Electrons & Periodicity Lecture Notes October 7, 2024 PDF

Electrons & Periodicity October 7, 2024  The Brass Tacks Quiz #5 next session ○ Quantum Numbers {n, l, ml, ms} ○ Orbital Diagrams “The boxes…” ○ Electron Configuration 1s2 2s2 2p6 3s2 3p6…  The Brass Tacks LT #2 tentatively on Oct. 17 & 18 ○ Atomic History &...

Electrons & Periodicity October 7, 2024  The Brass Tacks Quiz #5 next session ○ Quantum Numbers {n, l, ml, ms} ○ Orbital Diagrams “The boxes…” ○ Electron Configuration 1s2 2s2 2p6 3s2 3p6…  The Brass Tacks LT #2 tentatively on Oct. 17 & 18 ○ Atomic History & Models ○ Sub. Particles & Nuc. Notation ○ Isotopes & Calculations ○ Quantum Model of the Atom ○ True Colors Lab Experiment ○ Electron Representations (QN, OD, EC) ○ Periodic Trends Materials Science Monday Materials Science Monday Chitosan Materials Science Monday β-Linked Glucosamines  Materials Science Monday Chitosan Pros: Renewable Biodegradable Biocompatible Antimicrobial  Materials Science Monday Chitosan Cons: Soft/Low Strength Insoluble High Production Costs Variability  Materials Science Monday Bioprints Due to its polymer-like nature, chitosan can be used to create bioplastics and can be used to print organs and tissues  Materials Science Monday Flocculant In the right conditions, it can bond with impurities in water, making the water more potable through sedimentation  Materials Science Monday Medical Due to its biocompatibility and antimicrobial properties, chitosan is sometimes used in the medical field  Objectives explain the periodic recurrence of similar properties among elements in terms of electronic structure relate an element’s number of valence electrons to their group number compare the properties of families of elements  Objectives predict and compare the properties of individual elements based on their position in the periodic table describe and explain the trends in atomic properties in the periodic table Materials Science Monday  The Periodic Table of Elements  Trending on the Table The Law of Triads (1829) Johann Wolfgang Dobereiner proposed the arithmetic mean in a triad could calculate for properties of elements in between  Trending on the Table The Law of Triads (1829)  Trending on the Table Dumas Method (1858-1860) Jean-Baptiste Dumas refined the determination of the atomic mass using the element’s vapor density, allowing for more accurate atomic masses  Trending on the Table Dumas Method (1858-1860) dRT M = P  Trending on the Table The Law of Octaves (1865) John Newlands proposed that every eighth element has similar properties when organized on the periodic table  Trending on the Table The Law of Octaves (1865)  Dmitri Mendeleev The original periodic table was developed by a Russian chemist named Dmitri Mendeleev  Dmitri Mendeleev During the mid-1800’s there were about seventy known elements, which Mendeleev arranged in order of increasing atomic mass Listing the elements in this order caused certain sets of properties to reoccur in a periodic pattern  Mendeleev’s Table Mendeleev’s table left gaps for undiscovered elements, which allowed him to predict the existence and properties of unknown elements Henry Moseley Henry Moseley was an English physicist responsible for the creation of the modern periodic table Parts of a Periodic Table Period Group Horizontal rows Vertical columns on on the periodic the periodic table table numbered: numbered: 1-7 1 - 18  1 - 18 Not counted Parts of a Periodic Table Period Group Horizontal rows Vertical columns on on the periodic the periodic table table numbered: numbered: 1-7 I - VIII; A or B IA - VIIIA Not counted  IB IIB IIIB - VIIIB VIIIB Parts of a Periodic Table Period Group Elements in the Elements in the same period same group have variable have similar chemical chemical properties properties  Parts of a Periodic Table Period Group The first element is All elements in the always an active same group have solid, the last is an the same number of inactive gas valence electrons  Let’s Examine! Determine the Noble Gas Electron Configuration: 2 2 C [He] 2s 2p 2 2 Si [Ne] 3s 3p 2 10 2 Ge [Ar] 4s 3d 4p Sn 2 [Kr] 5s 4d 5p 10 2  Let’s Examine! How many electrons are in the highest energy level? 2 2 - C [He] 2s 2p 4e 2 2 - Si [Ne] 3s 3p 4e 2 10 2 - Ge [Ar] 4s 3d 4p 4e Sn 2 [Kr] 5s 4d 5p 10 2 4e -  Valence Electrons? Electrons that are transferred or shared when atoms bond together ○ Transferred - Ionic Bonds ○ Shared - Covalent Bonds Generally the electrons in the outer energy level of an atom (recall our electron configuration of our ions)  IUPAC Group Names The International Union of Pure and Applied Chemistry (IUPAC) provides trivial names to several groups (specifically the IA-VIIIA) on the Periodic Table Kindly familiarize yourself with these as these may be used interchangeably (For now, ignore the values, they represent Electron Affinity)  IUPAC Group Names Grp. Name 1A Alkali Metals (form alkali solutions) 2A Alkaline Earth Metals (oxides ≈ earth) 3A Triels (Tri = 3) 4A Tetrels (Tetra = 4)  IUPAC Group Names Grp. Name 5A Pnictogens (“to choke”) 6A Chalcogens (“ore-forming”) 7A Halogens (“salt-forming”) 8A Noble Gases (“low reactivity”) Periodic Trends Trends in Periodic Properties The physical and chemical behavior of the elements is based on the electron configurations of their atoms Electron configurations can be used to explain many of the repeating properties of elements Trends in Periodic Properties The Periodic Law The properties of elements are periodic functions of their atomic numbers Recall, the proton is responsible for the identity of the atom Trends in Periodic Properties In general, changes in periodic properties are more drastic by periods than groups ○ Compare within periods before comparing the periods ○ Ensure there is a standard of comparison between atoms  Atomic Radius What increases gradually Principal going down groups? Quantum Number What increases gradually going across periods? Atomic Number  Atomic Radius The size of elements follow two rules: Increases going down a group ○ Higher n Quantum Number = Bigger Decreases going left to right a period ○ Electron shielding; more protons, more attractive forces between nucleus  Let’s Practice! Order the following elements in terms of decreasing atomic size [Ca, Mg, Sr] [Br, Rb, Kr] [K, Ga, Ca] [Sr, Ca, Rb]  Let’s Practice! Order the following elements in terms of decreasing atomic size [Sr > Ca > Mg] [Rb > Br > Kr] [K > Ca > Ga] [Rb > Sr > Ca]  Types of Ions Anion Cation Negatively Positively charged ions charged ions 🧅＞﹏＜ 😸  Ionic Size Ionic Sizes depend on the Ion: Cations are smaller than original atom ○ Repulsion Forces < Attractive Forces Anions are larger than original atom ○ Repulsion Forces > Attractive Forces  - e *gasp* Free space! - e Fill in the gap!  Smaller electron shell - e- e-  - e Can I come in? 🥺 - e 😐 e- e- Bigger electron shell e-  Ionic Size In an isoelectronic series: ○ Most negative ions are largest ○ Most positive ions are smallest Atoms making more than one ion, most negative is the largest  Let’s Practice! Order the following ions in terms of decreasing atomic size [Ca2+, Mg2+, Sr2+] + 2- - [K , S , Cl ] [Au+, Au3+] Electrons & Periodicity October 7, 2024  THANKS! Do you have any questions? 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