Unit 6: Periodic Table and Bonding - Mark Rosengarten

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2) Covalent (molecular) crystal lattice, melting to form freely-moving molecules. Notice in the SOLID MOLECULAR CRYSTAL, the molecules are locked in place, unable to move around. When the ions are broken up by adding heat or dissolving in water, the molecules are now free. If you place wires connected to a source of electricity (like a battery) into the water, there are no charged ions to carry the electrical charge from one wire to the other wire, so electric current cannot flow. Molecular substances are not made of charged particles, so, unlike ionic compounds, they cannot conduct electricity in any phase. The exception to this are ACIDS, which contain Hydrogen bonded to other nonmetals. The bond is so polar that water molecules can break up the acid molecule into ions, because acids have the highest ionic character of any molecules. Examples of acids include hydrochloric acid (HCl), sulfuric acid (H 2 SO 4 ) and nitric acid (HNO 3 ). More about acids later in the course. Except for acids, a covalent bond CAN NOT be broken by dissolving in water. © 2011, Mark Rosengarten AE 14
SUMMING IT ALL UP Bond Bonded END Substance How the bond forms Type Elements is called Ionic M – NM 1.7 + Ionic • Metal atom (low EN) loses e - to nonmetal atom (high EN) • Metal is OXIDIZED, nonmetal is REDUCED • Metal atom forms + ion, nonmetal atom forms – ion • Oppositely charged ions attract • The attraction between the ions is the ionic bond Covalent NM – NM 0 – 1.7 Molecular NONPOLAR COVALENT • Two nonmetal atoms with an END of 0 – 0.4 share their unpaired valence electrons EVENLY • No oppositely charged ends More facts about bonding: POLAR COVALENT • Two nonmetal atoms with an END of 0.5 or higher share their unpaired valence electrons UNEVENLY • The atom with the lower electronegativity develops a slightly positive charge (δ+) • The atom with the higher electronegativity develops a slightly negative charge (δ-) Ionic • Forms ionic crystal lattices with very high melting and boiling points • Electricity is conducted by charged particles. • The ionic bond breaks when the compound is melted or dissolved in water • Breaking the bonds forms ions that are capable, like all liquid particles, of flow • Ionic liquids and solutions are good conductors of electricity • Ionic solids cannot conduct electricity, since the ions are locked in a crystal lattice and are not free to move around Covalent • Molecules are particles made up of covalently bonded nonmetal atoms • Since no ions are formed, molecular substances will never conduct electricity (exception to follow much later in the course) • Molecules can have partially charged ends, like a magnet, thanks to polar covalent bonds. Since these partially charged ends have much less charge than ions do, molecular substances have low melting and boiling points • The attraction of the δ + end of one molecule for the δ - end of another is called an intermolecular attractive force • This attractive force is what causes water to have surface tensionso insects can walk across it and so it can form a meniscus when a cup of water is slightly overfilled • Atomic orbitals in each bonded atom combine in such a way that the shared electrons belong to both of the bonded atoms and form molecular orbitals. © 2011, Mark Rosengarten AE 15
Page 1 and 2: Periodic Table and Bonding Word Alk
Page 3 and 4: 1) The Periodic Table (HW: p. 15-21
Page 5 and 6: E) Chemistry Of Metals, Nonmetals a
Page 7 and 8: Negative ions are named after the e
Page 9 and 10: 2) Bonding (HW: p. 22-24) Essential
Page 11 and 12: Example Ionic Bonding Dot Diagrams:
Page 13: How Atoms Covalently Bond To Form M
Page 17 and 18: ____4) Explain why the radius of Br
Page 19 and 20: 3) Complete the following Venn diag
Page 21 and 22: I) Chemistry of the Groups of the P
Page 23 and 24: B) Covalent Bonding _____1) Which o

Unit 6: Periodic Table and Bonding - Mark Rosengarten

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