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Two isotopes of uranium are U-235 and U-238 - Edexcel - GCSE Physics - Question 3 - 2012 - Paper 1
Question 3
Two isotopes of uranium are U-235 and U-238. Here are the symbols of the nuclei of these isotopes. (i) Complete the sentence by putting a cross (X) in the box next... show full transcript
Worked Solution & Example Answer:Two isotopes of uranium are U-235 and U-238 - Edexcel - GCSE Physics - Question 3 - 2012 - Paper 1
Step 1
Complete the sentence by putting a cross (X) in the box next to your answer.
Answer
The U-235 isotope has C. more neutrons than U-238.
*Explanation: U-235 has 143 neutrons (235 - 92) whereas U-238 has 146 neutrons (238 - 92). Hence, U-235 has fewer neutrons than U-238, making the correct answer B, as they have the same number of protons (92).
Step 2
Describe an alpha particle.
Answer
An alpha particle consists of 2 protons and 2 neutrons, which is essentially the nucleus of a helium atom. It has a positive charge due to the presence of protons.
Characteristics of alpha particles:
- They are relatively large and heavy compared to other types of radiation.
- They can be stopped by a sheet of paper or a few centimeters of air, indicating low penetration power.
- When emitted during radioactive decay, alpha particles can result in a decrease in atomic number and mass of the original atom.