1) Dalton stated that atom is matter that can not be divided, but it is proved that the atom can be divided into subatomic particles (electrons, protons and neutrons).
2) He stated that atoms of one element can not be changed into atoms of other elements, but now that is possible by nuclear reactions.
Today we still use his postulate: Atoms combine in the ratio of small whole numbers to form stable compounds, for example H₂O.
Answer:
The answer to your question is: 55.84 u. The element is Iron
Explanation:
isotope 1 mass 53.94 u abundance 5.85%
2 mass 55.9349 abundance 91.75%
3 mass 56.9354 abundance 2.12%
4 mass 57.9333 abundance 0.28%
average atomic mass = (53.94 x 0.0585) + (55.9349 x 0.9175) + (56.9354 x 0.0212) + (57.9333 x 0.0028)
average atomic mass = 3.155 + 51.32 + 1.207 + 0.1622
average atomic mass = 55.84 u. The element is Iron