EL 5

• Periods in the periodic table


  • Elements in the same period have the same number of electron shells
• Groups in the periodic table

  • Elements in the same group have the same number of electrons in the outer shell
• S block elements

  • Have their highest electron in the S orbital
• P block elements

  • Have their final electron in the P orbital
• The elements in the modern periodic table are ordered by proton number, not by mass number
• Melting points increase across Period 3 in the periodic table due to increasing positive charge, more delocalized electrons, and smaller ionic radius
• F block elements


  • Also known as F block elements
• Silicon has the highest melting point in Period 3 due to its giant covalent or macro-molecular structure
• D block elements

  • Located in the middle and have their electrons in the D orbital
• Sulfur has a slightly higher melting point than phosphorus due to its larger molecule size
• Phosphorus has a lower melting point than silicon due to its simple molecular structure and weaker intermolecular forces
• Chlorine

  • Formula: Cl2
  • Smaller melting point than phosphorus and sulfur due to smaller molecule and smaller intermolecular forces
• Argon

  • Doesn't form bonds like Cl2, S8, or P4
  • Lower melting point than the rest due to being an individual atom with smaller intermolecular forces
• Sulfur

  • Formula: S8
  • Higher melting point than phosphorus due to larger molecule and larger intermolecular forces
• Bonds

  • sodium
  • magnesium
  • aluminium
  • silicon
  • sulfur
  • phosphorus
  • chlorine
  • argon
• First ionization energy of sodium is endothermic, represented by the equation: Sodium -> Na+ + e-
• Ionization is the minimum amount of energy required to remove one mole of electrons from one mole of atoms in the gaseous state
• Ionization energy decreases as we go down a group, atomic radius increases, outer electrons are further from the nucleus, and the attractive force is weaker
• Ionization energy increases as we go across a period, more protons lead to increased nuclear charge and stronger attraction between protons and outer electrons
• Shielding increases as we go down a group, more shells between the nucleus and outer electrons weaken the attractive force
• There are exceptions or blips in the data when looking at ionization energy across a period
• Magnesium reacts with oxygen to form magnesium oxide
• Trend of ionization energy is similar for period two elements
• Reactivities of group two elements increase as we go down the group
• Ionization energy increases as we go across a period
• Alkaline solutions are formed when group two elements are added to water
• Group two oxides react with water to form hydroxides, producing aqueous hydroxide ions which make the solution alkaline
• Group two elements react with water and oxygen to form bases
• Beryllium doesn't react with water
• Reaction with water to form metal hydroxide

  • Strontium with water forms strontium hydroxide and hydrogen gas
• Magnesium reacts more vigorously with steam than with cold water
• Group two hydroxides become more soluble as we go down the group, leading to stronger alkaline solutions
• Group two metals form white solids when reacting with oxygen
• Group two hydroxides and carbonates have opposite solubility trends as we go down the group
• Ionization energy trend across a period

  General increase due to more protons and increased nuclear charge leading to a bigger attraction between protons and the nucleus and the outer electrons. Shielding remains similar, but the distance from the nucleus marginally decreases across the period, making it more difficult to remove the electron
• Group two bases can neutralize acids to form salts and water
• Barium carbonate is very sparingly soluble, while magnesium carbonate is very soluble
• Group two hydroxides and carbonates have opposite solubility as we go down the group
• If the anion has a double charge, the compound becomes less soluble as we go down the group
• Understanding solubility is very important, especially for group two compounds