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Ionic Bonding Topic 4.1

Ionic Bonding Topic 4.1. http://www.youtube.com/watch?v=xTx_DWboEVs. http://www.youtube.com/watch?v=5IJqPU11ngY. “Review”. Valence electrons electrons in the highest occupied energy level always in the s and p orbitals normally just a draw a circle to represent these two orbitals

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Ionic Bonding Topic 4.1

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  1. Ionic BondingTopic 4.1 http://www.youtube.com/watch?v=xTx_DWboEVs http://www.youtube.com/watch?v=5IJqPU11ngY

  2. “Review” • Valence electrons • electrons in the highest occupied energy level • always in the s and p orbitals • normally just a draw a circle to represent these two orbitals • determines the chemical properties of an element • usually the only electrons used in chemical bonds

  3. IB may group levels together and therefore you would see the 3d10 before the 4s2 http://wps.prenhall.com/wps/media/objects/476/488316/Instructor_Resources/Chapter_09/FG09_27-06un.JPG

  4. IB uses this one

  5. Lewis/Electron Dot Diagrams/Structures • electron dot structures/diagrams are used to show valence electrons • each dot around the element symbol represents a valence electron

  6. B is 1s2 2s2 2p1; • 2is the outermost energy level • it contains 3 valence electrons, 2 in the s and 1 in the p • Br is [Ar] 4s2 3d10 4p5How many valence electrons are present?

  7. http://images.google.com/imgres?imgurl=http://hyperphysics.phy-astr.gsu.edu/hbase/pertab/imgper/econfig.gif&imgrefurl=http://hyperphysics.phy-astr.gsu.edu/hbase/pertab/perlewis.html&h=267&w=512&sz=22&tbnid=__EXctBwlG0J:&tbnh=66&tbnw=128&hl=en&start=1&prev=/images%3Fq%3DElectron%2BDot%2BDiagrams%26svnum%3D10%26hl%3Den%26lr%3Dhttp://images.google.com/imgres?imgurl=http://hyperphysics.phy-astr.gsu.edu/hbase/pertab/imgper/econfig.gif&imgrefurl=http://hyperphysics.phy-astr.gsu.edu/hbase/pertab/perlewis.html&h=267&w=512&sz=22&tbnid=__EXctBwlG0J:&tbnh=66&tbnw=128&hl=en&start=1&prev=/images%3Fq%3DElectron%2BDot%2BDiagrams%26svnum%3D10%26hl%3Den%26lr%3D

  8. Ionic Charge • when forming compounds, atoms tend to achieve the electron configuration of a noble gas (ns2np6) • this means their highest energy level will be filled with 8 electrons the easiest way possible • atoms of metallic elements (groups 1,2,3) lose electrons producing cations (positive ions) • Ca becomes Ca2+ • atoms of nonmetallic elements (groups 5,6,7) gain electrons producing anions (negative ions) • Cl becomes Cl1- • group 4 can go either way • often loose four electrons and become a 4+ cation

  9. N O F Ne Na Mg N3- Na+ Mg2+ O2- F1- Cations Anions

  10. 1+ 2+ 3+ 4+/- 3- 2- 1- 0 As it turns out, atoms bond together for a very simple reason: atoms like to have full valence shells.

  11. transitional metals can often form more than one cation and therefore charges may vary • iron can be Fe2+ or Fe3+ • may fill some orbitals but might not get a noble gas electron configuration

  12. Formation of Ionic Compounds • usually composed oppositely charged metallic cations and nonmetallic anions • because of the electrostatic attraction between oppositely charged particles • electro- electricity/electrons • static- non-moving (vs. current which is moving charges) • form a compound with overall zero charge - anions + cations

  13. ions must have a difference in electronegativity of 1.7 or greater to form an ionic bond

  14. electronegativty difference probable type of bond 0.0 covalent, nonpolar covalent, slightly polar 0.1 – 1.0 covalent, very polar 1.1– 1.7 ionic >1.7

  15. Na “gives” Cl one electron and now both atoms have a full valence shell (electron configuration of a noble gas) 3 .9

  16. e– 1) 2) Na Cl Cl– Na+ 3)

  17. Chemical Formula • shows the kinds and numbers of atoms in the lowest whole-number ratio of ions in the ionic compound • Na 1+ + Cl1- NaCl • Ca 2+ + Cl1-  CaCl2 • Mg 2+ + O 2-  MgO

  18. Mg and N? • Mg2+, N3- • it takes two nitrogens to combine with three magnesiums • Mg3N2 • magnesium nitride

  19. Na 1+ + F 1- NaF

  20. Properties of Ionic Compounds • high melting points • can conduct electric currents when melted or dissolved in water • crystalline structure • repeating arrays of cations and ions • an ionic lattice

  21. Naming Ions and Writing Ionic Compounds

  22. Naming Ions Monoatomic ions • cationslose valence electrons and therefore are positively charged • transition metals form more than one cation with different ionic charges • charge is determined from the # of electrons lost • Fe2+ lost two electrons (the 2 in the 4s) • Fe3+ lost three electrons (the 2 in the 4s and 1 in the 3d) • naming • Stock system • a Roman numeral is used to show the charge of the transition metal • Fe2+ is iron(II) and Fe+3 is iron(III)

  23. anions gain valence electrons and therefore are negatively charged • change ending to –ide for the name

  24. Polyatomic ions (look at list) • composed of more than one atom that form a single unit/ion with a charge • most end with -ite or –ate • the –ite ending indicates one less oxygen than the –ate ending • ionic charge is the same for both

  25. Naming ionic compounds • Binary Compounds • cation is written first, followed by the anion with and –ide ending • Cs2O  cesium oxide • SrF2 strontium fluoride • CuO  copper(II) oxide • oxygen is always 2- and therefore copper will be 2+ • Cu2O  copper(I) oxide • oxygen is 2- and therefore needed two copper atoms with 1+ charge

  26. SnF2 ? • fluorine is always 1- and therefore tin will be 2+ • tin(II) fluoride • SnS2 ? • sulfur is always 2- and therefore tin will be 4+ • tin(IV) sulfide

  27. Writing formulas for ionic compounds • write symbol of cation and then anion • add subscripts to balance the charges • calcium bromide • Ca2+ and Br1- is CaBr2 • potassium sulfide • K+1 and S2- is K2S • iron(III) oxide • Fe+3 and O2- is Fe2O3

  28. “crisscross” method • the ionic charge number of each ion is crossed over and becomes thesubscriptfor the other ion

  29. Compounds with polyatomic ions • do same as binary compounds • use the name of the polyatomic ion with the mono atomic ion • calcium nitrate  ? • Ca is 2+ and nitrate is 1- • Ca(NO3)2 • Li2CO3  ? • lithium carbonate

  30. Formula to Name Fe(NO3)3 Choose the correct name for the compound 1. Iron trinitrate No, you do not use prefixes 2. iron(I) nitrate No, you have the wrong oxidation number 3. iron(III) nitrite No, you need to review polyatomic ions 4. iron(III) nitrate Very good, click arrow to continue 5. none of the above No, there is a correct answer Polyatomic Ions nextproblem Periodic Chart

  31. Name to Formula sodium chlorite Choose the correct formula for the compound 1. NaCl No, you need to review prefixes 2.NaClO No, you need to review prefixes Very good, click arrow to continue 3. NaClO2 No, you have several errors 4. Na(ClO)2 No, there is a correct answer 5. none of the above nextproblem Prefixes Periodic Chart

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