ALKALI METALS.pptx

alkali metals - periodic table

1. DIGITAL ALBUM on ALKALI METALS Presented By Sreelakshmi A 1 st Year B.Ed Physical Science GCTE Trivandrum

2. The Periodic Table The periodic table of elements, is a tabular display of the chemical elements, which are arranged by atomic number, electron configuration, and recurring chemical properties.

3. GROUP 1 ELEMENTS The   GROUP 1 ELEMENTS  in the periodic table are known as the  ALKALI METALS. They are Lithium (Li) Sodium(Na) Potassium(K) Rubidium( Rb ) Caesium (Cs) Francium(Fr)

4. ALKALI METALS

5. Alkali metals??? These   metals  are  called alkali metals  because they form strong alkaline hydroxides(basic in nature) when react with water. Examples NaOH KOH LiOH

6. Electronic Configuration The general electronic configuration of Group 1 elements is ns 1 . They have a strong tendency to donate their valence electron in the last shell to form strong ionic bonds.

7. PROPERTIES In order to prevent the elements from coming in contact with oxygen, they are stored in jars that contain oil . They display a very low level of density of up to 1 gcm -3  which means that they can easily float on the surface of the water . The melting points of these elements are quite low, which is 180° Celsius in the case of Lithium, while it is 39° Celsius in the case of Rubidium.

8. Change of atomic radius In alkali metals, the atomic radius increases down the group. Each element has 1 electron in each outer shell because they are all in group 1. Reactivity The alkali metals are very reactive, but they are not found in elemental forms in nature. The elements are usually  found  in mineral oil, or paraffin oil. Alkali metals are mostly soft silver-colored, of low density .

9. Abundance on earth All of the alkali metals are found in nature, but not in their pure forms. Most combine with oxygen and silica to form minerals in Earth, and have to get separated from the substance that they’re combined with. Alkali metals are soft silver-colored, with low density and can explode when combined with water.

10. Change of boiling point and melting point All alkali metals are very soft and they have low melting and boiling points. Alkali metals melting and boiling points decrease down the group, so which means that Lithium has a lower boiling and melting point than Francium. As you go down, the alkali metals, the melting and boiling points get lower.

11. Uses Of Alkali Metals Lithium is used to produce ceramics and glasses. Devices that require batteries, for example  mobiles or computers contain Lithium batteries. Sodium is used to produce salt , in the form of sodium chloride. Sodium hydroxide is used to clean ovens. Cesium is use to produce  military aircrafts. A compound of rubidium, silver and iodine, is used to make film batteries. Francium doesn’t have many uses, but it’s used in laboratories for experiments, and needs to be handled carefully, because it’s toxic.

12. Picture window ALKALI METALS

13. Lithium ( Li ) Atomic Weight  6.94 Density  0.535 g/cm 3 Melting Point  180.54 °C Boiling Point  1342 °C

14. Discovery date 1817  Discovered by Johan August Arfvedson   Origin of the name The name is derived from the Greek ' lithos ' meaning stone.  Key isotopes 7 Li 

15. Electronic configuration

16. PROPERTIES The lightest metal Lithium easily floats on water Lithium reacts with water releases hydrogen gas. It's soft enough to cut with hand shears, leaving marks such as you see on this sample.

17. USES OF LITHIUM Lithium is often used in batteries, and lithium oxide can help process silica.  Lithium can also be used to make lubricating greases, air treatment, and aluminum production. Lithium is used for mental illnesses, including bipolar disorder, depression, and schizophrenia.

18.  Photo sensitive glass from lithium-silicate family of glasses Larger lithium battery.

19. Sodium ( Na ) Atomic Weight  22.98976928 Density  0.968 g/cm 3 Melting Point  97.72 °C Boiling Point  883 °C

20. Discovery date 1807  Discovered by Humphry Davy  Origin of the name The name is derived from the English word 'soda'.  Key isotopes 23 Na 

21. Electronic configuration

22. PROPERTIES These soft. Silvery sodium chunks were cut with a knife and stored under oil. In air they turn white in seconds. When exposed to water they generate hydrogen gas and explode in flaming balls of molten sodium

23. USES OF SODIUM Pure sodium has many applications, including use in sodium-vapor lamps which produce very efficient light. Sodium is used as a heat exchanger in some nuclear reactors, and as a reagent in the chemicals industry. But sodium salts have more uses than the metal itself. The most common compound of sodium is sodium chloride (common salt). Sodium carbonate (washing soda) is also a useful sodium salt. It is used as a water softener.

24. Sodium carbonate , Na 2 CO 3 , ( awashing soda Sodium chloride (salt) Sodium vapour lamb

25. BIOLOGICAL ROLE Sodium is essential to all living things Our bodies contain about 100 grams, but we are constantly losing sodium in different ways so we need to replace it. We can get all the sodium we need from our food, without adding any extra. The average person eats about 10 grams of salt a day, but all we really need is about 3 grams. Any extra sodium may contribute to high blood pressure.. Sodium is important for many different functions of the human body. For example, it helps cells to transmit nerve signals and regulate water levels in tissues and blood.

26. Potassium (K) Atomic Weight  39.0983 Density  0.856 g/cm 3 Melting Point  63.38 °C Boiling Point  759 °C

27. Electronic configuration

28. PROPERTIES The purple tint on these soft potassium cubes is a very thin oxide coating. Exposed to air they turn black in seconds. Exposed to water they would explode, sending off characteristic purple-red flaming drops.

29. USES OF POTASSIUM Potassium  is important for plant growth. Industrial applications for  potassium  include soaps, detergents, gold mining, dyes, glass production, gunpowder, and batteries. The greatest demand for potassium compounds is in fertilizers. Potassium salts are of great importance, including the nitrate, carbonate, chloride, bromide, cyanide and sulfate. Potassium carbonate is used in the manufacture of glass. Potassium hydroxide is used to make detergent and liquid soap. Potassium chloride is used in pharmaceuticals and saline drips.

30. . Potassium based fertilizer Potassium hydroxide is used for Making soap

31. BIOLOGICAL ROLES Potassium is essential to life. Potassium ions are found in all cells. It is important for maintaining fluid and electrolyte balance. Plant cells are particularly rich in potassium, which they get from the soil. Agricultural land, from which harvests are taken every year, needs to have its potassium replenished by adding potassium-based fertilisers . The average human consumes up to 7 grams of potassium a day, and stores about 140 grams in the body cells. A normal healthy diet contains enough potassium, but some foods such as instant coffee, sardines, nuts, raisins, potatoes and chocolate have above average potassium content. The naturally occurring isotope potassium-40 is radioactive and, although this radioactivity is mild, it may be one natural cause of genetic mutation in humans.

32. RUBIDIUM ( Rb Atomic Weight  85.4678 Density  1.532 g/cm 3 Melting Point  39.31 °C Boiling Point  688 °C

33. Discovery date 1861  Discovered by Gustav Kirchhoff and Robert Bunsen  Origin of the name The name is derived form the Latin ' rubidius ', meaning deepest red.  Key isotopes 85 Rb,  87 Rb 

34. Electronic Configuration

35. PROPERTIES This ampoule contains a gram of highly reactive rubidium metal . Broken open it would catch fire rapidly. Rubidium is commonly used in cheaper atomic clocks (the most accurate ones use cesium).

36. USES OF RUBIDIUM Rubidium is little used outside research. It has been used as a component of photocells, to remove traces of oxygen from vacuum tubes and to make special types of glass. It is easily ionised so was considered for use in ion engines, but was found to be less effective than caesium . It has also been proposed for use as a working fluid for vapour turbines and in thermoelectric generators. Rubidium nitrate is sometimes used in fireworks to give them a purple colour . Rubidium carbonate is applied in glass lenses built in night vision devices.

37. BIOLOGICAL ROLE Rubidium has no known biological role and is non-toxic. However, because of its chemical similarity to potassium we absorb it from our food, and the average person has stores of about half a gram. It is slightly radioactive and so has been used to locate brain tumours , as it collects in tumours but not in normal tissue.

38. Ceasium (Cs) Atomic Weight  132.90545196 Density  1.879 g/cm 3 Melting Point  28.44 °C Boiling Point  671 °C

39. Discovery date 1860  Discovered by Gustav Kirchhoff and Robert Bunsen  Origin of the name The name comes from the Latin 'caesius', meaning sky blue, and derived from its flame colour.  Key isotopes 133 Cs 

40. Electronic Configuration

41. PROPERTIES The cesium in this ampoule melts if you hold it in your hand for a minute, yielding the prettiest liquid gold. If the ampoule were to break in your hand, the resulting explosion would be extremely unpleasant.

42. USES OF CAESIUM The most common use for caesium compounds is as a drilling fluid. They are also used to make special optical glass, as a catalyst promoter, in vacuum tubes and in radiation monitoring equipment. One of its most important uses is in the ‘ caesium clock’ (atomic clock). These clocks are a vital part of the internetand mobile phone networks, as well as Global Positioning System (GPS) satellites. They give the standard measure of time: the electron resonance frequency of the caesium atom is 9,192,631,770 cycles per second. Some caesium clocks are accurate to 1 second in 15 million years.

43. A caesium   atomic fountain  used as part of an  atomic clock Caesium   formate used as a drilling and completion fluid. Autoradiograph of radioactive cesium particle .

44. Francium (Fr) Atomic Weight  223 Density  Unknown Melting Point   21°C Boiling Point   650°C

45. Discovery date 1939  Discovered by Marguerite Perey  Origin of the name Francium is named after France.  Key isotopes 223 Fr 

46. Electronic Configuration

47. PROPERTIES Uranium and thorium minerals produce francium in vanishingly small quantities via their natural radioisotope decay chains. At most a few atoms at a time exist in a rock like this, and you can't see any of them . Francium has no uses, having a half life of only 22 minutes. Francium has no known biological role. It is toxic due to its radioactivity.