Quantum Mechanical Model of an Atom PDF

Quantum Mechanical Model of an Atom  Objectives Describe the quantum model of an atom Describe the behavior of electron using the quantum numbers and electron configuration  RECALL What are the principle subatomic model? How do they compare in terms of cha...

Quantum Mechanical Model of an Atom  Objectives Describe the quantum model of an atom Describe the behavior of electron using the quantum numbers and electron configuration  RECALL What are the principle subatomic model? How do they compare in terms of charge and relative mass? Which subatomic particle or particles a. identify the atom b. contribute most of the atomic mass and mass number? c. are always equal in number in neutral atom? How are these subatomic particles arranged in the atom? Quantum Mechanical Model of an Atom  Atom building blocks of matter composed of proton, electron and neutron  Atomic Structure Atoms have a nucleus that contains Protons and Neutrons An atom is made of mostly empty space  Atomic Structure Electrons are contained in shells that surround the nucleus. has the least mass negative charge Protons have a positive charge Neutrons are Neutral Model of an Atom  The Bohr Model Niels Bohr proposed a planetary model of an atom. Model contains a central nucleus surrounded by electron shells  The Bohr Model model exhibits that electrons were supposed to move in orbits around the nucleus, but they could only orbit only in certain specified energy levels  Schrodinger Model proving that electrons really do display wavelike properties assumes that the electron is a wave and tries to describe the regions in space, or orbitals, where electrons are most likely to be found.  Schrodinger Model model presents that electrons are not having exact paths around the nucleus in orbits, and they cannot be located precisely within an atom proposed by Erwin Schrödinger  The Four Quantum Numbers that Describe Electrons  ORBITALS are the regions of space within an atom where the probability of finding an electron is greatest cloud-like region, ‘thick’ where electron is most likely to be found, and “then” where it will less likely be. Principal Quantum Numbers (n) are used to describe an electron in an orbit, the region in space with the greatest probability of finding the electron in an atom  Principal Quantum Number (n) determine by its average distance from the nucleus also describe the number of the electron shell n = 1,2,3,4,etc.  Principal Quantum Number (n) PRINCIPAL ELEMENT ATOMIC ELECTRON CONFIGURATION QUANTUM NUMBER NUMBER (n) Hydroge 1 1 n Lithium 3 2 Sodiu 11 3 m  Principal Quantum Number (n) 1. If an atom has 17 electrons, what is the principal quantum number of the electron in the outermost energy level? 2. If an atom has 8 electrons, what is the principal quantum number of the electron in the outermost energy level? Electron Number of Shell Electrons 1 2 2 8 3 18 4 32 5  Valence Electrons The electrons in the outer most electron shell are called valence electrons The shell containing electrons that is furthest from the nucleus is called the valence shell  Valence Electrons Each electron shell can hold a certain number of electrons Electron shells are filled from the inside out Noble Gases have full outer electron shells All other elements have partially filled outer electron shells  Azimuthal Quantum Number (l) describe the shape of the orbital designates the sublevel which the electron said to be occupy Shape of Orbitals  Atomic Orbital S Orbital (sharp) – spherical cloud that become less dense as the distance from the nucleus increases  Atomic Orbital P Orbital (Principal) – dumbbell shaped cloud having two lobes on opposite side  Atomic Orbital D Orbital (Diffused) – four leaf clover shaped cloud as an hour and as a ring  Atomic Orbital F Orbital (fundamental) – difficult to represent and too complex s=2 p=6 d = 10 f = 14  Electron Spin Quantum Number (ms) refers to the spin of an electron to the given orbital +1/2 or -1/2  Magnetic Quantum Number (ml) describe the orientation of the orbital the value of m depends on the last value of electron Electron Configuration s=2 p=6 d = 10 f = 14  Aufbau Principle Electron fill first the orbital of the lowest energy until any added electron  Pauli’s Exclusion Principle No more than two electron in an atom can occupy an orbital  Pauli’s Exclusion Principle No more than two electron in an atom can occupy an orbital  Pauli’s Exclusion Principle No more than two electron in an atom can occupy an orbital  Hund’s Rule One electron must enter first in each orbital, then second electron will be added GALIUM Activity #1 ELEMENT ELECTRON ATOMIC OBITALS Principal # CONFIGURATION Quantum (longhand method) Number (n) Br Al Rb V Mg Cd Pd