The Critical Properties Section contains four fields for the following properties:

The Abbreviations Dialog shows the definitions of all the abbreviations used in Cranium and Synapse. To activate the dialog, select the Help menu's Abbreviations command. See here for documentation.

Each field contains a label, a datum control, an estimates control, and a units control. The units controls for the critical compressibility field is not active because this property is dimensionless.

1	Datum Control: displays the field's physical property's data value. A green triangle in the datum control's upper right corner indicates that additional data are available. (See below.)
2	Estimate Control: displays the field's physical property's estimated value.
3	Units Control: displays the current units for the field's physical property. Note that this field is displayed but inactive if the physical property is dimensionless.

All the fields in this section contain numerical values. Thus, they all appear similar and are edited in the same manner.

The Data column of each field displays a physical property data value. The data value is displayed in the units shown in the Units column. A green triangle in the data control's upper right corner indicates that additional data are available. (See documentation on the Datum-Reference All Data Dialog and the Datum-Units-Reference All Data Dialog for details on managing data having different status.)

If the field's property is dimensionless, the Datum-Reference Edit Dialog is activated. (See here for documentation.) If the field's property has units, the Datum-Units-Reference Edit Dialog is activated. (See here for documentation.)

Clicking the right mouse button within the field's datum control activates the field's datum commands menu.

The menu's commands enable you to copy, cut and paste values to and from the data control. See Common Menu Commands for documentation on the commands commonly found on command menus. See below for documentation on this field's specific menu commands.

• Edit All Data: uses the All Data dialog to enable editing data having status values of passive, rejected or unknown. See Datum-Reference All Data Dialog and Datum-Units-Reference All Data Dialog for documentation.)
• Edit Data: enables you to view and modify the current physical property's datum. The property value, accuracy, units of measure, reference and comments can be viewed and edited. See Datum-Reference Edit Dialog and Datum-Units-Reference Edit Dialog for detailed documentation.

  Each property field runs a set of verification tests to check the validity of an entered value. Specifically:

  • Critical Temperature (Tc): value must be greater than 0.0 K
  • Critical Pressure (Pc): value must be greater than 0.0 Pa
  • Critical Volume (Vc): value must be greater than 0.0 kg/m3
  • Critical Compressibility (Zc): value must be greater than 0.0

  Cranium or Synapse will signal an error if the entered value fails a physical property verification test.

The Estimates column of each field displays the physical property's estimated value. The value is displayed in the units shown in the Units column.

Clicking the left mouse button on an estimate control activates the Estimation Details dialog.

The Estimation Details dialog shows the estimated value, the technique used to generate the estimate, and any comments generated during the estimation. The dialog also has two buttons to provide more information about the technique used to generate the estimate:

• Tech Notes: displays the general notes associated with the estimation technique.
• Tech Ref: display the document associated with the technique's reference.

The estimated value control of each field displays the physical property's estimated value. Unless the property is dimensionless, the value is displayed in the units shown in the field's Units control.

Clicking the right mouse button on the estimate control displays the commands menu.

The menu's commands enable you to copy values, clear values and manage the property's estimation techniques. See Common Menu Commands for documentation on the commands commonly found on command menus. See below for documentation on this field's specific menu commands.

• Compute Estimate: activates the Property Estimation dialog which enables you to estimate the current physical property. The functionality of this command is similar to that of the Commands menu's Compute Estimates command. The key difference is that the estimates control's menu command limits the estimation to only the current physical property. See Estimating Chemical Properties for additional documentation.
• Select Technique: enables you to specify the estimation mode and the estimation technique used to estimate the current physical property. Selecting this command activates the Estimation Technique Information dialog.

  The dialog lists two estimation modes: Automatic and Manual. By default all estimations are initially set to Automatic Mode. Once you choose Manual Mode, the list of estimation techniques is enabled allowing you to choose any estimation technique known to the application. See documentation on Manual Techniques Dialog for details about manually selecting estimation techniques.
• Detail Estimate: activates the Details Dialog displaying information about the estimation technique used. See documentation on the Estimate-Technique Detail Dialog and the Estimate-Units-Technique Dialog for details.

Note that values cannot be pasted into a field's estimated value control.

Selecting new units from the list and press the OK button changes the current units in which the property is displayed. (Note that all data are stored in their original units - changing the displayed units does not change any stored data.) The dialog's Std Units button displays the default units used by Cranium and Synapse for the current physical property. All estimated values are generated by Cranium and Synapse in standard units. (See documentation on the Property Units Dialog for additional details on changing property units.)

The units set via the Set Property Units dialog, accessed either from the Options menu's Set Units command or clicking on the Units control in a physical property field, are assigned for all documents in the application. For example, if you have three knowledge base documents open and then change the units of the critical temperature, all documents will update their critical temperature displays using the newly selected units.

Units are also stored in the application. The next time Cranium or Synapse starts, the set of units used in your last session will be used again.

Topic	Description
Estimating Chemical Properties	a short video demonstrating how to estimate physical properties using either Synapse or Cranium.
Getting Started using Cranium	provides a quick tour of Cranium's capabilities including physical property estimation and a discussion of structure editing.
Chemicals Chapter	the chemicals chapter contains numerous sections for entering and displaying data and estimates including the chemical structure section.