Atomic structure and isotopesEdexcel International A Level Chemistry: Mind map

Exam questions on Atomic structure and isotopes

1. A thyroid clinic uses iodine-131, a radioactive isotope, to treat an overactive thyroid gland. Naturally occurring iodine is entirely stable iodine-127. Iodine has atomic number 53.
   Explain why iodine-131 and iodine-127 have the same chemical properties but different masses.2 marks
2. A physics demonstration passes separate beams of protons, neutrons and electrons between two electrically charged metal plates. The beams are deflected by different amounts, or not at all.
   Explain why a neutral atom has no overall charge, and why almost all of its mass is in the nucleus.2 marks
3. Magnesium (atomic number 12) occurs naturally as three isotopes: ²⁴Mg, ²⁵Mg and ²⁶Mg.
   Explain what is meant by the term isotopes, using ²⁴Mg and ²⁶Mg as examples.3 marks