CHEM 1E03 Lecture Notes - Lecture 1: Atomic Mass, Unified Atomic Mass Unit, Atomic Number

• School: McMaster University
• Department: Chemistry
• Course: CHEM 1E03
• Professor: N A

Document Summary

Temperature: kelvins (k: 1 k = 273. 15 degrees celsius. Amount of substance: moles (m) (cid:1857)(cid:1866)(cid:1871)(cid:1872)= (cid:1865)(cid:1853)(cid:1871)(cid:1871) (cid:1874)(cid:1867)(cid:1864)(cid:1873)(cid:1865)(cid:1857) The total mass of substances after a chemical reaction is the same as the total mass of substances before the reaction occurred. All samples of a compound have the same composition, i. e. the same proportions by mass of all constituent components. Atoms are composed of neutrons, protons, and electrons. Atomic number: # of electrons, and # of protons. Atomic mass: total mass of protons and neutrons in atom i. e. total # of protons and neutrons: measured in atomic mass units (amu) Protons and neutrons both have mass of ~1 amu. Atoms of the same element that have different numbers of electrons. Atoms of the same element that have the same atomic number, but different atomic masses. A unit of measure, based on avogadro"s number. Do not conduct electricity by themselves: conduct electricity when dissolved in water.