## ISOTOPEIsotopes Definition: Isotopes are atoms with the same number of protons, but differing numbers of neutrons. Isotopes are different forms of a single element. Examples: Carbon 12 and Carbon 14 are both isotopes of carbon, one with 6 neutrons and one with 8 neutrons (both with 6 protons).
## ATOMIC WEIGHTS AND ISOTOPIC ABUNDANCEThe atomic You know that the sum of the percentages of the isotopes is equal to 1 (100%), so the relative abundance of the isotopes can be found using simple algebra.
Silver (Atomic To avoid mistakes, use “x” as the multiplier for the isotope percentage you wish to find. In this case, you want to find the percentage of the lighter isotope, so the “x” is associated with 106.90509. Since the sum of the isotopic abundance percentages is equal to 1 (100%), the formula is: 108.90470 (1 – x) + 106.90509 (x) = 107.868 Multiplying, re-arranging and condensing the above formula results in: 108.90470 – 108.90470x + 106.90509x = 107.868 – 108.90470x + 106.90509x = – 108.90470 + 107.868 – 1.9996x = – 1.0367 x = 0.5185 Therefore, the answer is 51.85 %
An imaginary element (Atomic In this case, we know the abundance of one of the isotopes. We know the percentages of the lighter isotope (42.38 %) and the percentage of the heavier isotope (x), so the percentage of the middle isotope is equal to 1 (100%) minus the other two percentages (1 – 0.4238 – x). 92.9469 (0.4238) + 93.2923 [(1-0.4238)-x] + 94.9030x = 93.7140 39.3909 + 53.7550 – 93.2923x + 94.9030x = 93.7140 93.14 + 1.6107x = 93.7140 1.6107x = 0.4217 x = 26.18 Therefore, the answer is 26.18% ## EVALUATION1. Define the following terms i. Atomic number ii. mass number iii. Isotopes iv. Isotopy 2. Determine the relative atomic mass of carbon from a sample with the followingdata.98.9% of carbon -12 and 1.1% of carbon-13.
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