What is this? 037

A diagram of organic compounds with rings

nitrogen, hydrogen, oxygen, sulfur, silicon, and phosphorus

carbon is implied by the junction between two line segments

hydrogen is implied anywhere there is a carbon with less than 4 bonds.

double bonds

5 carbons

5; 1 shown and 4 implied

In diagrams of organic molecules, hydrogens are shown unless they are attached to carbons

These label the atoms in the ring, starting with the non-carbon atom. These numbers are used to name compounds derived from these molecules with an atom substituting for one of the hydrogens.

For instance, this is 2-chloropyridine:

This is 3-chloropyridine:

Symmetry

Substituting an element at what would be the carbon in the 6th position of phosphorine would be the same as substituting in the 2nd position. 6-chloropyridine would be the same as 2-chloropyridine.

However, once one substitution has been made, it breaks the symmetry and adding a second substitution might require numbering the other atoms up to 6.

This is 2,6-dichloropyridine:

• Basic chemistry
  • Recognizing symbols of elements
• Interpreting diagrams of organic compounds
  • Implied carbons and hydrogens
  • Single and double bonds
  • Numbering system