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SCAN0023

# SCAN0023 - Chapter 1 Class Notes Structure Determines...

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Unformatted text preview: Chapter 1 Class Notes: Structure Determines Properties 1. Atoms, Electrons, and Orbitals 1.1 Nucleus (protons and neutrons) 6 Electron cloud (electrons) Atoms are composed of Protons positively charged mass = 1.6726 X 10‘27 kg 1 Neutrons neutral mass = 1.6750 X 10'27 kg Electrons negatively charged mass = 9.1096 X 10‘31 kg Atomic Number and Mass Number Atoms are symbolized in writing, as ZX , smce the Z 15 redundant due to the symbol, a symbol of AX suffices. 97‘ of protons 3: # of electrons in a neutral atom Atomic Number, Z = number of protons in a nucleus = defines the element '— The number above eac riodic table is its atomic number Mass Number, A = sum of the number of protons and neutrons. Example: a) What is the mass number of an iron atom with 30 neutrons? Iron, Fe: 26 is the atomic number, therefore it has 26 protons. Mass number = # of neutrons plus protons so 26+30 = 5 6 Schrodinger Equation Schrodinger combined the idea that an electron has wave properties with classical equations of wave motion to give a wave equation for the energy of an electron in an atom. Wave equation (S chrodinger equation) gives a series of solutions called wave functions (VI). Wave Functions 19 Only certain values of y/ are allowed. Each 1/1 corresponds to a certain energy. The probability of ﬁnding an electron at a particular point with respect to the nucleus is given by V72 Each energy state corresponds to an orbital. Quantum Numbers Each orbital is characterized by a unique set of quantum numbers. The principal quantum number n is a whole number (integer) that speciﬁes the shell and is related to the energy of the orbital. The angular momentum quantum number is usually designated by a letter (s, p, d, f, etc) and describes the shape of the orbital. s Orbitals are spherically symmetric. p Orbitals — dumbbell shape, Are not possible for n = 1. Are possible for n = 2 and higher. ...
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