وَمَا تَكُونُ فِي شَأْنٍ وَمَا تَتْلُو مِنْهُ مِن قُرْآنٍ وَلَا تَعْمَلُونَ مِنْ عَمَلٍ إِلَّا كُنَّا عَلَيْكُمْ شُهُودًا إِذْ تُفِيضُونَ فِيهِ وَمَا يَعْزُبُ عَن رَّبِّكَ مِن مِّثْقَالِ ذَرَّةٍ فِي الْأَرْضِ وَلَا فِي السَّمَاءِ وَلَا أَصْغَرَ مِن ذَٰلِكَ وَلَا أَكْبَرَ إِلَّا فِي كِتَابٍ مُّبِينٍ
And, [O Muhammad], you are not [engaged] in any matter or recite any of the Qur'an and you [people] do not do any deed except that We are witness over you when you are involved in it. And not absent from your Lord is any [part] of an atom's weight within the earth or within the heaven or [anything] smaller than that or greater but that it is in a clear register.
Qur'an 10:61; other English translations are at Islam Awakened
The relevant Arabic words are (translations from Wiktionary):
Clearly the word ذرة in the Qur'an predates atomic theory, which began scientific development circa 1800. This leads me to my question:
Question: How did "an atom's weight" come to be mentioned in translations of the Qur'an?
- Qur'an 99:7-8, So whoever does an atom's weight of good will see it, And whoever does an atom's weight of evil will see it.;
- Qur'an 4:40, Allah does not do injustice, [even] as much as an atom's weight;
- Qur'an 34:3, Not absent from Him is an atom's weight within the heavens or within the earth or [what is] smaller than that or greater, except that it is in a clear register; and
- Qur'an 34:22, They do not possess an atom's weight [of ability] in the heavens or on the earth.
- Sahih al-Bukhari, which describes Qur'an 99:7-8 being revealed, although this translation says weight of an atom (or a smallest ant);
- Muwatta Malik, A'isha said, 'Are you amazed? How many atoms' weights do you see in this grape?' " (referring to Sura 99 ayat 7).
There's probably other sources I have not found.
Searching the Islam-critical site WikiIslam.com for
atom did not yield anything relevant; they usually have pages for "debunking" claims of miracles in the Qur'an.
(Meta comment: I proposed this as a draft question (here), although I feel like I've mostly answered it in researching the topic. Thus, I'll post that as an answer below. Perhaps someone can give a better answer.)