Question

MCAT Mini-Tutorial: Understanding the Periodic Table

Answer 1

\({\bf{Basic~Layout:}}\)
- period: rows
- group: columns, elements in a group tend to share chemical properties
- group 1: alkali earth (red on this diagram, excludes hydrogen), very reactive
- group 2: alkaline earth metals (yellow), reactive but less so than group 1
- transition metals: d-block, light blue, partially filled d orbitals allow them to react w/, combine w/ other elements
- rare earth elements: f-block, pink, first row is actinides and second row is lanthanides
- group 7: halogens, very reactive
- group 8: noble gases, non-reactive
- transition metals: the blue-ish "staircase" between the transition metals and the nonmetals

\({\bf{Classifying~Elements}}\)
- metals: conductive, ductile, malleable, solid at room temp.
- nonmetals: nonconductive, brittle, gaseous at room temp
- metalloids: intermediary properties between metals and nonmetals

\({\bf{Periodic~Trends:}}\)
- atomic radius: 1/2 the distance between adjacent nuclei
> decrease across period (more protons, same energy level, stronger effective nuclear charge)
> increase down group (increase of shielding from lower energy levels)

- first ionization energy: energy required to remove electron in gaseous state
> increases across period (more protons, same energy level, stronger effective nuclear charge)
> decrease down group: (increase of shielding from lower energy levels, easier to remove electrons)
> subsequent ionization energy: increases as more electrons are removed (removing electrons increases the effective nuclear charge per remaining electron)

- electron affinity: energy change of gaining an electron in gaseous state
> same trends as ionization energy

- electronegativity: affinity for electrons
> same trends as ionization energy
> metals have low EN, nonmetals have high EN, noble gases are not given EN since they are not reactive

misc:
- francium has lowest EN and largest radius
- cesium is the most reactive

Answer 2

Anyway, that's the end of my tutorial, I hope it was a helpful resource. Source material is the 2nd Edition Barron's Prep book for the new MCAT