electron structure

• what does the principle quantum number indicate

  the shells occupied by the electrons
• how many electrons can the first shell hold

  2
• how many electrons can the second shell hold

  8
• how many electrons can the third shell hold

  18
• how many electrons can the fourth shell hold

  32
• What is an orbital?

  a region around the nucleus that can hold up to two electrons with opposite spins
• shape of s orbital


  spherical
• shape of p orbital

  dumbbell shape
• how many electrons can be held in a s subshell?

  2
• how many orbitals does a p sub shell have?

  3
• how many electrons can be held in a p sub shell?

  6
• how many orbitals are present in a d subshell?

  5
• how many electrons can be held in a d sub shell?

  10
• how many orbits are found in a sub shell?

  7
• how many electrons can fill an f shell?

  14
• from which shell onwards is s orbital present?

  n=1
• from which shell onwards is p orbital present?

  n=2
• from which shel onwards is d orbital present?

  n=3
• from which shell onwards is f orbital present?

  n=4
• what are the rules by which electrons are arranged in the shel?

  • electrons are added one at a time
  • lowest available energy level is filled first
  • each energy level must be filled before the next one can fill
  • each orbital is filled singly before pairing
  • 4s is filled before 3d
• why does 4s orbital fill before 3d orbital?

  4s orbital has a lower energy than 3d orbital
• which electrons are lost when an atom becomes a positive ion?

  electrons in the highest energy levels