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Author: jlovering
No. Questions: 5
Created: Oct 13, 2016
Last Modified: 3 years ago

Chemistry Target 1.2

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Distinguish between atomic number and mass number and relate both to nuclear particles and explain the fundamental role of the proton and atomic number in element identity
Grade 10 Atomic Structure
Thallium has two isotopes, thallium-203 and thallium- 205. Thallium's atomic number is 81, and its atomic mass is 204.38 amu. Which statement about the thallium isotopes is true?
  1. There is more thallium-203 in nature.
  2. Atoms of both isotopes have 81 protons.
  3. Thallium-205 atoms have fewer neutrons.
  4. The most common atom of thallium has a mass of 204.38 amu.