text: // Electrons are associated with orbitals,
  export default class {
    constructor(orbitalId, idNumber, radius=3, color='black') {
      this.orbitalId = orbitalId
      this.radius = radius
      this.color = color
      this.eId = orbitalId + '-' + 'electron-' + idNumber
      // materialize electron (could be method)
      return d3.select('#' + this.orbitalId).append("circle")
                                      .attr("r", this.radius)
                                      .attr("class", "bohr-electron")
                                      .attr("id", this.eId)
                                      .style("fill", this.color)
    }
  }
  