Atomic Theory

Question 1

A and Z Numbers

Answer 1

• A number refers to the atomic mass
  
  • Or number of protons and neutrons
• Z number refers to the atomic number
  
  • Or number of protons

Question 2

Effective Nuclear Charge

Answer 2

• The effective nuclear charge is the net charge exerted upon the valence electrons
  
  • The nuclear charge is added to the core electron charge (negative) to get the effective nuclear charge, Z_eff

Question 3

Paramagnetism and Diamagnetism

Answer 3

• Paramagnetism is defined as an atom or molecule that contains at least one unpaired electrons (radicals are paramagnetic)
• Diamagnetism is defined as an atom or molecule that contains no unpaired electrons

Question 4

Quantum Numbers

Answer 4

• n is principal__​
  
  • Can be any integer greater than 0
• l is angular momentum
  
  • _​_Must be less than the value for n
• m_<em>l</em>* *is magnetic
  
  • _​_Can be any value from negative l to positive l
• m_s is spin
  
  • Can either be 1/2 or -1/2
• Each electron has a unique quantum number

Question 5

General Elemental Periodic Trends

Answer 5

• As you move from left to right across a period, Z_eff increases
• As you descend a family in the periodic table, the valence shell increases, so the distance between the atom’s valence electrons and its nucleus increases

Question 6

From Bottom Left to Top Right

Atomic Size

Ionization Energy

Electron Affinity

Electronegativity

Answer 6

• Decreasing valence shell and increasing Z_eff
• Atomic size decreases
  
  • Radius of atom defined as the distance from the center of the nucleus to the exterior of the valence electron cloud
• Ionization energy increases
  
  • Energy required to remove the outermost electron from the atom
• Electron affinity increases
  
  • Energetics associated with an atom gaining an electron
  • More exothermic (negative) is larger
• Electronegativity increases
  
  • The tendency to hold shared electrons with another atom within a bond

Question 7

Nuclear Particles

Answer 7

• Alpha particle is the same as a helium atom
  
  • a = 4, z = 2
• Beta particle is the same as an electron
  
  • a = 0, z = -1 (no mass contribution)
• Positron particle is the same as a postively charged electron
  
  • a = 0, z = 1

Question 8

Nuclear Decay and Nuclear Capture

Answer 8

• Heavy elements undergo nuclear decay to become more stable
  
  • Fission
• Lighter elements undergo nuclear capture when struck by a high-energy particle to increase mass to become more stable
  
  • Fusion