Logic Masters Deutschland e.V.

Happy Holidays! I hope you enjoy this chemistry-themed puzzle. (I am a chemistry professor, so I wanted to try setting one like this.)

Rules

Normal sudoku rules apply. The grid is a box of gas containing six helium atoms and four water molecules. Like all gas particles, these ten atoms/molecules are positioned far away from each other. Specifically, different atoms/molecules never share cells or occupy neighboring cells, even diagonally. Among the "empty spaces" in the box (i.e., cells not occupied by atoms/molecules), there is a hidden Dutch Whisper line connecting the marked R1C1 and R9C9 cells. The Dutch Whisper line travels orthogonally (not diagonally) between neighboring cells, and includes exactly four distinct digits. The Dutch Whisper line must travel through the black dot, which connects a pair of digits where one is double the other.

• Helium atom: The digit 2, shaded blue.
• Water molecule: An orthogonally connected "oxygen atom" that sums to 8 (which may include repeats), shaded red - and two "hydrogen atoms" (1's, shaded gray) that are orthogonally adjacent to the oxygen. Given digits that are shaded red are part of oxygen atoms. Other given digits may or may not be part of atoms/molecules.
• Dutch Whisper line: Adjacent digits on the line must differ by at least 4.

For clarity, a helium atom and examples of water molecules are shown here: