Ratio of neutrons to protons in lead-206 and uranium-238. In which nucleus is the ratio closer to 3:2?
To find the ratio of neutrons to protons in an atomic nucleus, you need to know the atomic number and the mass number. The atomic number gives you the number of protons, while the difference between the mass number and the atomic number gives you the number of neutrons.
Let's start with lead-206 (Pb-206). The atomic number of lead is 82, which means it has 82 protons. The mass number of Pb-206 is 206. So the number of neutrons is calculated by subtracting the atomic number from the mass number:
Neutrons = Mass number - Atomic number
Neutrons = 206 - 82
Neutrons = 124
Therefore, lead-206 (Pb-206) has 124 neutrons and 82 protons.
Now let's move on to uranium-238 (U-238). The atomic number of uranium is 92. The mass number of U-238 is 238.
Neutrons = Mass number - Atomic number
Neutrons = 238 - 92
Neutrons = 146
Therefore, uranium-238 (U-238) has 146 neutrons and 92 protons.
To compare the ratios, we divide the number of neutrons by the number of protons for each nucleus:
Ratio for Pb-206 = Neutrons / Protons
Ratio for Pb-206 = 124 / 82
Ratio for Pb-206 ≈ 1.51
Ratio for U-238 = Neutrons / Protons
Ratio for U-238 = 146 / 92
Ratio for U-238 ≈ 1.59
So, the ratio of neutrons to protons is closer to 3:2 in lead-206 (Pb-206), since its ratio is approximately 1.51, which is closer to 3/2 (1.5) than the ratio for uranium-238 (U-238), which is approximately 1.59.