1.2 chemical bonding_1 ppt

1.2 chemical - Introductory University Chemistry I Unit 2 Chemical Bonding Models of Chemical bonding Nomenclature& formula • You are expected

Info iconThis preview shows pages 1–16. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Introductory University Chemistry I Unit 2 Chemical Bonding Models of Chemical bonding Nomenclature & formula • You are expected to know the nomenclature and formulas of compounds • Separate lecture notes on “Names and rmulas of compounds” and related formulas of compounds” and related homework are uploaded • You are responsible to this topic as this will be included in your next midterm and the final Why do atoms form bonds? The driving force for bond formation: It lowers the potential energy for both atoms Lewis Theory • Chemical bonding involves the valence electrons of an atom . For example: Nitrogen N 1s 2 2s 2 2p 3 Valence electrons Phosphorus P 1s 2 2s 2 2p 6 3s 2 3p 3 They form similar type of bonds with other elements. They have similar chemical properties . Lewis Theory • When atoms form bonds, they acquire a filled outer shell of eight (or two for hydrogen) electrons . ( Octet Rule ) * Most elements at Period 2 obey the Octet Rule. Many other elements also obey but there are exceptions . Lewis Theory • In order to achieve an octet electron configuration, atoms may: 1 Transfer (lose, gain) electrons – Ionic bond. 2 Share electrons – Covalent bond Lewis Electron-Dot Symbols and Lewis Structures Group 1A • Na Group 2A • Mg • Number of valence • electrons Group 3A • Al • • Group 4A • Si • • Lewis Electron-Dot Symbols and Lewis Structures Ionic bond formation Li + F + F Li-Draw the Lewis Structure for the formation of Na 2 O Na O Na Na + Na + O 2-+ Ionic bond formation • Ionic bond is usually formed between metal and non-metal • The strong electrostatic force between the ions A and B forms the ionic bond Ionic bond formation • No single ionic pair exists in solid state. • It forms a giant 3-dimensional crystal lattice • Properties of ionic compounds: – High melting and boiling point solids (NaCl, m.p. = 801 o C) – Their liquid or aqueous solution conducts electricity. Ionic bond - Lattice energy Na + Cl-charge A x charge B Electrostatic energy α (Lattice energy) distance Coulomb’s Law Interionic distance = cation radius + anion radius The lattice energy charge A x charge B Electrostatic energy α distance cation charge x anion charge Lattice energy α cation radius + anion radius Which of the following pair of ionic compounds do you expect to have higher lattice energy (higher melting point)? NaCl or NaI Na + Na + Cl-I-NaCl : 801 o C NaI: 661 o C NaCl or MgO MgO or BaO Na + Cl-Mg 2+ O 2-NaCl : 801 o C MgO: 2,852 o C MgO: 2,852 o C BaO : 1,923 o C Covalent bond formation Atoms can achieve an octet structure by sharing their electrons Cl Cl + Cl Cl H H + H H Covalent bond is formed between two non-metal atoms Potential energy plot for two hydrogen atoms H (g) + H (g) H 2 (g) Strong repulsion between nuclei increases the Atoms too far to attract each other Internuclear distance (r) Energy Covalent bond formation Bond energy Inter-nuclear distance (bond length) potential energy Nuclei attract electron of the other atom For H 2 Bond energy = 432 kJ / mol Bond length = 74 pm Lewis structure for covalent...
View Full Document

This note was uploaded on 03/24/2011 for the course CHEM 103 taught by Professor Q during the Spring '11 term at American University of Antigua.

Page1 / 66

1.2 chemical - Introductory University Chemistry I Unit 2 Chemical Bonding Models of Chemical bonding Nomenclature& formula • You are expected

This preview shows document pages 1 - 16. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online