Overview
This lecture covers the unique physical property trends of transition metals, including atomic size, electronegativity, ionization energy, and density, comparing them to main group elements.
Periodic Trends in Transition Metals (Across a Period)
- Atomic size decreases at first but then remains relatively constant across a period in transition metals.
- In main group elements, atomic size consistently decreases across a period.
- Electronegativity of transition metals remains relatively constant and intermediate across a period.
- Main group elements show a general increase in electronegativity across a period.
- Ionization energy in transition metals increases slightly but remains relatively constant across a period.
- Main group elements show a steady increase in ionization energy across a period.
- Shielding by inner (d orbital) electrons stabilizes these trends in transition metals.
Group Trends in Transition Metals (Down a Group)
- Atomic size increases from period 4 to 5, then remains nearly constant from period 5 to 6.
- Electronegativity increases from period 4 to 5, but shows little or no further increase from period 5 to 6.
- Gold is an exception with unusually high electronegativity due to its large atomic mass.
- Ionization energy generally increases down a group for transition metals.
- As ionization energy increases down a group, reactivity tends to decrease.
- Density increases down a group, with period 6 transition metals (like gold, tungsten, platinum) being among the densest elements.
Density, Atomic Size, and Volume
- Density = Mass/Volume; as atomic size and volume increase, density changes depending on mass.
- Period 6 transition metals (including lanthanides and others like hafnium, gold, tungsten, platinum) are especially dense.
Key Terms & Definitions
- Atomic Size (Atomic Radius) — The average distance from the nucleus to the outermost electrons.
- Electronegativity — An atom's tendency to attract electrons in a bond.
- Ionization Energy — The energy required to remove an electron from a gaseous atom or ion.
- Density — Mass per unit volume; indicates how closely packed atoms are in a solid.
Action Items / Next Steps
- Review electron configuration and its effect on atomic properties.
- Read Chapter 10.6 for more details on density and transition metal properties.
- Prepare for upcoming material on chemical properties and reactivity of transition metals.