Periodic General Trends + Patterns

• What is the Aufbau principle?

  states that each orbital must be full (2e) entering at lowest energy level first.
• What is the Hund's rule?

  electrons must occupy equal energy; upwards pointing electron entered first before second electron can be entered.
• What is the Pauli exclusion principle?

  An orbital can only contain 2 electrons.
• What is the symbol for Atomic number?


  Z
• What is the symbol for mass number?

  A
• What are electrostatic forces of attraction?

  Attractions between positively and negatively charged subatomic particles.
• What is an isotope?

  Atoms of same element with same number of protons but a different number of neutrons (mass number).
• What is the 1st ionization energy?

  energy required to remove 1 electron from a neutral atom.
• What is electronegativity?

  Tendency of an atom to attract a bonded pair of electrons.
• What is the general trend in atomic radius across a period?

  Atomic radius decreases across a period because of protons being added to the nucleus. Resulting in greater electrostatic forces of attraction between nucleus and electrons.
• What is the general trend in atomic radius down a group?

  Atomic radius down a group increases because of increasing number of electron shells.
• What is the general trend in electronegativity across a period?

  Electronegativity increases across a period because of increasing number of protons. Resulting in greater electrostatic forces for a bonded pair of electrons.
• What is the general trend in electronegativity down a group?

  Electronegativity decreases down a group because increased distance between VE and nucleus.
• What is the general trend in ionization energy across a period?

  First ionization energy increases across a period because protons are being added to the nucleus making it difficult to take an electron away from the atom.
• What is the general trend in ionization energy down a group?

  First ionization energy decreases down a group because the outermost electron is further from the nucleus meaning less force of attraction.
• What are electrostatic forces of attraction?

  The attraction between oppositely charged cation and anion.
• What is the electron configuration of Chromium?

  $1s^2, 2s^2, 2p^6, 3s^2, 3p^6,4s^1, 3d^5$
• What does AAS stand for?

  Atomic Absorbtion Spectrum
• What is AAS used for?

  Atomic absorption spectroscopy is an analytical technique where absorption spectra of metals is used to determine quantity of metal in unknown sample.
• What is Mass spectrometry?

  Mass spectrometry is analytic technique to determine isotopic composition of elements.
• What is relative isotopic Mass?

  mass of isotopes measured on mass spectrum.
• What is percentage abundance? (%)

  percentage of each isotope contained within a sample of element. (must always added up to 100%)
• what is the Relative Atomic Mass?

  mass of an atom once mass and percentage abundance of all isotopes have been considered.
• What is the rule used to calculate RAM?

  
• How do you calculate percentage abundance?