with a very high strength to weight ratio. Beryllium is the least reactive group II metal. Beryllium is very expensive because, like gold it is rare. This metal is used to build s________ and aircraft parts because it is so light and strong. The cost of beryllium is over £10,000 per kilogram. Unlike other Alkaline Earth metals, beryllium does not readily react with oxygen, w_______ or laboratory acids. Beryllium gives a blue flame when combusted in oxygen Give a definition of an ionic and covalent compound ? Properties and uses of beryllium: Science Interactive LTD Copyright 2005 Word bank: satellite water Satellites Metallic structure Beryllium is the least reactive group II Alkaline Earth metal. Beryllium does not easily form ionic compounds with other non metals. Beryllium is an extremely light and strong metal and is used in the satellite industry. This is to save weight. It is also very costly at over £10,000 per kilogram. This is because it is very rare. Beryllium in emeralds Beryllium is a shiny silver metal, with an extremely high strength to weight ratio. Atoms are held in a metallic structure. Beryllium is a good conductor of heat and electricity. The symbol of beryllium is Be. Beryllium

Properties and uses of magnesium Magnesium is a shiny, hard and moderately reactive metal. Magnesium is the second least reactive group II metal. Magnesium can be used as a metal for the manufacture of lightweight car components and b_______ frames. Magnesium is an extremely light and strong metal. Magnesium was also used in incendiary bombs which caused widespread damage to German cities in WWII. Magnesium carbonate is used as an i___________ remedy as it neutralises excessive stomach acid. Magnesium gives an white flame when combusted in oxygen. Properties and uses of magnesium: Science Interactive LTD Copyright 2005 Word bank: bike indigestion Magnesium frames Metallic structure Magnesium is the second most reactive group II Alkaline Earth metal. Magnesium is used to build lightweight components for the car industry as well as bike frames. Powdered magnesium will readily combust giving an intense white flame. Magnesium incendiary bombs were dropped on Germany during the second World war. Incendiary bombs Magnesium is a shiny silver metal, with an moderately high strength to weight ratio. Atoms are held in a metallic structure. Magnesium is a good conductor of heat and electricity. The symbol of Magnesium is Mg. Magnesium

Properties and uses of calcium Calcium is a shiny, soft and reactive metal. Calcium is the third most reactive group II metal. Calcium compounds are found in a wide range of chemicals or uses including calcium carbonate which is used by all mammals to build b_______ and teeth. Calcium carbonate is also the main mineral found in three types of rock, marble, chalk and limestone. Milk and dairy products are very rich in the calcium ion, Ca +2 . Calcium gives a reddish o_________ flame when combusted in oxygen. Properties and uses of calcium: Science Interactive LTD Copyright 2005 Word bank: bones orange Metallic structure Calcium is the third most reactive group II Alkaline Earth metal. It is available in schools and needs to kept under oil in a locked metal cabinet. Calcium is used by humans in calcium carbonate to build teeth and bones. Calcium found in calcium carbonate is also found in three rocks types named marble, limestone and chalk. Marble (CaCO 3 ) Milk Calcium is a shiny grey metal with a low strength to weight ratio. Most calcium is found in calcium carbonate. Atoms are held in a metallic structure. Calcium is a good conductor of heat and electricity. The symbol of calcium is Ca. Calcium

Properties and uses of strontium Strontium is a shiny, silver, soft and reactive metal. Strontium is the most r________ group II metal. Strontium compounds are found in a wide range of chemicals or uses including those that give a vibrant r____ colour to fireworks. It is so reactive that schools cannot have a sample in their laboratories. It is kept in sealed vials to prevent it making contact with oxygen or water. Strontium gives a strong red flame when combusted in oxygen. Properties and uses of strontium: Science Interactive LTD Copyright 2005 Word bank: reactive red Sr 38 Metallic structure Strontium is the most reactive and dangerous of the group II Alkaline Earth metals. It is so reactive that schools cannot have samples in their laboratories. It is kept in sealed vials to prevent it making contact with oxygen or water. Strontium compounds are used in fireworks like the ones used on bonfire night to give a bright red colour. Strontium in fireworks Strontium is a shiny grey metal and is the most reactive Alkaline Earth metal. Atoms are held in a metallic structure. Strontium is a good conductor of heat and electricity. The symbol of strontium is Sr. Strontium

Detecting the presence of group II metal compounds When compounds like magnesium oxide or calcium chloride are heated in a gas flame they give a characteristic colour. We can take a c__________ and identify which group II metal is found present in the compound by its colour and l_______ spectrum. For example strontium in strontium chloride gives a distinctive red colour in a blue gas flame. Give the colour of copper and magnesium in oxygen ? Metal flame tests: Science Interactive LTD Copyright 2005 Word bank: compound light When combusted in oxygen, strontium gives a characteristic red flame. When combusted in oxygen, calcium gives a characteristic red - orange flame. When combusted in oxygen, magnesium gives a characteristic white flame. When combusted in oxygen, beryllium gives a characteristic blue flame. Notes Calcium Strontium Spectrum Flame test Metal Beryllium Magnesium

Group II metals with the halogens Calcium Chlorine Group Example one Example two Aluminium + Chlorine Calcium Chloride ( CaCl 2 ) Magnesium Fluorine Magnesium Fluoride ( MgF 2 ) x2 x2 All the elements found in group II (except beryllium) can readily form metal halide compounds with the halogens. During the reaction, group II metals lose two electrons to the halogen atoms. This group of ionic compounds includes magnesium fluoride. They are mostly soluble white crystalline solids. Group II metals with the halogens: Science Interactive LTD Copyright 2005 Mg (s) + F 2 (g) MgF 2 (s) Example

Group II metals with oxygen Magnesium Oxygen Group Aluminium + Chlorine Magnesium Oxide ( MgO ) O 2 Calcium Oxygen Calcium Oxide ( CaO ) Example one Example two All the elements found in group II (except beryllium) can readily form metal oxides with the oxygen. During the reaction group II metals lose two electrons to oxygen atoms. This group of ionic compounds includes calcium oxide. They are mostly soluble, white crystalline solids. Group II metals with oxygen: Science Interactive LTD Copyright 2005 2Ca (s) + O 2 (g) 2CaO (s) Example

Group II metals with water Magnesium Water Group Aluminium + Chlorine H 2 0 Calcium hydroxide Ca(OH) 2 Calcium Water Magnesium hydroxide Mg(OH ) 2 x2 x2 Example one Example two All the elements found in group II (except beryllium and magnesium) can readily form metal hydroxides with the water molecule. During the reaction, group II metals lose two electrons to the forming hydroxide ion. This group of ionic compounds includes magnesium hydroxide. They are mostly soluble, white crystalline solids. Group II metals with water: Mg (s) + 2H 2 O (g) Mg(OH) 2 (aq) + H 2 (g) Example Science Interactive LTD Copyright 2005

Reactivity of the group II metals The Alkaline Earth metals become more reactive as you descend the group, for example reactions between beryllium and oxygen or water do not occur at room temperature. Reactions with m___________ and calcium with oxygen or water are moderately fast. Reactions between strontium and oxygen or water are very violent. The reason why c_________ and strontium are the most reactive group II metals is because, as the size of the atom increases, less energy is required to lose the outer two electrons, during the formation of ionic compounds. Reactivity in group II metals: Beryllium Magnesium Calcium Strontium Beryllium reacts not at all with oxygen, water or HCl acid. Displaced from its compounds by Mg, Ca & Sr. Behaviour of elements with oxygen, water and acid. Displacement from their compounds. All the metals from group II are extracted from their ionic compounds using electrolysis. Unlike iron and copper, they cannot be displaced from their ores using carbon displacement. Magnesium reacts with (on heating) oxygen and steam, and with cold HCl acid. Displaced from its compounds by Ca & Sr. Calcium reacts with (on heating) oxygen and with cold water and HCl acid Displaced from its compounds by Sr. Strontium reacts readily with oxygen and with cold water and HCl acid Not displaced from its compounds. Science Interactive LTD Copyright 2005 Word bank: magneisum calcium Reactivity of the group II Alkaline Earth metals Reactivity

Properties of group II ionic compounds Ionic compounds of the group II metals are moderately alkaline . Based on the chemistry of their ionic bonds, these compounds all have similar properties. Mostly, they are moderately soluble in water and have a crystalline structure under the microscope. Group II ionic compounds, like calcium carbonate are w_______ in colour. They also conduct electricity when molten or in solution. They also have very high melting points, for example magnesium oxide lines the inside of pottery kilns that operate at very high temperatures (2000 o C) Properties of group II ionic compounds: Science Interactive LTD Copyright 2005 Word bank: white Property five Property four Property one : Some ionic compounds are very coloured. Most of the ionic compounds of group II metals are white in colour. Property two : They form regular crystals and appear like mini diamonds under the microscope. Property three : They have very high melting and boiling points due to the very strong forces of attraction between the ions. Property four : When molten or in ionic solutions, group II ionic compounds like magnesium chloride can conduct electricity. Property five : They are only moderately soluble in water. Property one Property two Property three

Rules for group II ionic compounds There are several rules that help you to understand what happens to the atoms and their e_________ during the formation of group II ionic compounds. Remember for atoms to be stable, they either need to lose or gain electrons to empty or fill their outer shells therefore having the same electronic configuration as the Noble gases . Ions of atoms are very stable and once formed, do not easily revert back to their atomic electronic configuration. That’s why we have so many compounds and very few e_________ found in their natural state. Group II ionic compounds and their rules: Ionic Bond Science Interactive LTD Copyright 2005 Word bank: electrons elements Rule four and five Rule One : Ionic compounds contains a metal and non-metal. Rule two : Group II metals always lose two electrons forming a + 2 positive ion. Rule three : Non-metals always gain these electron forming negative ions. Rule four : The attraction between the positive and negative ions is the ionic bond. Rule five : The overall charge of any ionic compound containing a metal and non metal ion must always equal zero. Rule one Rule two Rule three

Calcium carbonate Calcium is not found in its pure state, but usually in calcium carbonate (CaCO 3 ) This ionic compound has a very low solubility and has a wide number of uses in the human b______. In addition to forming bones and teeth, calcium carbonate is the mineral found in three rock types: c________, limestone and marble. These three rock types are widely used as building materials. Uses of calcium carbonate: Science Interactive LTD Copyright 2005 Word bank: bone chalk Calcium carbonate (CaCO 3 ) is found in bones, teeth, shells and rocks. It is a ionic compound which is only slightly soluble. When biological tissues concentrates calcium carbonate, it comes out of solution and builds shells, teeth and bones. Both limestone and marble is used in the building industry for many uses including the manufacture of statues, kitchen and bathroom surfaces. Calcium carbonate is also heated to form calcium oxide (CaO). This is known as quicklime which is the starting material for making cement and concrete. CaCO 3 in limestone CaCO 3 in chalk CaCO 3 in marble CaCO 3 in bones CaCO 3 in teeth CaCO 3 in shells

1: Define the following terms: Metals, Elements, Ionic-compound, Ion & Ionic-bond. 2: Look at the three pictures below. Complete the table. 3: Answer the following: a) Why are the group II metals known as the alkaline Earth metals. b) Beryllium has this chemical symbol; What does all this information mean. c) Draw an atom of Beryllium from the information given. d) In part c you drew an atom of Beryllium, now label the protons, electrons and neutrons. e) Name three compounds in which an alkaline earth metal can lose two electrons to form an ion. f) Give five properties of all metals. How do the chemical and physical properties of the alkaline Earth metals differ from an average transitional metal like copper, gold or iron. g) All the alkaline Earth metals have a metallic structure, explain this term. Extension questions and homework 9 Be 4 Science Interactive LTD Copyright 2005 Physical properties and uses Strontium Three Beryllium Two Magnesium One Element Picture

4: Complete the following table. 5: Answer the following questions: a) The chemical reactivity of the Alkaline Earth metals increases as you go down the group explain this. b) The boiling and melting points of the Alkaline Earth metals decrease as you go down the group. Explain why. 6: Complete the following table. Name the salts formed during the following reactions. 7: Draw a dot and cross diagram for CaI 2 , Ca(OH) 2 & MgCl 2 Internet: Go to google.co.uk and find out the use of calcium oxide, calcium hydroxide and calcium carbonate. Which one is also known as ‘quicklime.’ x2 Science Interactive LTD Copyright 2005 Calcium Solid Magnesium 2 Beryllium Symbol Colour State at room temperature Electrons in outer shell Group II metal Salt Calcium oxide Salt Strontium + Oxygen Beryllium + Fluorine Calcium + Water Reactants Magnesium + Oxygen BeF 2 Calcium + Oxygen Magnesium + Chlorine Formula Formula Reactants MgCl 2 Ca(OH) 2 CaI 2