2nd Quarter Lesson 1: Quantum Numbers and Electronic Configuration PDF

2nd Quarter Lesson 1: Quantum Mechanical Description and the Electronic Structure of Atoms Section1: The Quantum Mechanical Model of the Atom Objectives 1. Describe the quantum mechanical model of the atom 2. Use quantum numbers to describe electrons in atoms 3. Explain how electrons are...

2nd Quarter Lesson 1: Quantum Mechanical Description and the Electronic Structure of Atoms Section1: The Quantum Mechanical Model of the Atom Objectives 1. Describe the quantum mechanical model of the atom 2. Use quantum numbers to describe electrons in atoms 3. Explain how electrons are arranged within the atom Recall Describe the following model of atomic structure 1. Thomson's plum pudding model 2. Rutherford’s nuclear model Lets Play Mystery Word Instruction: Answer the following questions and combine the answers to reveal the mystery word. 1 2 3 L P T H 4 L E 5 N 1. The symbol of the element in the third period with 5 valence electrons and is used in the manufacture of safety matches. 2. The symbol of the element in the first period with 2 valence electrons and used to inflate party balloons. 3. The symbols of the two gaseous elements in the second period with valence electrons equal to 5 and 6, respectively. 4. The first letter of the name of the principle which states that electrons fill atomic orbitals of the lowest available energy levels first before occupying higher levels in the atom’s ground state. 5. The symbol of the halogen with a complete electron configuration:1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p5. Hint: The “word” is often used as an indicator in acid–base titrations. It turns colourless in acidic solutions and pink in basic solutions.  Quantum Mechanical Model 1920’s Werner Heisenberg (Uncertainty Principle) Niels Bohr (Planetary model of the atom) Louis de Broglie (electron has wave properties) Erwin Schrodinger (mathematical equations using probability, quantum numbers) Heisenberg uncertainty principle it is impossible to determine simultaneously both the position and velocity of an electron or any other particle with any great degree of accuracy or certainty.  Bohr’s Planetary Model  Bohr’s model of the hydrogen atom suggests that the electron orbits the nucleus like our solar system (e.g. the planets around the sun). However, the quantum mechanical description of the hydrogen atom has proven that the Bohr’s model of electrons is incorrect. It states that we don’t know exactly where the electron is, but with high probability, we can conclude that the electron is most likely to be found in an orbital. In this lesson, you should be able to describe the electrons (e- ) in orbitals using the four quantum numbers.  Erwin Schrodinger Formulated equation that describes behavior and energies of subatomic particles. Incorporates both particle and wave behavior in terms of wave function: is proportional to the probability of finding an electron. Leads to Quantum Mechanics: we cannot pinpoint an electron in an atom but we can define the region where electrons can be in a particular time……… called a Probability map….a 3- dimensional area in space called an ORBITAL How can you describe the quantum mechanical model?  Quantum numbers 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) 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. Each main energy level has sub- levels n 1 2 3 4 Energy Sublevels s p d f g The principle quantum number, n, determines the number of sublevels within the principle energy level. 2nd Orbital Quantum Number, ℓ (Angular Momentum Quantum Number)  Indicates shape of orbital sublevels (s,p,d,f)  ℓ can be any integer from 0 to n-1  Describe the shape of the orbital  ℓ = n-1 ℓ sublevel 0 s 1 p 2 d 3 f 4 g  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  What is an orbital?  An orbital is an allowed energy state of an electron in the quantum-mechanical model of the atom; the term orbital is also used to describe the spatial distribution of the electron.  The space where there is a high probability that it is occupied by a pair of electrons.  Orbitals are solutions of Schrodinger’s equations.  Defined by the values of 4 quantum numbers: n, l, and ml , ms Orbitals Orbitals  Orbitals in Sublevels Sublevel # Orbitals # electrons s 1 2 p 3 6 d 5 10 f 7 14 g 9 18 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 Activity 1: Let’s Test Your Understanding! Directions: Answer as directed n value/s ℓ value/s Ml value/s 1. List the values of n, ℓ, and ml for orbitals in the 4d subshell. 2. What is the total number of orbitals associated with the principal quantum number n=3? Defend your answer. 3. Can an e- be described by the following set of quantum numbers? If not, indicate which of the quantum numbers has a value that is not valid: n=2, ℓ =1, m l= -1, ms= +1/2 4. Can an e- be described by the following set of quantum numbers? If not, indicate which of the quantum numbers has a value that is not valid: n=3, ℓ =1, ml=-3, ms= - 1/2 5. Can an e- be described by the following set of quantum numbers? If not, indicate which of the quantum numbers has a value that is not valid: n=1, ℓ =1, ml= +1, ms= - 1/2 Activity 2: I am ELECTRON MAN! Direction: Imagine yourself as an electron. As an electron, you should keep track of your location and activity for three days. If quantum numbers give information about the location of an electron or set of electrons, you could describe your location in any number of ways (e.g. GPS coordinates, qualitatively describing your surroundings, Google map, etc.). Since you are staying inside your home, you should specify the exact room or place you are in. Fill out the table on the next slide with the needed details and answer the questions that follow. The first row serves as an example.  Electron Name: Special Skill: Day Time Location Activity Example 1 8:00 am Dining Area, Lantican Compound 4th St. Mary Mount Village Having breakfast with family Anos, Los Baños, Laguna 1 8:00 am 1 3:00 pm 1 7:00 pm 2 8:00 am 2 2:00 pm 2 7:00 pm 3 8:00 am 3 2:00 pm 3 7:00 pm Follow-up Questions: 1. What is the importance of understanding the role of quantum numbers in chemistry? ________________________________________________ _____________________________ 2. How are GPS (Global Positioning System) and quantum numbers related to each other? ________________________________________________ _____________________________ 3. Why is it important to be aware of your location and surroundings? ________________________________________________ _____________________________ Activity 3: How Much Have You Learned? Directions: In your own words, describe the following terms in 2-3 sentences only. 1. Quantum Number _____________________________________________ __________________________________ 2. Principal Quantum Number _____________________________________________ ___________________________________ 3. Angular Quantum Number _____________________________________________ ___________________________________ 4. Magnetic Quantum Number _____________________________________________ ___________________________________ ePORTFOLIO Make an illustration of the s orbital, separated and combined p orbitals and d orbitals Reflection: You will write a personal insight using the prompts below: I understand that ________________________________ I realize that ________________________________ Section 2: Electron Configuration Mapping the electrons  Electronic Configuration Electron configuration is the arrangement of electrons within the orbitals of an atom to know more about an atom’s electronic property. The ground-state electron configuration is the most stable arrangement of electrons of an atom. All the electrons in an atom reside in the lowest energy orbitals possible in this arrangement. Since each orbital can accommodate a maximum of two electrons, using the periodic table, we can predict the electron configuration of all elements. Valence electrons are the outermost electrons of an atom. They are the highest energy electrons in an atom and are the most reactive. Valence electrons can be gained, lost, or shared to form chemical bonds unlike the inner electrons which do not participate in reactions. The number of valence electrons of each element is equal to its group number on the Periodic Table. Elements with the same number of valence electrons tend to have similar chemical properties. Three rules are used to build the electron configuration: Aufbau principle Pauli Exclusion Principle Hund’s Rule Aufbau Principle Electrons occupy orbitals of lower energy first. Orbital Diagram Filling Order diagram  -Pauli Exclusion Principle (Wolfgang Pauli, Austria, 1900-1958) -Electron Spin Quantum Number  An orbital can hold only two electrons and they must have opposite spin.  Electron Spin Quantum Number (ms): +1/2, -1/2  Hund’s Rule In a set of orbitals, the electrons will fill the orbitals in a way that would give the maximum number of parallel spins (maximum number of unpaired electrons). Analogy: Students could fill each seat of a school bus, one person at a time, before doubling up. Orbital Diagram for Hydrogen Orbital Diagram for Helium Orbital Diagram for Lithium Orbital Diagram for Beryllium Orbital Diagram for Boron Orbital Diagram for Carbon Orbital Diagram for Nitrogen Diamagnetism and Paramagnetism The behavior of an atom in relation to magnetic fields is influenced by its electron configuration. This behavior is also called as the magnetic property of an atom and is dependent on the number of electrons an atom has that are spin paired. An atom with electrons that will be very slightly affected by magnetic fields is called diamagnetic. The orbitals of this atom are all filled and therefore all its electrons are paired with an electron of opposite spin. Neon is an example of a diamagnetic atom. Conversely, atoms that do not have all their electrons spin-paired and are affected by magnetic fields are called paramagnetic. Lithium and sodium are examples of paramagnetic atoms. Empty PARAMAGNETIC Half-Filled are attracted to a magnetic field Filled MAGNETIC Activity 1: Electron Configuration and Orbital Diagrams Directions: Write the complete electron configuration of the following elements and draw their orbital diagrams. State whether the element is paramagnetic or diamagnetic. The first one is done for you. Element Number of Electron Electron Orbital Diagram Magnetic Properties Configuration Lithium 3 1s22s1 __ __ __ __ __ Paramagnetic 1s 2s 2p Oxygen Fluorine Bromine Silicon Zinc Notations of Electron Configurations Standard Shorthand Orbital box or orbital diagram Standard Notation Number of electrons of Fluorine in the sub level 2,2,5 1s 2s 2p 2 2 5 r g y n e i n E Ma el Le v e r s m b Sublevels Nu , 2 1, 2 Shorthand Notation Use the last noble gas that is located in the periodic table right before the element. Write the symbol of the noble gas in brackets. Write the remaining configuration after the brackets. Ex: Fluorine: [He] 2s2 2p5 Orbital Diagram for Fluorine Blocks in the Periodic Table Activity 2: Boarding House Analogy Directions: Imagine you are the landlord of a very strange boarding house. Your job is to fill the rooms in the building in the most efficient way possible. The rules you have to follow are as strange as the building because quantum mechanics is not like anything you might have expected. State what electron rule is being applied in the situations stated in the left side of the table. Explain each rule. Boarding House Rules Electron Rules From the Bottom Up: Rooms must be filled from the ground floor up. Fill the one room on the first floor before starting to put new tenants on the second floor. Then fill the s room before the p rooms. At higher floors the order might change a bit. Singles First: the owner of the building wants to have the tenants spread out as much as possible. For that reason singles are placed in rooms before couples. If couples must be placed into a room then all of the other rooms on that floor must already have a single in them. Opposite Gender Only: When two people are placed in a room they must be of opposite genders. No men may room together and no women may room together. This is an arbitrary rule on the part of the owners: in a just world we wouldn’t have to follow it. But quantum mechanics has nothing to do with justice. Chapter Assessment (eclassroom) EPORTFOLIO What are you eating? Directions: Research about the ingredients of your favorite food. Identify at least two elements present in the food and research about the properties and uses of each element. Fill out the table with the needed details and answer the reflection FOOD NAME: Element Properties Uses Electronic Orbital box Paramagnetic/ configuration Diagram Diamagnetic Standard notation/Short hand notation 1. 2. 3. 1. 2. 3. Quiz Write the electronic configuration in standard notation, short hand notation and orbital box notation, identify the number of the spdf orbital and write if it is paramagnetic or diamagnetic, paired and unpaired e- 1. Phosphorous 2. Chromium 3. Iron 3+ 4. Selenium - 5. Calcium Thank You!