CHEM101 Lecture Notes - Lecture 1: Unified Atomic Mass Unit, Paramagnetism, Magnetic Quantum Number

• School: University of Alberta
• Department: Chemistry
• Course: CHEM101
• Professor: Sai Yiu

Document Summary

Mass number (a) is the number of protons + number of neutrons in the nucleus. Atomic number (z) is the number of protons in the nucleus of that atom. Isotopes are different atoms of the same element that have different numbers of neutrons but with the same number of protons ie) 16o 17o 18o. Examples: gallium has two naturally occurring isotopes, 69ga (isotopic mass 68. 9256 amu, abundance 60. 11%) and 71ga (isotopic mass 70. 9247 amu, abundance 39. 89%). Atomic mass of gallium = (68. 9256 amu x 0. 6011) + (70. 9247 amu x 0. 3989) = 69. 72 amu: boron (z = 5) has two naturally occurring isotopes: 10b and 11b. If the atomic mass of boron is 10. 81 amu and the isotopic mass of 10b = 10. 0129 amu and 11b = 11. 0093 amu, calculate the natural abundance of each isotope. Let the natural abundance of 10b = x the natural abundance of 11b would be = (1 x)