Quantum Atomic Models PDF

History, Models, and Structures of the Atom Electrons In Atoms 5.1 Revising the Atomic Model 5.2 Electron Arrangement in Atoms 5.3 Atomic Emission Spectra and the Quantum Mechanical Model Democritus Believed universe made of invisible units called atoms Named them Atoms 400 BC...

History, Models, and Structures of the Atom Electrons In Atoms 5.1 Revising the Atomic Model 5.2 Electron Arrangement in Atoms 5.3 Atomic Emission Spectra and the Quantum Mechanical Model Democritus Believed universe made of invisible units called atoms Named them Atoms 400 BC Aristotle said “He’s a quack!!!” Took 2000 yrs to be proved right!  Dalton’s Atomic Theory John Dalton (1766 – 1844) Wrote the first atomic theory 1. All elements are composed of tiny indivisible particles called atoms 2. Atoms of the same element are identical. Atoms of any one element are different from those of any other element. 3. Atoms of different elements combine in simple whole-number ratios to form chemical compounds 4. In chemical reactions, atoms are combined, separated, or rearranged – but never changed into atoms of another element. The “Billiard Ball” Model proposed by John Dalton in 1804 this theory proposed that matter was composed of small, spherical particles but evidence was later gathered that matter was composed of even smaller bits Thomson: “Plum Pudding” or “Chocolate Chip Cookie” Model using available data on the atom, J.J. Thomson came up with the idea of having charges embedded with Dalton’s Billiard Balls Also used cathode ray experiment to discover the existance of the electron positive negative (evenly distributed) “chocolate” “dough” part note: this model kept Dalton’s key ideas intact  Discovery of the Electron In 1897, J.J. Thomson used a cathode ray tube to deduce the presence of a negatively charged particle: the electron Click on me: http://www.mhhe.com/physsci/chemistry/essentialchemistry/flash/ruther14.swf Nuclear Model Ernest Rutherford discovered a huge flaw in the previous concept of the atom during his now famous gold foil experiment Rutherford Discovered the Nucleus and the Positive Protons Surmised atoms are made of mostly empty space Didn’t know about the Neutrons Famous Gold Foil Experiment Click on me: http://www.mhhe.com/physsci/chemistry/essentialchemistry/flash/r uther14.swf Gold Foil Experiment Particles shot through thin sheet of gold Most shots went straight through A small amount were deflected Hence… The atoms must be made of mostly empty space with a small dense nucleus  Rutherford’s Findings * Most of the particles passed right through * A few particles were deflected * VERY FEW were greatly deflected “Like howitzer shells bouncing off of tissue paper!” Conclusions: #1 The nucleus is small #2 The nucleus is dense #3 The nucleus is positively charged Niels Bohr Discovered that electrons exist in several distinct layers or levels “Jimmy Neutron Model” Travel around nucleus like planets travel around sun Electrons Orbit Electrons can jump between levels with energy being added/released Bohr Model Niels Bohr proposed that electrons revolve around the central positive nucleus (like planets in the solar system) negative electrons 3 positive protons ELECTRON CONFIGURATION Each possible electron orbit in Bohr’s model has a fixed energy. The fixed energies an electron can have are called energy levels. A quantum of energy is the amount of energy required to move an electron from one energy level to another energy level. Bohr Model Bohr also suggested that the electrons can only revolve in certain orbits, or at certain energy levels (ie, the energy levels are quantized) no energy level in between steps Heisenberg and Schrodinger Found that Electrons live in fuzzy regions or “clouds” not distinct orbits Improved on Bohr’s findings Electron location can not be predicted Quantum Mechanical Model The Quantum Mechanical Model What does the quantum mechanical model determine about the electrons in an atom?  Austrian physicist Erwin Schrödinger (1887–1961) used new theoretical calculations and experimental results to devise and solve a mathematical equation describing the behavior of the electron in a hydrogen atom. The modern description of the electrons in atoms, the quantum mechanical model, came from the mathematical solutions to the Schrödinger equation.  Energy Levels in Atoms The Bohr Model Bohr proposed that an electron is found only in specific circular paths, or orbits, around the nucleus. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.  Energy Levels in Atoms The Bohr Model Each possible electron orbit in Bohr’s model has a fixed energy. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.  Energy Levels in Atoms The Bohr Model Each possible electron orbit in Bohr’s model has a fixed energy. The fixed energies an electron can have are called energy levels. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.  Energy Levels in Atoms The Bohr Model Each possible electron orbit in Bohr’s model has a fixed energy. The fixed energies an electron can have are called energy levels. A quantum of energy is the amount of energy required to move an electron from one energy level to another energy level. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.  Energy Levels in Atoms The Bohr Model The rungs on this ladder are somewhat like the energy levels in Bohr’s model of the atom. A person on a ladder cannot stand between the rungs. Similarly, the electrons in an atom cannot exist between energy levels. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.  Energy Levels in Atoms The Bohr Model The rungs on this ladder are somewhat like the energy levels in Bohr’s model of the atom. The energy levels in atoms are unequally spaced, like the rungs in this unusual ladder. The higher energy levels are closer together. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.  How does the Bohr model improve upon the Rutherford model? Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.  How does the Bohr model improve upon the Rutherford model? The Rutherford model could not explain why elements that have been heated to higher and higher temperatures give off different colors of light. The Bohr model explains how the energy levels of electrons in an atom change when the atom emits light. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.  The Quantum Mechanical Model The Quantum Mechanical Model What does the quantum mechanical model determine about the electrons in an atom? Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.  The Quantum Mechanical Model Austrian physicist Erwin Schrödinger (1887– 1961) used new theoretical calculations and experimental results to devise and solve a mathematical equation describing the behavior of the electron in a hydrogen atom. The modern description of the electrons in atoms, the quantum mechanical model, came from the mathematical solutions to the Schrödinger equation. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.  The Quantum Mechanical Model Like the Bohr model, the quantum mechanical model of the atom restricts the energy of electrons to certain values. Unlike the Bohr model, however, the quantum mechanical model does not specify an exact path the electron takes around the nucleus. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.  The Quantum Mechanical Model The quantum mechanical model determines the allowed energies an electron can have and how likely it is to find the electron in various locations around the nucleus of an atom. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.  Key Concepts Bohr proposed that an electron is found only in specific circular paths, or orbits, around the nucleus. The quantum mechanical model determines the allowed energies an electron can have and how likely it is to find the electron in various locations around the nucleus of an atom. Each energy sublevel corresponds to one or more orbitals of different shapes, which describe where the electron is likely to be found. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.  Glossary Terms energy level: the specific energies an electron in an atom or other system can have quantum: the amount of energy needed to move an electron from one energy level to another Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.  Glossary Terms quantum mechanical model: the modern description, primarily mathematical, of the behavior of electrons in atoms atomic orbital: a mathematical expression describing the probability of finding an electron at various locations; usually represented by the region of space around the nucleus where there is a high probability of finding an electron Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.  Quantum #’s are like an Address. What do you need to know to find out where you live? State City Street House Principle Angular Magnetic Spin Quantum Quantum Quantum Quantum number number number number (n) (ℓ) (mℓ) (ms)  1. Quantum Numbers Modern atomic theory states that any electron in an atom can be completely describe by four quantum numbers: n, l, ml ,ms 1st Quantum Number: Principal Quantum Number (n) Refers to the principal energy levels. n 1 2 3 4 2nd Quantum Number: Azimuthal or Angular Momentum Quantum Number (ℓ)  ℓ can be any integer from 0 to n-1 Sublevel (s,p,d,f) Describe the shape of the orbital Letter s p d f ℓ 0 1 2 3  letter s p d f ℓ 0 1 2 3 Example: n = 3 ℓ = 0 ….n-1 ℓ = 0 ….(3-1) ℓ = 0 to 2  S,P,D,F s: Sharp p: Principal d: Diffuse f: Fundamental The s, p, d, and f stand for "sharp," "principal," "diffuse," and "fundamental," respectively, and are so named because they categorize the spectral lines generated by those types of orbitals: Electron configuration 3rd Quantum Number: Magnetic Quantum Number (mℓ) Designates the specific three dimensional orientation of the orbital ℓ. s subshell: spherical 1S 2S 3S p subshell : dumbbell shape 3 orbitals z x y x y z d subshell mℓ can be any integer from: - ℓ to + ℓ Example: ℓ= 2 mℓ = -2, -1, 0, +1, +2  S ___ 0 p ___ ____ ____ -1 0 1 d ____ ____ ____ ____ ____ -2 -1 0 1 2 f ____ ____ ____ ____ ____ ____ ____ -3 -2 -1 0 1 2 3 Valu Su Values of Possible e of b ml orbitals she l ll 0 s 0 S 1 p -1 , 0 , 1 Px,Py,Pz 2 d -2, -1, 0, 1, 2 dxy,dxz,dyz,dx2y2, dz2 3 f -3, -2, -1, 0, 1, 2,3 4th Quantum Number: Spin Quantum Number (ms ) the spin of the electron. Electrons in the same orbital must have opposite spins. 1 1 + or - The value of ms = 2 2 +½ -½ 2S  z ° +½ -½ y x Possible spins are clockwise or counterclockwise Empty PARAMAGNETIC Half-Filled are attracted to a magnetic field Filled MAGNETIC The Pauli exclusion principle (Wolfgang Pauli, Nobel Prize 1945) states that: no two electrons in the same atom can have identical values for all four of their quantum numbers. What this means is that no more than two electrons can occupy the same orbital, and that two electrons in the same orbital must have opposite spins. Summary  Quantum Numbers n, l, ml, ms ORBITA PE L SPI L N SUBLEVE L SHAPE  l = SUBLEVEL (s,p,d,f) S=0 P=1 d=2 F=3  ml = orbital s ___ p ___ ___ 0 ___ -1 0 1 d ___ ___ ___ ___ ___ -2 -1 0 1 2 f ___ ___ ___ ___ ___ ___ ___ -3 -2 -1 0 1 2 3 ms = +1/2, -1/2 Spin!  Number of Orbital Number of n l ml orbitals Name electrons 1 0 0 1 1s 2 2 0 0 1 2s 2 1 -1, 0, +1 3 2p 6 3 0 0 1 3s 2 1 -1, 0, +1 3 3p 6 -2, -1, 0, +1, 2 5 3d 10 +2 4 0 0 1 4s 2 1 -1, 0, +1 3 4p 6 -2, -1, 0, +1, 2 5 4d 10 +2 -3, -2, -1, 0, 3 7 4f 14 +1, +2, +3 TEST YOUR UNDERSTANDING  s= 0 Oxygen P= 1 d =2 ___ ___ ___ ___ ___ 1s2 2 s2 2p4 f= 3 s ___ n l ml ms 0 1 0 0 1/2  s= 0 Oxygen P= 1 d =2 ___ ___ ___ ___ ___ 1s 2s 2p f= 3 s ___ n l ml ms 0 1 0 0 - 1/2  s= 0 Oxygen P= 1 d =2 ___ ___ ___ ___ ___ 1s 2s 2p f= 3 p ___ ___ ___ n l m ms -1 0 l 1 2 1 1 1/2 1. An atom of hydrogen has one electron and is labeled 1 s1. What will the quantum be? n= ℓ= mℓ = ms = 1st: Principal Quantum Number (n) 1 s 1 Answer: n= 1  2nd: The angular momentum quantum Number (ℓ) or subshell s= 0 P= 1s 1 1 d =2 f= 3 Answer: ℓ= 0 because ℓ is a number from 0 to n-1 3rd: Magnetic Quantum Number (ml) -l to +l 1s 1 s ___ 0 ml = 0 4th: Spin Quantum Number (ms ) 1 1s 1 + 2 Answer: + 1 2 The Quantum Numbers are: 1, 0, 0, 1 2  2. Assign quantum numbers to the valence electrons of a lithium atom 1s22s1 See your periodic table 1st: Principal Quantum Number (n) 1s 2s 2 1 Answer: n= 2  2nd: The angular momentum quantum Number (ℓ) or subshell 1s 2 2 s= 0 s 1 P= 1 d =2 Answer: ℓ= 0 f= 3 3rd: Magnetic Quantum Number (ml) -l to +l s ___ 1s 22 0 s 1 ml = 0 , because the value of l is 0  4th: Spin Quantum Number (ms ) 1 1s 2 2 + 2 s 1 Answer: +1 2 The quantum numbers are: 2,0,0, + 1/2 3. What are the four quantum numbers that represent an electron in 2 s orbital s= 0 n=2 ℓ= 0 P= 1 d =2 mℓ= ms= +½ f= 3 0 -½ 4. What are the four quantum numbers that represent an electron in 3 p orbital s= 0 n=3 ℓ= 1 P= 1 d =2 ms= +½ mℓ= -1 f= 3 -½ 5. What are the four quantum numbers that represent an electron in 5 d orbital s= 0 n=5 ℓ= 2 P= 1 d =2 mℓ= -2 -1 0 +1 +2 f= 3 ms= +½ -½ 6. What are the four quantum numbers that represent an electron in 4 f orbital s= 0 P= n=4 ℓ= 3 1 d =2 f= 3 mℓ= - 3 -2 -1 0 +1 +2 + 3 ms= +½ -½  7. Where is an electron with the quantum numbers: s= 0 n=4 mℓ = P= ℓ=2 0m = +½ 1 s d =2 f= 3 4d  8. Where is an electron with the quantum numbers: n=2 mℓ= 0 ℓ= 0 ms= -½ 2 s2  s p sharp principal d f diffuse fundamental 9. Assign quantum numbers for the tenth electron to fill a neon atom. [He] 2s2 2p6 1s2 2s2 2p6 1 2 2 s s p p p 10. Assign quantum numbers for the tenth electron to fill a neon atom. 1s2 2s2 2p6 1 2 2 s s p p p Ml = 1 ms = - 1/2 n=2 L=1 END OF THE SHOW !!!