Atom, Element, and AtomNode

Element, Atom, and AtomNode (all from scenerystack/nitroglycerin) split the model/view concerns for a single atom in a chemistry sim. Element is a set of ~17 static, immutable instances holding real physical constants (covalent radius, electronegativity, atomic weight, display color) for specific elements (H, C, N, O, ...). Atom is a lightweight, constructible-many-times wrapper around one Element that adds per-instance identity (a unique id/reference) — you construct many Atoms referencing the same Element.O static. AtomNode is the scenery view: a shaded sphere sized and colored from the wrapped Element.

import { Atom, Element, AtomNode } from 'scenerystack/nitroglycerin';

A minimal example

const oxygenAtom = new Atom( Element.O );
const oxygenNode = new AtomNode( Element.O );

// or, from a symbol string:
const hydrogenAtom = Atom.createAtomFromSymbol( 'H' );

Element

Element is not meant to be constructed directly in client code — use one of its static instances or look one up by symbol.

Member	Description
Element.H, Element.C, Element.N, Element.O, ...	Static instances for the ~17 elements nitroglycerin models (Ar, B, Be, Br, C, Cl, F, H, I, N, Ne, O, P, S, Si, Sn, Xe)
Element.elements	Array of all static instances
symbol	e.g. 'O'
covalentRadius / vanDerWaalsRadius	In picometers
electronegativity	Pauling units, null for noble gasses
atomicWeight	Atomic mass units (u)
color	Color | string used by AtomNode
Element.getElementBySymbol( symbol )	Static lookup; asserts if the symbol isn't one of the modeled elements
isSameElement( element ) / isHydrogen() / isCarbon() / isOxygen()	Identity/convenience predicates

Atom

new Atom( element: Element )

Member	Description
element	The wrapped Element
symbol, covalentRadius, covalentDiameter, electronegativity, atomicWeight, color	Unpacked from element for convenience (covalentDiameter is 2 * covalentRadius, otherwise not present on Element)
id / reference	Per-instance unique identifiers (reference is a hex counter, id is `${symbol}_${reference}`) — distinguishes two Atoms wrapping the same Element
Atom.createAtomFromSymbol( symbol )	Static convenience combining Element.getElementBySymbol and new Atom(...)
hasSameElement( atom ) / isHydrogen() / isCarbon() / isOxygen()	Delegate to the wrapped Element

AtomNode

new AtomNode( element: Element, providedOptions?: AtomNodeOptions )

AtomNode extends ShadedSphereNode (from scenerystack/scenery-phet) — it takes an Element, not an Atom, and computes a display diameter from element.covalentRadius (compressed nonlinearly so the largest and smallest modeled atoms don't differ as dramatically on screen as their real radii would suggest). mainColor defaults to element.color; any other ShadedSphereNodeOptions may be passed through and override it.

const bigOxygen = new AtomNode( Element.O );
const smallHydrogen = new AtomNode( Element.H, { mainColor: 'lightgray' } ); // override the default element color

AtomNode takes an Element, not an Atom

Since AtomNode only needs covalentRadius and color — both already on Element — it skips Atom entirely. Reach for Atom only when you need per-instance identity (e.g. tracking individual atoms in a reaction simulation); for pure rendering, construct AtomNode straight from the Element static you need.