Unit 17 The Alkaline Metals

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Unit 17

The Alkaline Metals

The physical and chemical properties of the group I elements, the alkaline metals.

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

Their reactions and compounds with oxygen.

Their reactions and compounds with water.

Their reactions and compounds with the halogens.

That their reactivity increases as you descend the group.

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

That the electrolysis of sodium chloride yields sodium metal and chlorine gas.

Alkaline, Metals, Lithium, Sodium, Potassium, Rubidium, Caesium, Physical, Chemical, Properties, Ionic, Compounds, Non metals, Ions, Reactions, Oxides, Hydroxide, Halides, Atoms, Chemical, Bond & Reactivity. Unit 17: The Alkaline 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 metals one Group I of the periodic table contains a family of very reactive metals known as the alkaline metals. This group of e________ contains lithium, sodium, potassium and rubidium. They are not found in their pure state like gold, but are found tied up in ionic compounds. These metal elements have relatively low melting or boiling points and densities, when compared to transitional m______ like copper, iron and titanium. Name two compounds that contain sodium and potassium ? The alkaline metals: Science Interactive LTD Copyright 2005 Word bank: elements metals The alkaline metals have similar chemical properties because they all have one electron in their outer shell. Their reactivity and atom size (radius) increases as you descend the group from lithium to rubidium. Their melting and boiling points rise as you descend the group. The alkaline metals Notes Diagram Found in group I of the periodic table, all the alkaline metals have one electron in their outermost shell. Losing this single electron to other non-metal atoms completely empties their outer shell making the ion of the atom stable. Position of the alkaline metals

Physical properties of the alkaline metals two The group I elements, the alkaline metals are all reactive metals able to form ionic compounds with other non-metals like chlorine. They have similar p_______ and chemical properties. They all have a typical shiny metallic appearance when freshly cut, but all tarnish within minutes of contact with air. They all have to be stored under o____ so they don’t react with either oxygen or water vapour. Like all metals, they are good conductors of heat and electricity, but they have low melting and boiling points. Give a definition of an ionic and covalent compound ? Physical properties of group I alkaline metals: 2,1 2,8,1 Li Na K 2,8,8,1 Rb 2,8,8,18,1 Science Interactive LTD Copyright 2005 Word bank: physical oil All are reactive metals, tarnish in air and have to be stored under oil. All form ions carrying a +1 plus charge Li + , Na + , K + All are less dense than water and react vigorously to form hydroxides with alkaline pHs. All react with non-metals to form ionic salts with similar formulas (e.g. Lithium chloride LiCl) All are soft and can be cut with a knife. Shared group I properties Rubidium Potassium Atom Formula Electron configuration Sodium Lithium Element Symbol

Properties and uses of lithium Lithium is a shiny soft reactive metal. Lithium is the least reactive group I metal. Lithium compounds are found in a wide range of uses including long life batteries, similar to those used in pacemakers. Lithium is also used in psychiatric drugs to control the behaviour of patients suffering from aggressive psychosis. Lithium reacts readily with o_______, water and acid forming ionic salt compounds which are white, alkaline and highly soluble. Lithium gives a r____ flame when combusted in oxygen Find out about other uses of lithium or its compounds ? Properties and uses of lithium: Science Interactive LTD Copyright 2005 Word bank: oxygen red Anti psychotic drugs Metallic structure Lithium is the least reactive group I alkaline metal. Lithium compounds have many uses including batteries found in mobile phones, calculators and heart pacemakers. Lithium is also used as an antipsychotic drug. It has an effect in the human body to lower the activity of the brain and is often called a chemical straightjacket. Lithium batteries Lithium is a shiny silver metal, which is easy to cut with a low density. Atoms are held in a metallic structure. Lithium is a good conductor of heat and electricity. The symbol of lithium is Li. Lithium

Properties and uses of sodium Sodium is a shiny soft reactive metal. Sodium is the second least reactive group I metal. Sodium compounds are found in a wide range of chemicals or uses including sodium found in table s_____ or sodium chloride. It is also used in ‘sodium vapour lights’ found in street lighting. Sodium reacts readily with oxygen, water and acid forming ionic salt compounds which are white, alkaline and highly soluble. Sodium gives an o_______ flame when combusted in oxygen. Find out about other uses of sodium or its compounds ? Properties and uses of sodium: Science Interactive LTD Copyright 2005 Word bank: salt orange Sodium in sodium chloride Metallic structure Sodium is the second most reactive group I alkaline metal. Sodium is used in sodium vapour lights. This characteristic orange light helps light our streets at night. Sodium is also found in table salt or sodium chloride. Too much salt in our diets will lead to high blood pressure and the increased risk of cardiovascular disease. Sodium vapour lamps Sodium is a shiny silver metal, which is easy to cut with a low density. Atoms are held in a metallic structure. Sodium is a good conductor of heat and electricity. The symbol of sodium is Na. Sodium

Properties and uses of potassium Potassium is a shiny soft reactive metal. Potassium is the third most reactive group I metal. Potassium compounds are found in a wide range of chemicals or uses including soluble potassium ions essential for healthy p______ growth. Potassium reacts readily with oxygen, water and acid forming ionic salt compounds which are white, alkaline and highly soluble. Potassium gives a l_______ flame when combusted in oxygen. Find out about other uses of potassium or its compounds ? Properties and uses of potassium: Science Interactive LTD Copyright 2005 Word bank: plant lilac Metallic structure Potassium is the third most reactive group I alkaline metal. It is available in schools and needs to kept under oil in a locked metal cabinet. Potassium is found in fertilisers, and is used by plants for healthy growth. Without potassium, plants would have yellow leaves and stunted growth. Bananas are also rich in potassium and are good for you. Potassium in fertilisers Potassium in bananas Potassium is a shiny silver metal, which is easy to cut with a low density. Atoms are held in a metallic structure. Potassium is a good conductor of heat and electricity. The symbol of potassium is K. Potassium

Properties and uses of rubidium Rubidium is a shiny silver soft reactive metal. Rubidium is the most reactive and dangerous group I metal. It is so reactive that schools cannot use it in their laboratories. Rubidium compounds are found in a wide range of chemicals or uses including rubidium used in psychiatric drugs to control the behaviour of patients suffering from aggressive psychosis. Find out about any other uses of rubidium ? Properties and uses of rubidium: Science Interactive LTD Copyright 2005 Metallic structure Rubidium is the most reactive and dangerous of the group I alkaline metals. It is so reactive that schools cannot use it in their laboratories. It is kept in sealed vials to prevent it making contact with oxygen or water. Rubidium, like lithium is found in strong sedative drugs like valium and librium. These drugs have a sedative effect on the patient, reducing anxiety and stress. Mental illness in Humans Sedative Drugs and rubidium Rubidium is a shiny metal which is a liquid at room temperature. Atoms are held in a metallic structure. Rubidium is a good conductor of heat and electricity. The symbol for rubidium is Rb. Rubidium

Detecting the presence of group I metal compounds When compounds like sodium chloride are heated in a gas flame they give a characteristic colour. We can take a compound and identify which group I metal the compound contains by its colour and light spectrum. For example sodium in sodium chloride gives a distinctive orange colour in a blue gas flame. Give the colour of copper and magnesium in oxygen ? Metal flame tests: Science Interactive LTD Copyright 2005 When combusted in oxygen, rubidium gives a characteristic red -orange flame. When combusted in oxygen, lithium gives a characteristic deep red flame. When combusted in oxygen, sodium gives a characteristic orange flame. When combusted in oxygen, potassium gives a characteristic lilac flame. Notes Lithium Rubidium Spectrum Flame test Metal Potassium Sodium

Group I alkaline metals with oxygen Lithium Oxygen Group Aluminium + Chlorine O 2 Example one Example two Lithium oxide ( Li 2 O ) Sodium Oxygen Sodium Oxide ( Na 2 O ) x2 x2 All the elements found in group I can readily form metal oxides with the element oxygen. During the reaction, group I metals lose one electron to oxygen. This group of ionic compounds includes sodium oxide. The group I oxides are all soluble and mostly white crystalline solids. Group I metals with oxygen: Science Interactive LTD Copyright 2005 4Na (s) + O 2 (g) 2Na 2 O (s) Example

Group I alkaline metals with water Group Aluminium + Chlorine Potassium hydroxide ( KOH ) H 2 0 Lithium Water Example one Example two Potassium Water Lithium hydroxide ( LiOH ) All the elements found in group I can readily form metal hydroxides with the water molecule. During the reaction, group I metals lose one electron to the forming hydroxide ion. This group of ionic compounds includes sodium hydroxide. The group I hydroxides are all soluble and mostly white crystalline solids. Group I metals with water: 2Na (s) + 2H 2 O (g) 2NaOH (aq) + H 2 (g) Example Science Interactive LTD Copyright 2005

Reactivity of the group I metals The alkaline metals become more reactive as you descend the group, for example reactions between sodium and lithium with oxygen or water are moderately fast. Reactions with potassium and oxygen or water are very fast. Reactions between rubidium and oxygen or water are explosive. The reason why rubidium is the most reactive group I metal is because, as the size of the atom increases, less energy is required to lose the outer electron during the formation of ionic compounds. What's the rule for the group VII elements, the halogens ? Reactivity in metals: Lithium Sodium Potassium Rubidium All the alkaline metals from group I are extracted from their ionic compounds using electrolysis. Unlike iron and copper they cannot be displaced from their ores using carbon. Behaviour of elements with oxygen, water and acid. Displacement from their compounds. Lithium reacts with (on heating) oxygen, cold water and HCl acid (moderately fast.) Displaced from its compounds by Na, K & Rb. Sodium reacts with (on heating) oxygen and cold water and HCl acid (very fast.) Displaced from its compounds by K & Rb. Potassium reacts with (on heating) oxygen and with cold water and HCl acid (Violent) Displaced from its compounds by Rb. Rubidium reacts with (on heating) oxygen and with cold water and HCl acid (Explosive) Not displaced from its compounds. Science Interactive LTD Copyright 2005 Reactivity of the group I alkaline metals Reactivity

Properties of group I ionic compounds Ionic compounds of the group I metals are all strongly alkaline . Based on the chemistry of their ionic bond, these compounds have similar properties. Mostly, they are highly soluble in water and have a crystalline structure under the m__________. Group I ionic compounds like sodium chloride are white in colour. They also conduct electricity when molten or in solution. They also have very high m__________ points, for example sodium chloride becomes molten at temperatures in excess of 1000 o C. General properties of ionic compounds: Science Interactive LTD Copyright 2005 Word bank: microscope melting Property five Property four Property one : The majority of group I ionic compounds are white in colour. Some ionic compounds are coloured, for example copper sulphate is a deep blue 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, ionic compounds can conduct electricity. Property five : They are highly soluble in water. Property one Property two Property three

Group I metal halide compounds All the elements found in group I can form metal halide compounds with the halogens. During the reaction, group I metals lose one electron to the halogen element. This group of ionic compounds includes sodium chloride. They are all soluble and mostly white crystalline solids. Draw a dot and cross diagram for NaI. Group I metals with the halogens: Group Aluminium + Chlorine Lithium Chlorine Lithium Chloride ( LiCl ) Potassium bromine Potassium bromide ( KBr ) Example one Example two Science Interactive LTD Copyright 2005 2Li (s) + Cl 2 (g) 2LiCl (s) Example

Rules for group I ionic compounds There are several rules, that help you to understand what happens to the atoms and their electrons during the formation of group I ionic compounds. Remember for atoms to be stable, they either need to lose of gain electrons to empty or f____ 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 a________ electronic configuration. That’s why we have so many compounds and very few elements found in their natural state. Group I ionic compounds and their rules: Science Interactive LTD Copyright 2005 Word bank: fill atomic Rule four and five Rule One : Ionic compounds contains a metal and non-metal. Rule two : Group I metals always lose one electron forming a + 1 positive ion. Rule three : Non metals always gain this electron forming negative ions. Rule four : The attraction between the positive and negative ions is the ionic bond. Rule five : The overall charge of an ionic compound must always equal zero. Rule one Rule two Rule three

Building ionic crystals Ions of atoms build crystals. The structure extends itself in all directions giving the crystal with a regular arrangement of ions called a l________. For sodium chloride, the ions arrange themselves alternatively in all three dimensions. This give sodium chloride crystals a c_______ shape. All ionic solids have similar ionic structure to sodium chloride. Did you know you can grow your own crystals using a small seed crystal and a saturated ionic solution...it takes about a week ! Ionic crystals: Science Interactive LTD Copyright 2005 Word bank: lattice cubic Crystal structure Diagram Diagram Sodium chloride : Ions of sodium and chlorine have opposite charges. Simple unit : The attraction between the sodium ion and the chloride ions form a single unit. Ions begin to build 3-D shapes in a regular shape. Crystal structure : Thousands of ions arrange alternatively to form salt crystals. Sodium chloride Simple unit

Electrolysis of brine sodium chloride Chlorine and its compounds are used in huge quantities around the world. Chlorine is extracted from sodium chloride using electrolysis. During e____________, the sodium ion regains its single electron forming the metal sodium. Conversely, the chloride ion loses its electron to form molecular chlorine gas which is then captured at the anode. Equation: Cathode: 2Na + + 2e - 2Na Anode: 2Cl - Cl 2 + 2e - Electrolysis of sodium chloride: Science Interactive LTD Copyright 2005 Word bank: electrolysis What happens during the electrolysis of sodium chloride Concentrated sodium chloride or brine is added to the electrolysis cell. This is heated and allowed to become molten. The current is then switched on and electrolysis starts. Electrolysis of sodium chloride Chloride (Cl-) ions when molten are free to move. The chloride ions being negatively charged travel to the positive anode. Chloride ions (Cl - ) lose their electron and form diatomic chlorine (Cl 2. ) Chlorine is then used as a gas. Sodium (Na + ) ions when molten are free to move. The sodium ions being positively charged travel to the negative cathode and regain their lost electron. Molten sodium is formed at the cathode. Anode (+ve) Cathode (-ve)

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 I metals known as the alkaline metals. b) Sodium has this chemical symbol; What does all this information mean. c) Draw an atom of sodium from the information given. d) In part C, you drew an atom of sodium, now label the protons, electrons and neutrons. e) Name three compounds in which an alkaline metal can lose an electron to form an ion. f) Give five properties of all metals. How do the chemical and physical properties of the alkaline metals differ from an average transitional metal like copper, gold or iron. g) All the alkaline metals have a metallic structure, explain this term. Extension questions and homework 23 Na 11 Science Interactive LTD Copyright 2005 Physical properties of metals and their main uses Potassium Three Sodium Two Lithium One Element Picture

4: Complete the following table. 5: Answer the following questions: a) The chemical reactivity of the alkaline metals increases as you go down the group: Explain why. b) The boiling and melting points of the alkaline 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 LiI, NaOH & Na 2 O Internet: Go to google.co.uk and find out the use of sodium hydroxide and sodium chloride. How do they extract sodium chloride from the brine pits found in Cheshire. Science Interactive LTD Copyright 2005 Potassium Solid Sodium Li 1 Lithium Symbol Colour State at room temperature Electrons in outer shell Group I metal Salt Sodium hydroxide Salt Potassium + Water Sodium + Chlorine Lithium + Fluorine Reactants Potassium + Chlorine NaCl Sodium + Water Lithium + Chlorine Formula Formula Reactants Na 2 O NaOH LiI