M = Σ nᵢ MᵢM: molar mass in g/mol; nᵢ: number datoms of lelement i.
Use when: Add all contributions from the raw formula.
Building and representing molecules
Link formula, connectivity, valence and geometry of organic molecules.
What is happening?
A crude formula counts atoms; a developed formula specifies their connections. Two molecules with the same molecular formula can have different connectivities or spatial arrangements.
In usual neutral organic molecules, carbon generally forms four bonds in the sense of the sum of the bond orders. Planar representations are not always sufficient to describe stereochemistry.
The formulas, with their conditions.
I = (2C + 2 + N − H − X) / 2I: dunsaturation index; C, N, H, X: numbers d atoms; X: halogens.
Use when: Usual formula for neutral closed molecules with conventional valences; O and S do not enter into this count.
Where is this principle used?
Pharmaceutical industry
Identify structures and relationships between chemical families.
Solvent and Polymer Plant
Choose a chemical function and understand its reactivity.
What to observe in the experiment
Construct two structures with the formula C₂H₆O. Compare their functions without changing the total number of atoms.
References and readings
This sheet explains the principles and their assumptions. Educational simulation can simplify the process; an industrial model requires suitable data and validation.
Have you understood the essentials?
Only one correct answer per question. Answer all three questions, then view the answer key.
Intu Lab · Understanding sheet · Kimba Christian