Atom_NumHydrogens Property

CDXML Name:NumHydrogens
CDX Constant Name:kCDXProp_Atom_NumHydrogens
CDX Constant Value:0x042B
Data Size:UINT16
Property of objects:kCDXObj_Node
First written/read in:ChemDraw 4.0 / 6.0


The number of (explicit) hydrogens in a labeled atom consisting of one heavy atom and (optionally) the symbol H (e.g., CH3).

As for an example, an atom with the label "Si" with bonds to CH3, CH3, H, and H has no explicit hydrogen (the Hs are represented as distinct nodes), and this attribute is not required. On the other hand, the same element node has two explicit hydrogens if it is labeled "SiH2" with two bonds to CH3 and CH3.

This property is meaningful only for nodes with a kCDXProp_Node_Type of type Element.

If this property is absent:

The number of hydrogens is assumed to be the minimum value necessary to satisfy the valence requirements for the atom.


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