Which of these is NOT a subatomic particle found in an atom?
Rules & what counts
Odd One Out: Periodic Table — Rules & What Counts
Four options, one impostor — chemistry edition. Each round names a category from the periodic table ("Which of these is NOT a noble gas?") and shows four candidates; tap the one that doesn't fit. Rounds sweep across noble gases, halogens, alkali metals, room-temperature states, radioactivity and a round of straight-up fake elements.
The traps lean on near-misses: nitrogen sits right next to the noble gases and behaves almost as lazily; silicon shines like a metal but isn't one; and Adamantium has convinced a generation of Marvel fans it's on the table somewhere. Every round ends with a one-line explanation, so each miss files the fact away properly.
How to play
Read the question. Then tap the option that does not belong.
You get one pick for each round. There are no second guesses.
The quiz marks your answer immediately. It also gives one line that explains the answer.
You start with three lives. The hearts in the top bar show the lives that you have.
A correct answer gives one point. A wrong answer costs one life.
A round that costs a life gives no points. The quiz continues with the next round.
The run ends when you lose the third life. It also ends when you play all the rounds.
Select "Review rounds" on the result screen to see each round that you played.
What counts in this quiz
The quiz holds 100 periodic-table categories. One run can use all of them, reshuffled each play.
Categories follow standard chemistry: IUPAC group membership, room-temperature states at standard conditions, elements with no stable isotopes for the radioactivity round.
Your score is the number of correct answers. The maximum score is 100 — every round in the quiz.
A wrong answer costs one life. You keep the points that you have.
The timer counts up from your first pick. It only separates equal scores on the leaderboard.
What's not included — and why
No borderline cases — elements whose classification is genuinely disputed are simply not used on either side of a round.
No trick isotopes — the radioactivity round is about the element as found in nature, not exotic lab isotopes.
Good to know
Bromine and mercury are the only two elements that are liquid at room temperature.
Marie Curie named polonium after her homeland Poland — hoping the name would draw attention to Poland's fight for independence.
Dmitri Mendeleev predicted gallium and germanium before anyone found them — he left gaps in his 1869 table and described the missing elements' properties in advance.