Which Concept In Dalton'S Atomic Theory Has Been Modified

Question:

Answer: b. The number of protons in an atom is its atomic number.

Question:

Answer: d. all atoms of the same element have the same mass.

Question: Which of the following statements is true?

1. Atoms of the same element may have different masses.

2. b. Atoms may be divided in ordinary chemical reactions.

3. c. Atoms can never combine with any other atoms.

4. d. Matter is composed of large particles called atoms.

5. Answer: a. Atoms of the same element may have different masses.

6. Question: Which concept in Dalton’s atomic theory has been modified?

7. Answer: Atoms cannot be divided.

8. Question: In Rutherford’s experiments, positively charged particles

9. Answer: were used to bombard thin metal foil.

10. Question: Because a few positively charged particles bounced back from the foil, Rutherford concluded that such particles were

11. Answer: repelled by densely packed regions of positive charge.

12. Question: The nucleus of an atom has all of the following characteristics EXCEPT that it

13. a. is positively charged. c. contains nearly all of the atom’s mass.

14. b. is very dense. d. contains nearly all of the atom’s volume.

15. Answer: contains nearly all of the atom’s volume.

16. Question: The nucleus of most atoms is composed of

17. Answer: tightly packed protons and neutrons.

18. Question: The smallest unit of an element that can exist either alone or in combination with other such particles of the same or different elements is the

19. Answer: atom

20. Question: Helium-4 and helium-3 are

21. Answer: isotopes