[chem] optical & geometric isomers

diff --git a/chem/organic-2.md b/chem/organic-2.md
index 05cfd7482b539ba567f82d30cd7b16a1e9eb24d0..8543168458cca4fc35b27a1f213bfeab056d9b22 100644 (file)
--- a/chem/organic-2.md
+++ b/chem/organic-2.md
@@ -1,12 +1,15 @@
 ---
+geometry: a4paper, margin=2cm 
 header-includes:
 - \usepackage{mhchem}
+- \usepackage{chemfig}
 - \usepackage{tabularx}
 ---
 
 # Organic Chemistry
 
 Large number of compounds due to:
+
 - 4 valence pairs
 - single / double / triple bonds
 - cyclic (ring) structures
@@ -32,8 +35,6 @@ Alkynes: \ce{C_{$n$} H_{$2n-2$}}
 - Indicate number of branches with di-, tri- etc.
 - Longest unbranched carbon chain includes function group
 
-
-
 ## Functional groups
 
 \begin{tabularx}{\textwidth}{rX}
@@ -45,3 +46,20 @@ Alkynes: \ce{C_{$n$} H_{$2n-2$}}
   Amides & \ce{-CONH2} \\
 \end{tabularx}
 
+
+## Isomers
+
+* **Structural isomers** - same molecular formula, different arrangement  
+* **Stereoisomers** - same structural configuration, different orientation  
+  * **Opotical isomers** - chiral centre, 4 groups bonded to C, non-superimposable mirror image
+  * **Geometric isomers** - \ce{C=C} double bond, 2 groups bonded to carbon atoms
+    + **Cis** - same horizontal plane
+    + **Trans** - diagonal
+
+\setlength\tabcolsep{1cm}
+\begin{tabularx}{\textwidth}{cc}
+  cis & trans \\
+  \chemfig{[:60]{\text{\color{blue}R$^\prime$}}-C(-[:120]{\text{\color{red}R}})=[0]C(-[:-60]{\text{\color{blue}R$^\prime$}})-[:60]{\text{\color{red}R}}} &
+  \chemfig{[:60]{\text{\color{blue}R$^\prime$}}-C(-[:120]{\text{\color{red}R}})=[0]C(-[:-60]{\text{\color{red}R}})-[:60]{\text{\color{blue}R$^\prime$}}}
+\end{tabularx}
+