After 8 years teaching college-level chemistry, I can tell you this with certainty: most students lose points not because they don’t know the material, but because they don’t know what “correct” looks like from a grading perspective.
The gap between a student who understands the chemistry and a student who earns full credit for that understanding is smaller than you’d think — and it’s almost entirely about presentation and precision.
First: how professors actually grade
A typical gen chem professor grades 80 to 150 exams in a day or two. They’re looking for specific things in a specific order. When those things are present and clearly visible, you get the points. When they’re buried in unclear work or missing entirely, you don’t — even if the underlying understanding is there.
This isn’t unfair grading. It’s the reality of how chemistry (and chemistry careers) work. A lab report or a research calculation that’s missing units or unexplained reasoning isn’t just incomplete — it’s potentially wrong in a way that matters.
The 4 things professors are actually looking for
1. Units on every number
A number without a unit is an incomplete answer. Full stop. It doesn’t matter if the arithmetic is perfect — if you write “4.2” instead of “4.2 mol/L,” that answer is wrong on most rubrics. This is one of the easiest points to lose and one of the easiest to protect.
2. The reasoning, not just the answer
When a question says “explain,” it means: state what happens and the chemical reason why. “The reaction shifts right” is not an explanation. “The reaction shifts right because the added reactant increases Q above K, so the system responds by consuming reactants to restore equilibrium” is.
The answer tells the professor what you concluded. The reasoning tells them whether you understood the chemistry or got lucky.
3. Significant figures
Wrong sig figs signal to a professor that you don’t understand measurement precision — and that matters in chemistry. The rule is simple: your answer should have the same number of sig figs as the least precise value you were given. Consistently ignoring this costs points on every calculation question.
4. Organized, readable work
Professors grade dozens of exams at a time. Clear, stepwise work gets the benefit of the doubt when there’s ambiguity. Messy work that arrives at the right answer still gets the right answer — but if there’s an error buried in three lines of cramped calculations, the professor is less likely to hunt for partial credit.
Write one step per line. Label what each value represents. Box your final answer. This takes 30 extra seconds and protects multiple points.
What professors don’t say out loud (but notice)
- Starting with a formula and not defining variables. If you write “PV = nRT” and immediately plug in numbers without labeling them, a professor can’t tell if you knew what you were doing or just matched numbers to letters.
- Skipping steps because they seem obvious. They’re obvious to you. Show them anyway. That’s where partial credit lives.
- Writing an answer with no work. Even a correct answer with no work shown earns zero partial credit if it’s wrong — and might not earn full credit even when it’s right, depending on the rubric.
- Vague language on conceptual questions. “It goes up,” “it changes,” “it’s more stable” — these phrases tell a professor you’re guessing. Specific chemical language tells them you understand.
The one habit that fixes most of this
Before you hand in your exam, read your work as if you’re the grader. Not as the person who knows all the reasoning happening in your head — as a stranger reading it cold.
Does the work make sense without your internal monologue? Are the units there? Is each step labeled? Would someone know what you were solving for?
This takes two minutes and catches the kinds of errors that cost students a full letter grade over a semester.
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