Which new characteristic did John Dalton introduce to the atomic model?

• A. Atoms of each element are identical in mass and properties
• B. Atoms can be divided into protons, neutrons, and electrons
• C. Atoms contain negatively charged electrons
• D. Atoms have a dense, positively charged nucleus

Answer: (A)

Verified step by step guidance

1. Understand the historical context of atomic models before John Dalton, which mainly involved the idea that matter is composed of indivisible particles called atoms but lacked detailed characteristics about these atoms.
2. Recall that Dalton's atomic theory introduced the concept that atoms of a given element are identical in mass and properties, distinguishing them from atoms of other elements.
3. Recognize that Dalton did not propose the internal structure of atoms (such as protons, neutrons, electrons) or the existence of a nucleus; these ideas came later with other scientists.
4. Focus on Dalton's key contribution: the idea that each element consists of atoms that are identical in mass and properties, which laid the foundation for understanding chemical reactions as rearrangements of these atoms.
5. Summarize that the new characteristic introduced by Dalton is that atoms of each element are identical in mass and properties, differentiating his model from earlier, more vague concepts of atoms.