University:
Eastern Kentucky University
Course:
CHE 111 | General Chemistry
Academic year:

2022
Views:

126

Pages:

1
Author:

do3ran7ut

Unit 1: Atomic Structures and Properties Avogadro’s number — 6.022 × 1023  mol-1 ● Aka number of particles/atoms/molecules in one mole Atomic mass units (amu) : mass of an individual atom or molecule ● Average mass of 1 particle (atom or molecule) or formula unit of a substance = molar mass of that substance in grams. ● quantitative connection between mass and the # of particles that the substance contains. Mass Spectroscopy of Elements ● The mass spectrum of a sample of a single element can be used to determine the identity of the isotopes of that element and the relative abundance of each isotope in nature. ● An element’s amu can be estimated from the weighted average of the isotopic masses using the mass of each isotope and its relative abundance. Atomic Structure and Electron Configuration ● Aufbau Principle: electrons are added to the lowest subshells first ● Hund’s Rule: Each orbital should have one electron before any are doubled up ● Effective Nuclear Charge: net positive charge experienced by valence electrons. It can be calculated by Zeff = Z – S ○ Z : atomic #, S : # of shielding (core) electrons Photoelectron Spectroscopy ● energies of the electrons in a given shell can be measured ● position of each peak – Energy required to remove an electron from the corresponding subshell ● height of each peak – # of electrons in that subshell ● Photoelectric Effect: the emission, or ejection, of electron from the surface of, generally, a metal in response to incident light ● greater binding energy = electrons are closer to the nucleus Periodic Trends ● Zeff or effective nuclear charge is determined by the amount of protons and pulls electrons closer to the nucleus ● Ionization Energy: energy required to remove an electron ● Electron Affinity: The amount of energy released when an electron is added to a neutral atom ● Electronegativity: ability to attract electrons towards itself and to attract shared electrons to itself