class Element extends ChemObject implements Serializable, IElement, Cloneable {

    @Override
    public String getSymbol() {
        if (atomicNumber == null)
            return null;
        if (atomicNumber == 0)
            return "R";
        return Elements.ofNumber(atomicNumber).symbol();
    }

    public  Element();
    public  Element(IElement element);
    public  Element(String symbol);
    public  Element(String symbol, Integer atomicNumber);

}