The periodic table lists elements from left to right, top to bottom, in order of their atomic number. While studying for the Physical Sciences section of the MCAT, you should keep the periodic table handy to have a visual reference of the material that you are reviewing.
Electronegativity. Electronegativity refers to the tendency of an atom to attract electrons that are shared with other atoms. For example, oxygen is the more electronegative atom in water. The oxygen’s nucleus is so much larger than that of hydrogen that the shared electrons spend more time around the oxygen than around the hydrogen. On the periodic table, electronegativity increases across the periodic table to the right and up. Noble gases have an undefined electronegativity.
Electron Affinity. Electron affinity refers to the ability to an atom to accept an electron in a bond. On the periodic table, electron affinity increases across the periodic table to the right and up.
Ionization Energy. Ionization energy refers to the amount of energy required to detach an electron from the nucleus. This coincides with the logic above concerning electronegativity. On the periodic table, ionization energy increases across the periodic table to the right and up.
Useful MCAT Tips
Know the following groups and some of their fundamental characteristics:
- Alkali Metals
- Alkaline Earth Metals
- Noble Gases
Remember that the atomic number tells you everything you need to know about the atom itself, including the number of protons, neutrons, and electrons.
Use the visual depiction of the elements to remember useful elemental and atomic properties, such as valence electrons and oxidation numbers.
It is very unlikely that you will see any chemistry questions concerning Lanthanides or Actinides. However, it is very likely you will see questions involving elements from the four groups mentioned above as well as non-metals.
Next: Chemical Bonding.