To change the charge state or isotope of an atom, or to change the element entirely, use the Atom Properties dialog box.

To open the Atom Properties window, use one of the following methods:

• Select the Atom Properties  button in the Structure Editor window and then click the atom you want to change.
• Or restore defaults, and then double-click on the atom you want to change.

In the Atom Properties dialog window, you can make the changes by clicking the appropriate element button, charge and radical check box, or nucleon number edit box.

Note: All changes carried out in the Atom Properties dialog window will only affect a single atom.

If you wish to change an element that has a single character symbol, i.e. C, H, N, O, B, F, K, P, S, I, V, W, Y, U and R; a faster method is available:

• Select all the atoms that you want to change and press the appropriate key on the keyboard. All the selected atoms will be transformed into the element you have chosen.

Chlorine (Cl) or bromine (Br) atoms can be set in a similar manner:

• Select all the atoms that you want to change and press either the C (for chlorine) key or B (for bromine) key on the keyboard, while holding down the SHIFT key.

It is possible to use a substituent instead of a specific element. The symbol ”R” represents a substituent. A substituent can be with or without index. Substructure search and fragments generation algorithms consider substituents with identical indexes as equal and substituents with different indexes as not equal. When searching structures with substituents, please note the search rules that apply.