Ch 14 Periodic Table

• How is the periodic table arranged?

  Elements in periods and groups

  In order of increasing proton number
• What do elements in the same group have in common?

  same number of valence electrons

  digit in ones place of group number = number of valence electrons

  Similar chemical properties -> go through similar types of reactions
• What do elements in the same period have in common?

  Same number of electron shells

  Period number = number of electron shells
• What do metalloids have?

  Properties of both metals and non-metals (except aluminum)

  Found next to diagonal line that divides metals and non-metals
• What happens to properties across a period?


  Increase in non-metallic properties

  Decrease in metallic properties
• What happens to properties across a group?


  Decrease in non-metallic properties

  Increase in metallic properties
• Group 3-12 are transition metals
• Elements with the same number of valence electrons form ions with the same ionic charge
• Noble gases do not form compounds
• Metallic atoms -> more likely to lose electrons

  non-metallic atoms -> more likely to gain electrons to form ions / share electrons to form covalent bonds
• Size of atom increases when going down the group

  lose outermost electrons more easily

  -> further away from attractive forces of nucleus
• group 1 - alkali metals

  group 17 - halogens

  group 18 - noble gases
• What are the physical properties of alkali metals?

  soft, cut easily

  Shiny surface when cut, rapidly tarnishes in air

  Low melting, boiling points

  Low densities
• What happens to physical properties of alkali metals when going down a group?

  melting point of alkali metals decrease

  Densities of alkali metals generally increase
• What happens to chemical properties of alkali metals when going down group?

  Alkali metals become more reactive

  ->size of atom increases

  ->easier to lose valence electrons from bigger atoms
• What are the properties of halogens?

  Have low melting and boiling point

  Coloured

  Exist as diatomic molecules at room temperature and pressure

  reactive non-metals
• What happens to physical properties of halogens when going down group?

  melting and boiling point of halogens increase

  Colour intensities increase
• Alkali metals highly reactive

  Alkali metal + water -> alkali + hydrogen
• What is a displacement reaction?

  Reaction where 1 element takes place of another element in a compound
• In displacement reaction, more reactive halogen displace a less reactive halogen from holide salt

  e.g F2 + 2NaCl -> Cl2 + 2NaF
• How do chemical properties of halogen change when going down group?

  Halogens become less reactive
• What are the properties of noble gases?

  monoatomic non-metals

  colourless gases at room temperature and pressure

  Low melting and boiling point

  Insoluble in water

  Unreactive
• What are the properties of transition elements?

  High melting point

  High densities

  Variable oxidation states

  Coloured compounds -> colours of compounds of transition metals are different at different oxidation states

  Catalysts -> increases rate of chemical reaction by providing an alternative pathway of lower activation energy for the reaction to occur, remains chemically unchanged at the end of a reaction
• Sodium, Potassium and ammonium salts form colourless solutions (CLEAR AND TRANSPARENT ARE NOT ACCEPTED)
• Explain the observation of the product of sodium bromide and chlorine turning from colourless to red-brown

  More reactive chlorine displaces less reactive bromine to form sodium chloride solution
• Describe trends in type of compounds formed across a period

  ON left side of period, elements form only ionic compounds

  Towards right side of period, elements can form ionic or covalent compounds

  Group 18 elements are unreactive and will not form compounds
• Common oxidation states

  Chromium +3 / +6

  Manganese +2 / +4 / +7

  Iron +2 / +3

  Copper +1 / +2
• Coloured oxidation states of transiton metal compounds - chromium

  Chromium (III) chloride - green

  Potassium dichromate (VI) - orange
• Coloured oxidation states of transiton metal compounds - iron 


  iron (II) sulfate - pale green

  iron (III) chloride - yellow
• Coloured oxidation states of transiton metal compounds - manganese 


  manganese (IV) oxides - brown-black

  potassium manganate (VII) - purple
• Coloured oxidation states of transiton metal compounds - copper


  Copper (II) oxides (solid) - red

  Copper (III) oxides solid - black

  Copper (II) sulfate solution - blue