"I messed up..."
In the laboratory, Toma stared at a solution that had turned blue.
"What did you add?" Kana rushed over.
"It was supposed to be just vitamin C... but when I added it to iodine solution, the color disappeared."
Rei calmly peered into the notebook. "A reduction reaction. Electrons moved."
"Electrons moved? What do you mean?" Kana tilted her head.
Rei began drawing a simple diagram. "The essence of chemical reactions is the exchange of electrons. Vitamin C gave electrons, and iodine received them."
"But why do electrons move?"
"Because the electrons' 'comfort level' differs. Different atoms have different powers to attract electrons."
Toma said as if remembering. "Electronegativity? We learned about it in chemistry!"
"Yes. Iodine has higher electronegativity, so it can snatch electrons. That's a redox reaction."
Kana wrote in her notebook. "I thought oxidation meant combining with oxygen."
"Originally, yes. But the essence is electron transfer. Losing electrons is oxidation, gaining them is reduction."
Rei showed another example. "Iron rusting is also oxidation. Iron atoms lose electrons and become iron ions."
"Then where do those electrons go?"
"Oxygen receives them. Oxygen is reduced."
Toma got excited. "So oxidation and reduction are a set!"
"Exactly. One cannot happen without the other. Electron exchange always comes in pairs."
Kana looked around the experiment table. "Then electrons are flying around everywhere in this room?"
Rei nodded. "Respiration also involves electron movement through the electron transport chain. We extract electrons from food nutrients and eventually pass them to oxygen."
"Are electrons that important?"
"They're the currency of energy. When electrons move from high-energy molecules to low-energy ones, we can use that energy difference for life activities."
Toma stared at the vitamin C bottle. "Does vitamin C also give away electrons inside the body?"
"Yes. That's why it's called an antioxidant. To prevent harmful oxidation reactions in the body, it gives away electrons first."
"A substitute?" Kana was surprised.
"In a sense. It protects cells from unstable molecules called free radicals."
Rei drew the electron flow on the whiteboard. Arrows crossing in complex patterns.
"Most biochemical reactions involve electron transfer. Photosynthesis, cellular metabolism."
Kana's eyes sparkled. "Even though they're small, electrons move the world."
"It's quantum-level stuff, but its effects extend to the macro level."
Toma looked at the solution again. The color was starting to return.
"Huh? It's turning blue again?"
Rei explained. "Oxygen in the air is snatching electrons again. It's a reversible reaction."
"Like a tug-of-war with electrons," Kana laughed.
"Exactly. Redox is a competition over electrons."
Toma's face became serious. "Then every time we eat and breathe, we're doing electron tug-of-war."
"Living is controlling electrons," Rei said quietly.
The three stared at the solution. The color fluctuated, changed, and returned. It felt like watching the journey of electrons right before their eyes.
"Chemistry is really alive," Kana murmured.
A quiet empathy spread through the laboratory.