Mechanical Drawing Symbols

The vector stencils library "Chemical elements" contains 118 icon symbols of chemical elements for drawing atoms, structural formulas and ball-and-stick models of inorganic and organic molecules and ions, and schemes of chemical reaction mechanisms.
"In chemistry, the ball-and-stick model is a molecular model of a chemical substance which is to display both the three-dimensional position of the atoms and the bonds between them. The atoms are typically represented by spheres, connected by rods which represent the bonds. Double and triple bonds are usually represented by two or three curved rods, respectively. In a good model, the angles between the rods should be the same as the angles between the bonds, and the distances between the centers of the spheres should be proportional to the distances between the corresponding atomic nuclei. The chemical element of each atom is often indicated by the sphere's color." [Ball-and-stick model. Wikipedia]
The chemical symbols example "Design elements - Chemical elements" was created using the ConceptDraw PRO software extended with the Chemistry solution from the Science and Education area of ConceptDraw Solution Park.

"Citric acid cycle (tricarboxylic acid cycle, TCA cycle, Krebs cycle) is a series of chemical reactions used by all aerobic organisms to generate energy through the oxidation of acetate derived from carbohydrates, fats and proteins into carbon dioxide and chemical energy in the form of adenosine triphosphate (ATP)." [Citric acid cycle. Wikipedia]
This biochemical diagram example shows metabolic pathways map of citric acid cycle reactions.
This sample was redesigned from the Wikimedia Commons file: TCA cycle.svg. [commons.wikimedia.org/ wiki/ File:TCA_ cycle.svg]
This image is licensed under the Creative Commons Attribution 3.0 Unported license. [creativecommons.org/ licenses/ by/ 3.0/ deed.en]
The metabolic pathway map example "Citric acid cycle (TCA cycle)" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Biology solution from the Science and Education area of ConceptDraw Solution Park.