periodic table

• groups: vertical columns

  periods: horizontal rows
• ionization energy is a measure of the ability of an atom to lose electrons
• electronegativity is a measure of the ease of an atom to gain electrons to form negative ions
• atomic radius is a measure of the size of an atom
• group two (alkaline earth metals)

  all the elements have 2 electrons in their outer shell and must lose 2 electrons to achieve a stable electrical conductivity
• physical properties of group two

  • increase in atomic radius going down the group
  • high melting and boiling point due to the strong metallic bonds and they thus decrease as you go down the group as the strength of the metallic bonds weaken
  • ionization energy decreases as you go down the group
  • can conduct electricity
  • solid at room temp and pressure
  • high densities
• bigger atoms lead to bigger cations, the cations are closer to the nucleus and cloud of electrons leading to weaker bonds
• chemical properties of group 2

  • reducing agents
  • reducing power increases as you descend down the group
  • reactivity increases as you go down the group because it is easier to lose electrons
  • metals react with dilute acids to form a salt and hydrogen gas
  • react with water to produce metallic hydroxide and hydrogen gas
  • solubility of the oxides and hydroxides increases as the group descends
  • oxides and hydroxides are basic
• group seven(halogens)

  fluorine bromine chlorine and iodine
• group 2

  beryllium, magnesium calcium strontium barium radium
• physical properties of group 7

  • melting points and boiling points increase down the group due to vander-waals forces
  • atomic radius increases as there is more inner shells
  • form diatomic molecules
  • gas to liquid as intermolecular forces get stronger
  • colour intensity increases due to stronger intermolecular forces
  • electronegativity decreases as it is harder to gain electrons
• chemical properties of group seven

  • 7 electrons in outer shell
  • react by gaining( a gain of electrons is a reduction)
  • oxidising agents as they gain electrons
  • main oxidation state is -1
  • reactivity decreases as you go down the group
  • form diatomic molecules with themselves
  • react with metals to form ionic compounds
  • react with non metals to form covalent bonds
  • a more reactive non metal can displace a less reactive metal from a solution of its salt
• periodic trends

  • the number of shells across the period stays the same
  • # of electrons increases
  • screening effect stays the same
  • the atomic radius increases
  • ionisation energy increases
  • electronegativity increases
  • reactivity decreases
• reactivity increases in the non metals across the period because as you go down the group the radius is smaller and there is a strong attractive force between the nucleus and valence shell making it easier to gain electrons
• why does the melting and boiling points decrease down the group

  strength of metallic bonds weaken
• Alkaline earth metals


  Group two metals in the periodic table
• Alkaline earth metals


  • Beryllium
  • Magnesium
  • Calcium
  • Strontium
  • Barium
  • Radium
• Alkaline earth metals


  • Have two electrons in their valence shell
  • Can lose these valence electrons to form an ion with a +2 charge
  • Similar properties and reactivity trends to the alkali metals
  • Stored in oil (except magnesium)
• Moving down the group

  • Density and reactivity increases
  • Melting and boiling points decrease
  • Metals become softer
• The reaction of calcium with water is more vigorous than the reaction of magnesium with water
• Group seven elements


  • Fluorine
  • Chlorine
  • Bromine
  • Iodine
  • Astatine
  • Tennessine
• Halogens


  • Fluorine is a poisonous yellow gas and very reactive
  • Chlorine is less reactive and a poisonous green gas
  • Bromine is a ready brown volatile liquid and poisonous
  • Iodine is a dark gray solid that can form poisonous purple vapors, but is also an antiseptic
• Diatomic molecules


  Two atom molecules formed by halogens sharing electrons and forming covalent bonds
• Simple molecular structures


  Compounds formed by halogens forming covalent bonds with other non-metals such as hydrogen or carbon
• As you go down the halogen group

  Melting and boiling points increase, reactivity decreases
• Halides


  Ions formed when a halogen gains an electron, with names ending in -ide
• Halides


  • Fluoride
  • Chloride
  • Bromide
  • Iodide
• Displacement reactions


  More reactive halogens displace less reactive ones
• Noble gases


  • Colorless gases
  • Inert (don't react)
  • Exist as single atoms
  • Non-flammable
• As you go down the noble gas group


  Boiling points increase