Periodic table

• main-group elements (or representative elements)
• transition metal (or transition element)
  • inner transition metals

Periodic trends

(source: commons.wikimedia.org)

• atomic radius
• ionization energy
  • The ionization energy of an atom or ion is the minimum energy required to remove an electron from the ground state of the isolated gaseous atom or ion
  • Highest for noble gases and halogens
  • Lowest for alkali metals (bottom left)
• electron affinity
  • Lowest for noble gases and alkali metals
  • Highest for halogens
• electronegativity
  • Follows a similar trend to electron affinity
  • Increases from bottom left to top right of the periodic table
• effective charge (Z-effective)

Effective Nuclear Charge (Z-effective)

$Z_{\mathrm{eff}}=Z-S$

• $Z_{\text{eff}}$ is effective nuclear charge
• $Z$ is the atomic number (number of protons)
• $S$ is the shielding constant
  • It represents the portion of the nuclear charge that is screened from a valence electron by the other electrons in the atom.
  • Because core electrons are most effective at screening a valence electron from the nucleus, the value of is usually close to the number of core electrons