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Drafting pantograph in use Pantograph used for scaling a picture. The red shape is traced and enlarged. Pantograph 3d rendering. A pantograph (from Greek παντ- 'all, every' and γραφ- 'to write', from their original use for copying writing) is a mechanical linkage connected in a manner based on parallelograms so that the movement of one pen, in tracing an image, produces identical ...
Ring opening as a means of ring expansion can also be applied to larger systems to give access to even larger ring syscyclization. The Grob fragmentation can be applied as an example of such an expansion. Like the pinacol type migration the Grob fragmentation relies on an electron donating group to promote the bond migration and encourage the ...
A normal experiment may involve 1–10 mL solution with an analyte concentration between 1 and 10 mmol/L. More advanced voltammetric techniques can work with microliter volumes and down to nanomolar concentrations. Chemically modified electrodes are employed for the analysis of organic and inorganic samples.
The polar substituent constants are similar in principle to σ values from the Hammett equation, as an increasing value corresponds to a greater electron-withdrawing ability. Bent's rule suggests that as the electronegativity of the groups increase, more p character is diverted towards those groups, which leaves more s character in the bond ...
Ab initio means "from first principles" or "from the beginning", implying that the only inputs into an ab initio calculation are physical constants. [5] Ab initio quantum chemistry methods attempt to solve the electronic Schrödinger equation given the positions of the nuclei and the number of electrons in order to yield useful information such ...
Example: P 4. Electron count: 4 × P = 4 × 5 = 20 It is a 5n structure with n = 4, so it is tetrahedral. Example: P 4 S 3. Electron count 4 × P + 3 × S = 4 × 5 + 3 × 6 = 38 It is a 5n + 3 structure with n = 7. Three vertices are inserted into edges. Example: P 4 O 6. Electron count 4 × P + 6 × O = 4 × 5 + 6 × 6 = 56 It is a 5n + 6 ...
Physical chemistry, in contrast to chemical physics, is predominantly (but not always) a supra-molecular science, as the majority of the principles on which it was founded relate to the bulk rather than the molecular or atomic structure alone (for example, chemical equilibrium and colloids).
A gas pycnometer is a laboratory device used for measuring the density—or, more accurately, the volume—of solids, be they regularly shaped, porous or non-porous, monolithic, powdered, granular or in some way comminuted, employing some method of gas displacement and the volume:pressure relationship known as Boyle's law.