Formula Writing. (nonmetals) METALS. oxidation number-number assigned to keep track of electron gain or loss. lose electron. gain electron anion

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1 Formula Writing oxidation number-number assigned to keep track of electron gain or loss lose electron + cation METALS - gain electron anion (nonmetals) cation is written first anion is second positive ion first negative ion second Binary Compound Compound made of only two elements (Usually metal with nonmetal) Use Criss-Cross Definition Polyatomic Compounds Compound made of 3 or more elements (Usually table E, polyatomic ions) Use Criss-Cross

2 Forming Cations Metals lose electrons to be stable. Metal ions are positively charged because they have more positive protons than negative electrons. potassium potassium ion K K + + e -

3 Naming Cations Cations are named the same as their parent atoms, as shown here: 6-3

4 6-4 Forming Anions Nonmetals gain electrons to be stable. Nonmetal ions are negatively charged because they have fewer positive protons than negative electrons. chlorine chloride ion Cl + e - Cl -

5 6-5 Naming Anions Monatomic anions use the stem of the element s name and the ending changed to ide.

6 Ion Charges Metals on the left side of the periodic table form only one ion. Metals in group 1 and 2 their charge is their group number. Many metals form more than one ion. Often these are the transition metals. The charge of a nonmetal is = to its group number Copyright 2011 John Wiley & Sons, Inc

7 6-7 Your Turn! Calcium is an element in group 2A. Which of the following statements is correct about calcium forming an ion? a. Ca gains two electrons, forming Ca 2+ b. Ca gains two electrons, forming Ca 2- c. Ca loses two electrons, forming Ca 2- d. Ca loses two electrons, forming Ca 2+

8 6-8 Your Turn! Phosphorus is a nonmetal in group 5A. The charge on the phosphide ion is a. -3 because the element lost 3 electrons. b. -3 because the element gained 3 electrons. c. +3 because the element lost 3 electrons. d. +3 because the element gained 3 electrons.

9 Binary Compound Second element name ends in -ide Definition Polyatomic Compounds Second element can end in - ate - ite - ium ONLY - ide s : peroxide, hydroxide, cyanide Aluminum Sulfide 1. Look up symbol for the element on Table S Al S 2. Write the oxidation number, (which are found on the Periodic Table, above each symbols as a superscript): Al +3 S Crisscross the oxidation numbers and omit the charge signs. Write the numbers below the symbols as subscripts. Al 2 S 3 Note: The crisscrossing of the oxidation numbers conserves the charge. The sum of the oxidation numbers of all of the atoms in a compound is always zero. 4. When each element has the same oxidation number, these numbers are dropped and the formula is correct as written in step 1. Aluminum Sulfate 1. Look up symbol for the element on Table S; polyatomic ion on Table E Al SO 4 2. Write the oxidation numbers, which are found on the Periodic Table, above each symbols as a superscript: Al +3 SO Place the polyatomic ion in parentheses Crisscross the oxidation numbers and omit the charge signs. Write the numbers below the symbols as subscripts. Al 2 (SO 4 ) 3 The sum of the oxidation numbers of all of the atoms in a compound is always zero. 4. When each element has the same oxidation number, these numbers are dropped and the formula is correct as written in step 1.

10 Sodium Sulfide Na +1 S 2- Na +1 S 2- -ide on PT Sodium Sulfate Na +1 SO ate on Table E Na 2 S ***MUST use parentheses hereif it s more than one!*** Na 2 SO 4

11 6-11 Writing Formulas for Ionic Compounds Write the formulas for the compounds containing the following ions: 1. Al 3+ and F - 2. Ca 2+ and N 3-3. K + and Cl - 4. Mg 2+ and I - AlF 3 Ca 3 N 2 KCl MgI 2

12 6-12 Your Turn! What is the correct formula for the compound beryllium (Be) fluoride (F)? a. BeF b. Be 2 F c. BeF 2 d. Be 2 F 2

13 6-13 Your Turn! What is the correct formula for the compound silver (Ag) sulfide (S)? a. AgS b. AgS 2 c. Ag 2 S d. 2AgS

14 Naming Compounds Ionic compounds Naming Binary Compounds 1. The element with the positive ionic charge is written first. Polyatomic Ions Look up the name of the polyatomic ion on chart table E 2. The second word is formed by changing the ending of the name of the element to ide. Example bromine becomes bromide. Metals usually have positive ionic charges Nonmetals (when combined with metals) have negative charges. NaCl sodium chlorine sodium chloride When polyatomic ion is second 1. write the name of the first element 2. write the name of the polyatomic ion Na 2 SO 4 Sodium sulfate If polyatomic ion first 1. look up ion name 2. follow ending for binary compounds NH 4 Cl ammonium chlorine ammonium chloride

15 6-15 Your Turn! What is the correct name for CdF 2? a. Cadmium flourine b. Cadmium flouride c. Cadmium fluorine d. Cadmium fluoride

16 Naming & Writing Compounds Elements with more than one positive oxidation number (Transition Metals) (This is called the Stock System) When the oxidation number varies we us a Roman numeral in parentheses to indicate the charge. Roman number is used for the positive element only!!! (I, II, III, IV, V, VI, VII, VIII, IX, X) FeO Iron (II) oxide Fe 2 O 3 Iron(III) oxide **TRANSITION METALS!!!!! Alternative method for compounds ALL NON METALS ONLY!!! We can also use prefix to indicate the number of each element mon 1, di 2, tri 3, tetra 4, penta 5, hexa 6, hepta 7, octa 8, non 9, deca 10 ***No criss cross*** If the first element is 1, don t write mono Carbon monoxide CO dinitrogen trioxide N 2 O 3

17 6-17 Naming Binary Ionic Compounds 1. Write the name of the cation. 2. Write the charge on the cation as a Roman numeral in parenthesis. 3. Write the name of the anion with suffix ide. CoCl 3 Fe 3 P 2 CuO SnBr 4 cobalt(iii) chloride iron(ii) phosphide copper(ii) oxide tin(iv) bromide

18 6-18 Naming Binary Ionic Compounds More Practice 1. CoCl 3 2. K 2 S 3. HgF 2 4. AgBr 5. Fe 3 P 2 6. PbI 4 cobalt(iii) chloride potassium sulfide mercury(ii) fluoride silver bromide iron(ii) phosphide lead(iv) iodide

21 6-21 Your Turn! Sulfate is SO Name the compound FeSO 4. a. iron sulfate b. iron(i) sulfate c. iron(ii) sulfate d. iron(iv) sulfate

23 6-23 Your Turn! Sulfur dioxide is a. SO b. S 2 O c. SO 2

24 Chemical Bonding Chemical bonds are the forces that hold atoms together in a compound. when atoms bond they release energy and become more stable Ionic Covalent Metallic

25 Ionic Bonds Metal/nonmetal Transfer e - e - is transferred from the metal to the nonmetal QuickTime and a TIFF (Uncompressed) decompressor are needed to see this picture. EN difference greater than 1.7 Greater the EN difference, greater the ionic character

26 11-26 Your Turn! Metals generally form ions by a. Gaining electrons, forming positive ions b. Losing electrons, forming positive ions c. Gaining electrons, forming negative ions d. Losing electrons, forming negative ions Copyright 2011 John Wiley & Sons, Inc

27 QuickTime and a TIFF (Uncompressed) decompressor are needed to see this picture. hard Ionic Solid crystalline high melting and boiling points do not conduct electricity in the solid state do conduct electricity in the molten (liquid) or aqueous state (aq)-electrolyte (ions) NaCl

28 11-28 Ionic Bond Formation An ionic bond is the attraction of oppositely charged particles. Na + Cl [Na] + [ Cl ] -

29 NaCl Crystal 11-29

Formation of Magnesium Chloride 11-30 Mg needs to lose 2 electrons: [Ne]3s 2 Cl needs to gain

30 Formation of Magnesium Chloride Mg needs to lose 2 electrons: [Ne]3s 2 Cl needs to gain 1 electron: [Ne]3s 2 3p 5 We will need to transfer 2 electrons from Mg to Cl. 2 Cl are needed!

31 Covalent Bond 2 nonmetals Share e - Nonpolar Same nonmetals Share the electrons equally Difference of 0 Polar Different nonmetals Share the electrons unequally Difference of Coordinate Moochers one atom donates a pair of electrons to be share, the other contributes none Cl 2 H 2 0 CO 2 NH 4 + H 3 O +

32 QuickTime and a TIFF (Uncompressed) decompressor are needed to see this picture. QuickTime and a TIFF (Uncompressed) decompressor are needed to see this picture. QuickTime and a TIFF (Uncompressed) decompressor are needed to see this picture.

boiling points C 6 H 12 O 6 CO 2 HCl Hard crystalline Are poor conductors

33 Molecular Substance Network Solid are brittle in the solid form All 3 states of matter are poor conducts of heat and electricity Low melting and boiling points C 6 H 12 O 6 CO 2 HCl Hard crystalline Are poor conductors of heat and electricity High melting boiling points C-diamond SiO 2 -quartz/sand SiC

34 Metallic Bonds metals Mobile e - Metals Electrons move freely from one atom to another. sea of mobile electrons good conductors of electricity and heat in any state malleable ductile high melting and high boiling points

35 Venn diagram Ionic Covalent

36 Venn diagram Ionic Covalent Forms when one atom donates electrons to another Exist between ions Holds ions together in an ordered 3-d array, called an ionic crystal Typically exist between atoms on opposite sides of the periodic table Results from electrostatic attraction between opposite charges Are forces acting between atoms to hold them together Can form when atoms make contact Either absorb or release energy when formed Create new species with chemical and physical properties unlike constituent atoms Form because atoms want to have complete outer shells Forms when atoms share 2,4,6 electrons Builds molecules Can be polar or non-polar Exist between neutral atoms Forms when atoms that tend to gain electrons come into contact with one another Generally form between atoms in the upper right hand corner of the periodic table

37 Lewis Dot Structure Octet Rule molecules and ions need to have eight electrons in their valance level as the result of bond formation Hydrogen and helium want 2 Rules for drawing an atom. Shows the number of valence electrons for an individual atom Find the number of valence e Put 2 on top Put 1 on each side double up

11-38 Lewis Structures of Atoms Figure 11.4 Lewis structures of the first 20 elements.

39 11-39 Predicting Formulas of Ionic Compounds Elements within a group behave similarly because their valence electron configuration is the same. If sodium oxide is Na 2 O, then oxides of other Group IA elements will also exist in a 2:1 ratio: Li 2 O, K 2 O, Rb 2 O If sodium oxide is Na 2 O, then sulfides of the Group IA elements will also exist in a 2:1 ratio. Na 2 S, K 2 S, Rb 2 S Copyright 2011 John Wiley & Sons, Inc

40 Ionic Metal/nonmetal OR an ION (just choose half)! Write the formula-tell how many of each atom you need Metal: no dots positive charge [ ] Nonmetal: 8 dots negative charge [ ] Aluminum bromide

41 11-41 Your Turn! How many valence electrons are present in an atom of aluminum in the ground state and what charge will it form when it loses those electrons? a. 3, +3 b. 3, -3 c. 5, +3 d. 1, +1 e. 13, +3 Copyright 2011 John Wiley & Sons, Inc

42 11-42 Your Turn! How many valence electrons are present in an atom of bromine in the ground state and how many does bromine need to gain to have the same electron configuration as a noble gas? a. 1, 7 b. 2, 6 c. 3, 5 d. 7, 1 Copyright 2011 John Wiley & Sons, Inc

43 Covalent ***MOLECULE!!!!!!!*** 2 non metals 1. Determine the total number of valence e. 2. Draw the skeletal structure. (If only one atom, it will be in the center-central atom.) 3. Put 2 e between each atom. 4. Complete the octet rule for all non-central atoms. 5. Put remaining e on the central atom. 6. Check work. 7. If not enough electrons, make double or triple bonds.

44 11-44 The Covalent Bond Molecules exist as discrete units held together by covalent bonds. A covalent bond consists of a pair of electrons shared by two atoms. Figure 11.8 The formation of a hydrogen molecule from two hydrogen atoms. The two 1s orbitals overlap, forming the H 2 molecule.

45 Shapes and Polarity of Molecules (ALL NON-METALS!!!!) Symmetrical - non polar - opposite sides match Cross test + Determining Polarity Asymmetrical - polar - opposite sides don t match ** MUST be symmetrical in both directions to be considered Non- Polar. SNAP

46 Shape Definition Example Ball and Stick Model linear Check symmetry 2 atoms connected 3 atoms in a line HBr H Br CO 2 O C O tetrahedral Check symmetry 1 central atom with 4 atoms around it No unpaired e around central atom CH 4 (non polar) CH 3 F (polar) H H C H H pyramidal Always polar 1 central atom with 3 atoms around the central Atom 1 pair of e not shared NH 3 N H H H bent Always polar 1 central atom, with 2 other atoms off the central atom 2 pairs of e not shared H 2 O H O H

11-47 Molecular Shape Figure 11.12 Geometric shapes of common molecules.

47 11-47 Molecular Shape Figure Geometric shapes of common molecules. Each molecule is shown as a ball and stick model (showing the bonds) and as a spacefilling model (showing the Copyright 2011 John Wiley & Sons, Inc shape).

48 Intermolecular Forces Are the forces that exist between individual molecules--weaker than a bond Hydrogen Bonding Dipole - Dipole Van der Waals between molecules containing Hydrogen bonded with F, O, N small highly electronegative H-F **H-F dipole - polar molecule H-Br Atom with the higher EN will be negative. between polar molecules H-Br *****H-Br London Dispersion between non polar molecules Diatomic elements Noble gases Organic-C Force is stronger: 1. Closer they are 2. Heavier they are CH 4 ****CH 4 Stronger the intermolecular force, higher the melting and boiling point Ionic > H-bond > Molecular (Covalent molecules)

49 Molecule- Ion Attraction Ionic solids when placed in water dissociate ( separate) due to the attraction of opposite charges Polar and ionic (aq) NaCl (aq) Na + Cl -

52 11-52 Your Turn! Is the molecule NF 3 polar or nonpolar? a. Polar, because it has polar bonds arranged symmetrically around the N. b. Polar, because it has polar bonds arranged asymmetrically around the N. c. Nonpolar, because it has polar bonds arranged symmetrically around the N. Copyright 2011 John Wiley & Sons, Inc

IB Chemistry. Chapter 4.1

IB Chemistry. Chapter 4.1 IB Chemistry Chapter 4.1 Chemical Bonds Atoms or ions that are strongly attached to one another Chemical bonds will form if potential energy decreases (becomes more stable) 2 Valence Electrons Valence