neighbouringElementsEqual(arr) {
    if (arr.length !== this.neighbouringElements.length) {
      return false;
    }

    arr.sort();
    this.neighbouringElements.sort();

    for (var i = 0; i < this.neighbouringElements.length; i++) {
      if (arr[i] !== this.neighbouringElements[i]) {
        return false;
      }
    }

    return true;
  }
Check whether or not the neighbouring elements of this atom equal the supplied array.

@param {String[]} arr An array containing all the elements that are neighbouring this atom. E.g. ['C', 'O', 'O', 'N']
@returns {Boolean} A boolean indicating whether or not the neighbours match the supplied array of elements.