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ATOMIC STRUCTURE:A FOUNDATION FOR MATERIALS ENGR. JOHN CHRISTIAN S. BONDAUG, MSc. DECODING THE ATOM The fundamental of material science IMPORTANCE The role of atomic structure in chemical reactions and energy technologies drives innovation across various scientific disciplines. The atom's structure shapes the behavior of matter, underpinning current chemistry, physics, and technology. Understanding atomic structure unlocks perspectives on material properties, propelling scientific advancements. WHAT IS AN ATOM? The atom is the fund amental unit of matter. It consists of a central nucleus containing positively charged neutrons, surrounded protons and neutral by a cloud of negatively charged electrons. The interaction between these particles determines the properties and behavior of materials. ATOMIC IDENTITY OF AN ELEMENT 1. ATOMIC NUMBER The number of protons in the nucleus i 9 6. y 6 re) 5 re) y 7 9 | txe]arsd%s 2. MASS NUMBER Number of protons and neutrons Melting point: 1064.18°C Boiling point: 2970°C 3. ELECTRON CONFIGURATION G O L 'D) The arrangement of electrons orbiting the nucleus is Latin name: Aurum referred to as electronic configuration. WHAT IS ELECTRON CONFIGURATION? The arrangement of electrons orbiting the nucleus is referred to as electronic configuration. ——L IE: The electronic configuration dictates how an atom interacts with others, influencing its ability to form chemical bonds and engage in reactions. This understanding is crucial for explaining the properties and behaviors of elements in the periodic table. ELECTRONIC CONFIGURATION electrons per level 32e) GB) orbitalname = (K) «=(L) (M) (N) (0) (P) (Q) eeorguthews (+) (an) (and) (ant) (ana) (an ELEMENTS REACTIVITY K shell ©) _ @ _ ne whose outer shells rlemaunUhnou whose outer shells are not filled are chemically are filled are chemically inert reactive o— PROPERTIES OF ELEMENTS 1, ELECTRONEGATIVITY It describes the tendency of an atom or a functional group to attract electrons toward itself e. ELECTROPOSITIVITY Its the tendency of an atom to donate electrons and form positively charged cations A measure of the attraction between the incoming electron and the nucleus - the stronger the attraction, the more energy is released 3. IONIZATION ENERGY The amount of energy required to remove an electron from an isolated atom or molecule. 3. ELECTRON AFFINITY | \ PROPERTIES OF ELEMENTS Ionization Energy Electron Affinity Ionization Energy Electron Affinity IONIC BONDING Type of linkage formed from the electrostatic attraction between oppositely charged ions in a chemical compound The elements in the compound are metal and non-metal, then the bonding will be ionic COVALENT BONDING The interatomic linkage that results from the sharing of an electron pair between two atoms to form stable molecule. “Electrons are at the same time pulled in by more than one core" SECONDARY BONDING/INTERMOLECULAR FORCES Ion-ion interactions are an attractive force between ions with opposite charges Intermolecular Forces Intermolecular forces are attractive and repulsive forces Hydrogen bonding, interaction involving a between separate molecules. hydrogen atom located between a pair of = . . oe — Z other atoms having a high affinity for H-E- tLe -o ‘o electrons Hydrogen Bond re Dipole - Dipole ; ; . ; Ey Dipole-dipole interactions are weak O O interactions that arise from the close Nate=Cl H__!on- Dipole association of permanent or induced ae ro Na* dipoles f & 5+ The London dispersion force is a temporary H sciencenotes.org attractive force that results when the electrons in two adjacent atoms occupy positions that make the atoms form temporary dipoles; weakest. SECONDARY BONDING/INTERMOLECULAR FORCES Functional Groups force ingases Force Nature of Attraction Example Relative Strength Commonly Involved Attraction between Charged molecules, ions lon-ion positively-charged and Nat*-Cl Very stron (AKA ionic) negatively-chargedion y g (Table salt!) Interaction with a charged H A molecule with a strong : ion anda molecule witha Nat J dipole (e.g. H,O) interacting lon-dipole dipole Gowan nnn iN Strong with an ion (Nat, Cat, K+, Br, H Ch...) A strong type of dipole- H Alcohols (CH;OH) dipole interactionbetween WA Carboxylic acids (COOH) anacidichydrogenanda H------! ON Arines (NH) Hydrogen bond Jone pair A H Medium H (Water molecules!) Two molecules with strong Compounds that contain a Dipole-dipole dipoles are attracted to H—cl------- H—cl Weak polarbond each other All compounds have these Alkanes (CH;) Dis - Attraction of weak dipoles b- b+ 6-. b+ Alkenes (CH {CH,) persion : that form at any giventime F—F------- F—F Benzene (AKA London NM Se Very weak . when molecules are close Molecules with zero net Forces) The primary intermolecular dipole (I>, Fs...) Increasing Boiling Point 
