The Periodic Table

• Dmitri Mendeleev produced his periodic table

  1869
• Mendeleev knew that there had to be undiscovered elements because if he arranged the elements in the order he worked out they would have the wrong properties for the groups they went into
• Mendeleev left gaps in the periodic table to account for undiscovered elements
• Group 0

  Noble gases
• Group 1

  Alkali Metals
• As you go down group 1

  The metals get progressively more reactive
• Scientists initially found it hard to arrange the elements because they hadn't all been discovered yet
• When protons and electrons were discovered, chemists found it easier to put the elements in the correct order and groups
• Placing elements in atomic number order

  Also atomic radius order decreasing
• Elements of each group

  Have the same number of electrons in their outer shell
• The number of shells an atom has

  Increases as you go down the periods
• Properties of Group 1 (Alkali Metals)

  All have one electron in their outer shell
• An observation of Lithium, Sodium and Potassium reacting with water is bubbling
• An observations of sodium reacting with water is the metal forms a ball shape
• An observations of potassium reacting with water is the metal forms a ball shape
• All group one metals need to lose their one outer electron
• It is easier for metals further down the group to lose their outer electron

  Because it is further from the nucleus, so there is a weaker electrostatic attraction between the outer electron and the nucleus
• Similarities between the alkali metals and the transition metals

  Conduct heat and electricity
• Differences between the alkali metals and the transition metals

  Low melting points (Alkali metals), high melting points (Transition metals)
• The halogens get less reactive the further down the group you go

  Because when the halogens react they gain one electron in order to get a full outer shell, and the further down the group the outer shell is further away from the nucleus, so there is a weaker electrostatic attraction between the outer electrons and the nucleus, making the electron harder to gain, and the halogen less reactive
• Halides

  Compounds containing halogens
• A more reactive element can displace a less reactive element in a compound
• The halogens get less reactive the further down the group, which can be seen by looking at which halogens can displace each other from compounds
• The periodic table is an arrangement of the elements according to their atomic number.
• Periods are rows on the periodic table.
• Groups (or columns) are vertical lines on the periodic table.
• Properties of Group 1 (Alkali Metals)

  all alkali metals always form a 1+ ion
• Properties of Group 1 (Alkali Metals)

  alkali metals react with oxygen to form metal oxides that are white powders (metal + oxygen → metal oxide)
• Properties of Group 1 (Alkali Metals)

  Alkali metals all burn in chlorine to form metal chlorides which are white powders (metal + chlorine → metal chloride)
• Properties of Group 1 (Alkali Metals)

  alkali metals all react with water, releasing hydrogen, forming a solution containing a metal hydroxide (metal + water → metal hydroxide + hydrogen) (the solution formed is alkali)
• Properties of Group 1 (Alkali Metals)

  Compounds made from alkali metals are ionic, white solids and dissolve in water to form colourless solutions
• An observation of lithium, sodium and potassium reacting with water is the metal floats
• An observations of Lithium, Sodium and Potassium reacting with water is

  the metal moves
• An observations of Lithium, Sodium and Potassium reacting with water is the metal becomes smaller
• Observations of Lithium, Sodium and Potassium reacting with water
Universal indicator added to the water turns blue or purple
• Properties of Group 1 (Alkali Metals)

  All elements are metals
• Properties of Group 1 (Alkali Metals)

  All the metals react easily with non-metals and form ions
• Properties of Group 1 (Alkali Metals)

  Elements have low densities for metals (Lithium, sodium and potassium all float on water)
• Properties of Group 1 (Alkali Metals)

  Low melting points (meting points decrease going down the group)
• Properties of Group 1 (Alkali Metals)

  All metals are solids at room temperature