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Compounds and Their Bonds

Compounds and Their Bonds. Ionic Compounds Naming Ionic Formulas. Using The Periodic Table. Valence Shell:. Full = 0. 3+. 4±. 3–. 2–. 1–. 2+. 1+. Formulas of Ionic Compounds. Formulas of ionic compounds are determined from the charges on the ions atoms ions

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Compounds and Their Bonds

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  1. Compounds and Their Bonds Ionic Compounds Naming Ionic Formulas

  2. Using The Periodic Table Valence Shell: Full = 0 3+ 4± 3– 2– 1– 2+ 1+

  3. Formulas of Ionic Compounds Formulas of ionic compounds are determined from the charges on the ions atoms ions  – Na  +  F :  Na+ : F :  NaF  sodium fluorine sodium fluoride formula Charge balance: 1+1- = 0

  4. Simple Ionic Compounds: In order to write the formula of a simple ionic compound from its name, follow these steps: • Print the symbols for each element involved. The metalis always listed first, followed by the non-metal. potassium oxide K O • Record the valences for each element above the symbol. The valence of the metal is copied directly from the periodic table. The valence of the non-metal is based on its family on the periodic table. ( Halogens like F, Cl, Br and I are always 1-; elements in the family with O are 2-; elements in the family with N are 3-) K1+ O2-

  5. Ignore the + and – signs and criss-cross the valences. The valence from the metal ends up with the non-metal and the valence from the non-metal with the metal. K2O1 • Reduce the numbers to their lowest possible ratios and eliminate any 1’s. K2O • To write the name from the formula, record the name of the metal first as listed on the periodic table and then record the non-metal changing the ending to -IDE. Mg3P2 magnesium phosphide

  6. Chemical Formula for IonicCompounds Criss-Cross Shortcut • Write the Symbols of the elements with the metal first. • Determine each element’s charge and place that number above the symbol. • Criss-cross the numbers so that they become subscripts for the opposite symbol. • Reduce the subscripts if possible.

  7. alkalis (1st column elements) form "+1" ions such as Na+ and Li+ • alkaline earth metals (2nd column elements) form "2+" ions such as Mg2+ and Ba2+ • halogens (7th column elements) form "-1" ions such as Cl- and I-

  8. Learning Check Write the correct formula for the compounds containing the following ions: A. Na+, S2- 1) NaS 2) Na2S 3) NaS2 B. Al3+, Cl- 1) AlCl3 2) AlCl 3) Al3Cl C. Mg2+, N3- 1) MgN 2) Mg2N3 3) Mg3N2

  9. Solution A. Na+, S2- 2) Na2S B. Al3+, Cl- 1) AlCl3 C. Mg2+, N3- 3) Mg3N2

  10. Naming Binary Ionic Compounds • Contain 2 different elements • Name the metal first, then the nonmetal as -ide. • Use name of a metal with a fixed charge Groups 1A, 2A, 3A and Ag, Zn, and Cd Examples: NaCl sodium chloride ZnI2 zinc iodide Al2O3 aluminum oxide

  11. Learning Check Complete the names of the following binary compounds: Na3N sodium ________________ KBr potassium ________________ Al2O3 aluminum ________________ MgS _________________________

  12. Solution Complete the names of the following binary compounds: Na3N sodium nitride KBr potassium bromide Al2O3 aluminum oxide MgS magnesium sulfide

  13. Practice

  14. Transition Metals: PolyValent Ionic Bonding If an element can form more than one (1) positive ion, the charge is indicated by the Roman numeral in parentheses followed by the word "ion" 1+ 2+ 1+ or 2+ 2+ or 3+ Ag+ Cd2+ Cu+,Cu2+ Fe2+, Fe3+ silver cadmium copper(I) ion iron(II) ion ion ion copper (II) ion iron(III) ion Zn2+ zinc ion

  15. Names of Variable Ions Use a roman number after the name of a metal that forms two or more ions Transition metals and the metals in groups 4A and 5A FeCl3(Fe3+) iron (III) chloride CuCl (Cu+ ) copper (I) chloride SnF4 (Sn4+) tin (IV) fluoride PbCl2 (Pb2+) lead (II) chloride Fe2S3 (Fe3+) iron (III) sulfide

  16. Practice

  17. Covalent Bonding

  18. Covalent Bonding: The Nice Way • In ionic bonding, electrons were taken from one atom by another creating ions which then held together due to electromagnetic forces (opposite charges) • Covalent (molecular) bonding is a process by which two atoms SHARE electrons. (Hence the name CO-VALENT)

  19. Covalent Bonding: The Nice Way • A covalent bond is when a pair of electrons is shared between two non-metal atoms to create a stable molecule and hold the atoms together • Shared electron pair • NON-metals only • Stable molecule • Holds atoms together • Electrons orbit BOTH atoms

  20. Lewis Diagrams • Lewis dot diagrams can also be used to show bonding between atoms. • The bonding electrons are placed between the atoms and can be represented by a pair of dots or a dash (each dash represents one pair of electrons, or one bond). • Lewis structures for H2 and O2 are shown below.

  21. Naming Covalent Bonds • Molecular compounds are formed from the covalent bonding between non-metallic elements. The nomenclature for these compounds is described in the following set of rules. • The more positive atom is written first (the atom which is the furthest to the left and to the bottom of the periodic table) • The more negative second atom has an "-ide" ending. • Each prefix indicates the number of each atom present in the compound. Examples:CO2 = carbon dioxideP4S10 = tetraphosphorus decasulfide

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