Constitutional Isomerism & Writing Structural Formulas

Question 1

What does the molecular formula of a compound indicate?

Answer 1

number and type of different atoms present

e.g. ethane (C2H6 , 2 carbons, 6 hydrogens)

Question 2

What does the structural formula indicate?

Answer 2

number and type of different atoms present (same as molecular formula) BUT ALSO the pattern of connectivity between atoms in the molecule.

Question 3

An example of why both molecular and structural formula are important:

Answer 3

Think about the compound water. The Molecular formula of water is H2O, so it could be said that water is a compound made up of two hydrogen atoms and one oxygen atom.
However, without further explanation, it may (incorrectly) be assumed that the hydrogens were connected to each other followed by the oxygen (H-H-O), instead of the correct structure (H-O-H), with each of the two hydrogens connected to the central oxygen.

Question 4

What are isomers?

aka constitutional/structural isomers.

Answer 4

compounds with the same molecular formula that have different connectivity (arrangement) between the atoms in their structural formulae.

Question 5

T or F: Small changes in connectivity don’t have much of an impact on the properties and reactivity of a molecule.

Answer 5

False