University:
Saint Louis University
Course:
CHEM 1030 | Fundamentals of Chemistry
Academic year:

2024
Views:

173

Pages:

2
Author:

Shaina Asuncion

Isotopes The word isotope was derived from Greek words isos and topos which means “the same place”. Isotopes variants of an element are still found in the same location in the periodic table of elements. This term was introduced by a British Chemist Frederick Soddy. What is the Nature of Isotopes? Isotopes are atoms of the same element that have the same number of protons but differ in the number of neutrons. For example, the most common oxygen isotope has 8 neutrons inside the nucleus, but other isotopes have 9 or 10 neutrons. Example: the isotope of CARBON FIRST, LOOK IN YOUR PERIODIC TABLE FOR THE ATOMIC MASS OF CARBON OR ANY ELEMENT YOU WISH AND ROUND IT INTO A WHOLE NUMBER SECOND, THE ATOMIC NUMBER (NOTE: ATOMIC NUMBER IS THE SAME AS THE PROTON AND ELECTRON) THIRD, USE THE FORMULA (# of atomic mass - #of proton = # of neutron) This is how you compute for the isotope of a compound 1. Identify the Isotopes Determine the elements: Identify all the elements present in the compound's Example: For example, chlorine has two stable isotopes: 35Cl chemical formula. and 37Cl, with abundances of Find isotopic information: For each element, find the masses and natural approximately 75.8% and abundances of its isotopes. This information is usually available in periodic 24.2%, respectively. tables or online resources. 2. Calculate the Isotopic Distribution of Each Element: For each isotope:Multiply the fractional abundance (percentage divided by 100) by the mass of the isotope. Sum the results:Add up the results for all isotopes of that element to get the average atomic mass of the element. Example:For chlorine: (35 * 0.758) + (37 * 0.242) = 35.48 amu (average atomic mass of chlorine) 3. Combine the elemental distributions to get the compound's distribution: Consider stoichiometry: The stoichiometry of the compound (the number of atoms of each element in the chemical formula) influences the overall distribution. Use binomial expansion or similar methods.For simple compounds, a binomial expansion can be used to calculate the probabilities of different isotopic combinations. Isotope Chlorine-35 Chlorine-37 Mass number Number 35 37 Atomic Mass Unit Percentage Abundance 34.969 36.966 75.53% 24.47% Relative Atomic Mass 35.45 Important Isotopes Isotope Use/s Sodium-24 Injected into limb to detect blood cloth Cobalt-60 Detect and Treat Cancer/ use to kill bacteria Iodine-131 Detect functions of Thyroid Gland Phosphorous- Added to fertilizer to study plant processes 32 Nitrogen-15 Added to fertilizer to study plant processes Cesium-137 Use to kill bacteria Flourine-18 Use for diagnosis and treatment of diseases Gallium-67 Use for diagnosis and treatment of diseases Carbon-14 Carbon dating Process

Isotopes and Their Uses

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