Volume 2 Chapter 1 Build Menu ELEMENT TYPES

Function

These options are used to specify the element type of an atom.

Remarks

The "Current Element" is the default element assigned to newly generated atoms. It is always displayed in the bottom right-hand corner of the menu box which contains element symbols.

You can change the Current Element as follows:

(i): select one of the 8 most common elements in the database viz. C, N, O, S, P, Cl, Br, F.
(ii): select OTHER to replace the BUILD menu by the PERIODIC-TABLE sub-menu, then select the appropriate element or element group.
(iii): select the Current Element box, then type the new element symbol.

Note that, in MOVE mode, if the element symbol of a selected atom is different from the Current Element symbol then the atom selected is assigned the Current Element symbol.

Example

On entry to the BUILD menu the current element type is carbon.

This is indicated - see below - by the symbol C in the second red box down on the right hand side.

The 8 most common elements, excluding H, in the database are C, N, O, S, P, Cl, Br, F. These symbols are displayed in lines a and b.

To change the element type from the default C to N

Select N
Now the red box on line c contains N.
For all other elements and combinations of elements we use the menu option OTHER on line c.
Select OTHER
The BUILD menu vanishes and is replaced by the PERIODIC-TABLE sub-menu - see below.
Select As
The PERIODIC-TABLE sub-menu vanishes and is replaced by the BUILD menu.
The current element box now contains As.

The various group and period symbols in the PERIODIC-TABLE sub-menu are given in Appendix 1. To remind users of the special groupings:

8B = 8X + 8Y + 8Z

TR = 1R + 2R + 3R + Ac

LN = La, Ce, Pr, ... ,Yb, Lu

AN = Ac, Th, Pa, ... ,No,Lw

1M = 1A + 2A

2M = Al, Ga, In, Tl, Ge, Sn, Pb, Sb, Bi, Po

3M = 1M + 2M

4M = 1M + 2M + LN + AN + TR

HD = H or D

AA = any element.

Note that by clicking in the current element box and responding to the prompt, the PERIODIC-TABLE sub-menu can be bypassed and any element, group or ELDEF (see later) symbol may be typed.

Click current element box

Use keyboard to type new default ELEMENT symbol. Then press <RETURN>.

Type Fe <Return>
Current element box now contains Fe.

If the groups of elements explicitly afforded by the PERIODIC-TABLE sub-menu are not adequate then the user can set up special groups using the ELDEF feature. This will be illustrated by two examples.

Ex. 1 Suppose we wish to build the fragment, where RR = Se or Te:

Then we might build the fragment:

Select OTHER
The BUILD menu vanishes and is replaced by the PERIODIC-TABLE sub-menu - (i) below.
(i)
Select ELDEF

Please type the NEW ELEMENT SYMBOL
(Press <RETURN> if you don't want a new symbol)

Type RR <R>

The new element box appears at x - see (ii) - with the symbol RR in it.
(ii)
The + at position y is now active.

Select a symbol or command.
Select "=" to end definition, or CANCEL to quit.

Select Se
Select Te
Select =
The program then prompts:

Select the new box to make it the Current Element in the BUILD
menu.

Select RR in the new element box at position x

The PERIODIC-TABLE sub-menu vanishes and is replaced by the BUILD menu.
The current element box now contains RR.
Select atom a
The fragment is now:

Ex. 2 Suppose we wish to build the fragment (i) - see below.

We could proceed as in Ex. 1 but we will, instead, use the minus (-) feature of ELDEF.

Then we might build the fragment (ii).

Select OTHER
The BUILD menu vanishes and is replaced by the PERIODIC-TABLE sub-menu.
Select ELDEF

Please type in the NEW ELEMENT SYMBOL
(Press <RETURN> if you don't want a new symbol)

Type MM <R>
The new element box appears and contains the symbol MM.
+ is now active.

Select a symbol or command.
Select "=" to end definition, or CANCEL to quit.

Select 8Y
Co, Rh, Ir are all now active.

Select a symbol or command.
Select "=" to end definition, or CANCEL to quit.

Select -
+ is now inactive and - is active.

Select a symbol or command.
Select "=" to end definition, or CANCEL to quit.

Select Co
Rh and Ir are now active, Co is inactive.

Select a symbol or command.
Select "=" to end definition, or CANCEL to quit.

Select =

The program then prompts:

Select the new box to make it the Current Element in the BUILD
menu.

Select MM in the new element box.
The PERIODIC-TABLE sub-menu vanishes and is replaced by the BUILD menu.
The current element box now contains MM.
Select atom a
The fragment is now as in (iii).

You should note the following points relating to the use of ELDEF:

(a)

The new element symbol can be one or two characters:

the first must be alphabetic

the second must be alphabetic or a blank character.

Please type the NEW ELEMENT SYMBOL
(Press <RETURN> if you don't want a new symbol)

Type J2 <R>

Invalid syntax for ELEMENT symbol. Please use only alphabetic
characters.
Please press <RETURN> to continue. Thank you.

(b)

In the same session you can use more than one new element symbol e.g. MM, NN, OO, PP, RS, etc.

Suppose you have defined MM and at a later stage you select OTHER. When the PERIODIC-TABLE sub-menu appears on the screen then the new element box containing MM is displayed.

If you define a new element NN then a second new element box will appear, containing NN.

Note, however, that you cannot re-use a symbol in a later new element definition. Thus, suppose we have defined MM and then later we select OTHER.

Select ELDEF

Please type the NEW ELEMENT SYMBOL
(Press <RETURN> if you don't want a new symbol)

Type MM <R>

This symbol is already used for an element or definition. Please re-type.
Please type the NEW ELEMENT SYMBOL
(Press <RETURN> if you don't want a new symbol)

(c)
If you find that in many sessions you are using the same set of ELDEF's then you should consider saving them using the STORE-FRAGMENT command in the FILES menu.
There is no need to have a fragment on the screen - simply generate your ELDEF's, then

Select TO-FILES
Select STORE-FRAGMENT
VAX/VMS users should read the appropriate notes in Appendix 12.

Each time you begin a session and want to retrieve these ELDEFs:

Select TO-FILES
Select FETCH-FRAGMENT

Currently in the VAX/VMS version, the ELDEF-containing fragment appears on the FETCH-FRAGMENT display as a blank box. However, if this box is selected, the ELDEFs are written into the BUILD OTHER display and can be selected and used in the current session.

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