Source code:
@Grab(group='org.openscience.cdk', module='cdk-bundle', version='2.9')
import org.openscience.cdk.interfaces.*;
import org.openscience.cdk.*;
IAtom atom = new Atom("C");
atom.setAtomTypeName("C.3")
atom.setFormalCharge(-1)
atom.setMaxBondOrder(IBond.Order.SINGLE)
atom.setFormalNeighbourCount(4)
Output: