Guess the Chemidle in six tries! Which is a chemical equation.

This chemical equation contains only the first 20 elements in the periodic table, with coefficient(s) not greater than 6. The length of the equation is not fixed, with number of tokens no more than 15. The reaction conditions and reaction phenomena are ommitted.

After each guess, the color of the tokens will indicate the target chemical equation: grey indicates not exist; yellow indicates existence but in wrong place; green indicates correctness.

Each guess must contain one → symbol, and the number of atoms must be balanced in both sides.

When a whole row is green, congraduations, you win!