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The element antimony (Sb) has at least 29 known isotopes - VCE - SSCE Chemistry - Question 7 - 2003 - Paper 1
Question 7
The element antimony (Sb) has at least 29 known isotopes. Only two of these are stable isotopes that occur naturally; the other 27 isotopes are radioactive and have ... show full transcript
Worked Solution & Example Answer:The element antimony (Sb) has at least 29 known isotopes - VCE - SSCE Chemistry - Question 7 - 2003 - Paper 1
Step 1
What operations occur in stages 1 and 3?
Answer
Stage 1
The operation in stage 1 is the ionisation of the antimony samples, which involves vaporization and subsequent ionization typically through electron bombardment. This process converts the neutral atoms into positively charged ions.
Stage 3
In stage 3, the ions produced are deflected based on their mass-to-charge ratio in an electric or magnetic field. This separation allows for the identification of different isotopes.
Step 2
Step 3
How is deflection achieved in stage 4?
Answer
Deflection in stage 4 is achieved by subjecting the ions to a magnetic or electric field. The field influences the trajectory of the ions, causing them to curve according to their mass-to-charge ratio, thus allowing separation based on these properties.
Step 4
What information can be obtained from a mass spectrometer about naturally occurring antimony?
Answer
A mass spectrometer provides essential information about the isotopes present in naturally occurring antimony, including:
- The relative masses of each isotope, allowing us to identify them.
- The relative abundance of each stable isotope, which indicates the isotopic composition of naturally occurring antimony.
Step 5
From the data given, calculate the percentage abundance of each of the stable isotopes of naturally occurring antimony.
Answer
To calculate the percentages, we start with the relative atomic mass of naturally occurring antimony, which is 121.75. Let (x) be the fractional abundance of (^{123}Sb) and (1 - x) for (^{121}Sb). The equation based on the average is:
Solving for (x):
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Distribute: (120.903 - 120.903x + 122.9041x = 121.75)
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Combine like terms: (1.0011x = 0.8462)
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Solve for (x): ( x = 0.8462 / 1.0011 \approx 0.845)
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Therefore:
- The abundance of (^{123}Sb) is approximately 84.5%.
- The abundance of (^{121}Sb) is (100% - 84.5% = 15.5%).
Step 6
Step 7
How many neutrons are there in the nucleus of the \(^{121}Sb\) isotope?
Answer
The (^{121}Sb) isotope has a mass number of 121 and an atomic number of 51. The number of neutrons can be calculated by subtracting the atomic number from the mass number:
Thus, there are 70 neutrons in the nucleus of the (^{121}Sb) isotope.
Step 8
Give the symbol of the atoms produced from the decay process of each of the given radioactive isotopes.
Answer
i. (^{125}Sb \rightarrow ^{125}Te + e^-)
In this decay, (^{125}Sb) transforms into tellurium (^{125}Te) by emitting a beta particle (an electron).
ii. (^{123}Sb \rightarrow ^{123}I + e^+)
In this decay, (^{123}Sb) transforms into iodine (^{123}I) by emitting a positron.