Periodicity

• Identify the element in Period 4 with the largest atomic radius.Explain your answer. (3)


  • Potassium
  • smaller nuclear charge 
  • Similar shielding 
• Explain why the melting point of sulfur (S8) is greater than that of phosphorus (P4). (2)


  •  S8 molecules are bigger than P4 moleculeVDW forces between S molecules stronger 
• Explain why the atomic radii of the elements decrease across Period 3 from sodium to chlorine. (2)


  • Nuclear charge increases 
  • Attraction between nucleus and electrons increases 
• Identify the element in Period 4 with the highest electronegativity value


  Br
• Identify the element in Period 3, from sodium to chlorine, that has the highest electronegativity.


  Cl
• Explain why the atomic radius decreases across Period 3, from sodium to chlorine. (2)


  • Nuclear charge increases 
  • similar shielding 
• Identify the element in Period 3, from sodium to argon, that has the highest second ionisation energy.


  Na
• There is a general trend for an increase in ionisation energy across Period 3. Give one example of an element that deviates from this trend.

  Explain why this deviation occurs. (3)

  • Al
  • electron in 3p orbital 
  • Is higher in energy

   

  • S
  • Electron in 3p orbital pairs 
  • Pairing causes repulsion
• Bonding 


  bonding

  
• What happens to Si in MP (3)


  • Large increase 
  • giant molecular structure 
  • lots of energy required to break bonds 
• Explain the MP between Na and Al (2)


  • Increases 
  • Due to metallic bonding there is a larger charge and smaller ions 
• What is the most electronegative element 


  Cl
• What happens to electro negativity across a period


  increases
• Why does S deviate from the trend 


  • Lower IE
  • extra electron in 3p oribital 
  • pairing causes repulsion 
• Why does Al deviate from the trend in IE 


  • IE lower 
  • extra electron in 3p orbital 
  • electron easier to remove 
• IE across P3


  increases

  
• What factors affect IE (3)


  • nuclear charge (increased charge means increased IE
  • distance from nucleus (increased distance decreases IE
  • increased shielding (decreases IE)
• What happens to ionisation energy across a period 


  Increases due to similar shielding 
• What is atomic radius 


  Distance from nucleus to electrons in outer energy level 
• What happens to the nuclear charge across a period 


  Increases due to greater attracted for electrons 
• What does periodicity mean 


  Repeating trends of physical or chemical properties 
• What does ionisation energy mean 


  Energy required to remove 1 mol of electrons from 1 mol gaseous atoms 
• What is the trend in atomic radius across a period 


  decreases
• Different orbitals 


  spdf