Three Ways to Represent a Reaction
Introduced| English |
|---|
| macroscopic/ˌmækrəˈskɒpɪk/ |
| particulate/pəˈtɪkjʊleɪt/ |
| symbolic/sɪmˈbɒlɪk/ |
One event, three viewpoints
- Watch magnesium burn -- a bright flash and white ash.
- Zoom in and you would see atoms rearranging.
- Write it down and it becomes a tidy equation.
- The same event can be told in three languages.
The macroscopic view
- The macroscopic 宏观 level is what you see, feel, and measure.
- Colour, bubbles, temperature, mass -- the lab observations.
- It is the everyday, hands-on picture.
Observing bubbles and a temperature rise is which level?
What you directly see and measure is the macroscopic level.
The particulate view
- The particulate 微粒 level shows the atoms and molecules themselves.
- Particle diagrams reveal how they rearrange.
- It explains why the macroscopic change happens.
A diagram of individual atoms rearranging is which level?
The particulate level shows the actual atoms and molecules.
The particulate view gives the ____ for the macroscopic observations.
Rearranging atoms explains why the observed change occurs.
The symbolic view
- The symbolic 符号 level is the chemical equation.
- Formulas and coefficients summarize the whole thing.
- A good chemist moves fluently between all three.
Three ways to see a reaction
Sort each description by the level chemists are working at.
The equation $\text{C} + \text{O}_2 \to \text{CO}_2$ is which level?
Formulas and coefficients are the symbolic representation.
Match each description to its level.
Observations = macroscopic, atoms = particulate, equation = symbolic.
Burning carbon: $\text{C} + \text{O}_2 \to \text{CO}_2$.
- Macroscopic: the coal glows and gives off heat.
- Particulate: one carbon atom bonds with one $\text{O}_2$ molecule.
The three levels describe the same single event.
They are three views of one reaction, not three different reactions.
The three levels describe the same event, not three different things -- always connect them. The symbolic equation's coefficients must match the particulate counts of particles. And macroscopic observations are the evidence, while the particulate view is the explanation.
A reaction can be told three ways: the macroscopic view (what you observe), the particulate view (the atoms rearranging), and the symbolic view (the equation). They all describe one event -- coefficients match particle counts, and the particulate picture explains the macroscopic evidence.