The Alkali Metals

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The Alkali Metals

• Group - 1 / A

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Agenda

• Introduction
• Lithium (Li)
• Sodium (Na)
• Potassium (K)
• Rubidium (Rb)
• Caesium (Cs)
• Francium (Fr)

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Introduction

• The elements of 1st A group are all solid but
  soft at room temperature
• All are shiny metals that have to be kept under
  oil or in inert atmospheres because they are very
  reactive
• With the exception of the radio active and
  extremely rare Francium, these shiny metals react
  rapidly with oxygen in the air, so that their
  surfaces quickly become dull.
• Caesium is the most chemically reactive of all
  the elements in this group, and spontaneously
  catches fire in air.

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Introduction cont.

• The atoms of this elements all have just one
  electron in there outer shell this is why they
  are so reactive.
• All group-1 elements react violently in water
  displacing hydrogen ions to produce hydrogen gas
  (H), leaving an excess of hydroxide ions (OH-)
  in solution in the remaining water.
• Any solution with more (OH -) than (H) ions is
  alkaline, hence the name of the group
  dissolving these elements in water results in a
  strongly alkaline solution.

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Lithium (Li)

• Lithium is the least dense solid element, and one
  of the most reactive metals
• It was discovered in 1817 by Swedish chemist
  Johan Arfwedson.
• Its atomic number is 3
• The surface of the metal reacts slowly with
  oxygen from the air to form a dull grey layer of
  lithium oxide and hydroxide
• Lithium compounds are used in the glass and
  ceramics industry.
• Characteristic red light produced by a lithium
  compound
• in a flame the light is produced by
  electrons that after
• being excited by heat drop to a lower energy
  level.

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Sodium (Na)

• Sodium is the sixed most abundant element in
  Earths crust, and there are more than 10 kg of
  it, as dissolved sodium ions (Na), in every
  cubic metre of sea water.
• Sodium metal is a soft, silvery metal similar to
  lithium, which will react violently with water,
  producing hydrogen gas.
• Liquid sodium is used as a coolant in some
  nuclear power stations. Pure sodium is used in
  the
• manufacture of sodium lamps (street lighting).
• Atomic number - 11

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Potassium (K)

• Potassium is the seventh most abundant element in
  Earths crust
• The pure metal is produced industrially by
  heating potassium chloride (KCl) from potassium
  bearing minerals with pure sodium vapour.
• Potassium metal reacts violently with water
  being dripped on to it from above.
• The three most important potassium compounds are
• Potassium chloride (KCl)
• Potassium nitrate (KNO3)
• Potassium hydroxide (KOH)
• Potassium was first discovered by English chemist
  
• Humphry Davy
• Atomic number - 19

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Rubidium (Rb)

• It is the sixteenth most abundant element in
  Earth s crust.
• It was discovered in 1861 by German chemists
  Robert Bunsen and Gustav Kirchhoff.
• Only about 3 tonnes of pure rubidium are produced
  each year
• Rubidium melts at 39.3 Celsium it can become
  molten on a hot summer day.
• The radioactive isotope rubidium 87 is used in
• medicine it is absorbed into blood cells.
• Atomic number - 37

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Caesium (Cs)

• Unlike other elements in Group- 1, pure cesium
  has a slide golden tinge.
• It was discovered in 1861 by Robert Bunsen and
  Gustav Kirchhoff.
• The name is from the Latin Caesius, meaning sky
  blue
• Melting point 28.4 C. / Caesium can become
  liquid in a warm room.
• Used in atomic clocks.
• Atomic number - 55

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Francium (Fr)

• This is the last of the alkali metals, discovered
  in 1939 by French physicist Marguerite Perey.
• The element was named after Pereys native
  country.
• It has a melting point of 28 C.
• The largest sample of francium ever prepared,
  consisting of only about 300,000 atoms was made
  by bombarding gold atoms with oxygen atoms.
• Francium occurs naturally, probably not more than
  
• a few grams at any one time in the whole
  world
• It is the product of other radioactive elements

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Thank You!