Compounds & Bonding

1. Compounds & Bonding Chapters 6 & 7

2. V a l e n c e E l e c t r o n s • E l e c t r o n s i n t h e o u t e r e n e r g y l e v e l a r e c a l l e d v a l e n c e e l e c t r o n s • I t i s t h e s e e l e c t r o n s t h a t d e t e r m i n e t h e f o r m a t i o n o f c h e m i c a l b o n d s

3. V a l e n c e E l e c t r o n s • C e r t a i n n u m b e r s o f v a l a n c e e l e c t r o n s a r e m o r e s t a b l e t h a n o t h e r s . • A t o m s w i l l g a i n o r l o s e e l e c t r o n s t o b e c o m e m o r e s t a b l e .

4. Bonds Between Atoms Polyatomic Ions Ionic Covalent Metallic Network Solids Molecular Substance Polar Coordinate Covalent Nonpolar What are we going to learn about???

5. Marriage Forming of a bond is like marriage The breaking of a bond relates to a divorce. • More stable • exothermic Divorce • Less stable • Endothermic

6. C h e m i c a l B o n d T y p e s • I o n i c • C o v a l e n t • M e t a l l i c

7. Examples

8. Types of Bonds • There are two types of bonds – ionic & covalent • Ionic bonds – a bond formed from a force between two opposite charges (+ and -). • Covalent bonds – a bond formed from sharing electrons between two atoms. • Single bonds = one bond between only two atoms • Multiple bonds = more than one bond between atoms

9. What are some characteristics of an ionic bond? • Crystalline (salt crystals) at room temperatures • Have higher melting points and boiling points compared to covalent compounds • Conduct electrical current in molten or solution state but not in the solid state • Polar bonds

10. What are some characteristics of a covalent bond? • Covalent bonds have definite and predictable shapes. • Very strong • Low melting and boiling points

11. Types of Bonds • Ionic bonds are made from metal and a nonmetal. • Covalent bonds are made from two nonmetals. • Polar molecules have a (+) and a (–) end to them (like ionic but weaker). • Nonpolar molecules have their electrons shared evenly so that there are no ends like a magnet.

12. There are five different categories associated with covalent bonds. What are the 5 different categories? Covalent Network Solids Molecular Substance Polar Coordinate Covalent Nonpolar

13. First, we are going to look at Polar Covalent… c What is polar covalent? -Polar covalent is a description of a bond that has an uneven distribution of charge due to an unequal sharing of bonding electrons. The boy is not equally sharing with anyone else but rather taking all the food for himself.

14. Next, we are going to look at Non-Polar Covalent… What is non-polar covalent? -Non polar covalent is a covalent bond that has an even distribution of charge due to an equal sharing of bonding electrons. This couple is non- polar because they are sharing the drink equally between them.

15. Next, we are going to look at Molecular Substances… What is a molecular substance? -A molecular substance is a substance that has atoms held together by covalent bonds. Name 2 Characteristics of a Molecular Substance. • Weak • Low melting and boiling points

16. Next, we are going to look at Coordinate Covalent… What is a Coordinate Covalent Bond? -A coordinate covalent bond is a bond formed when one atom donates both electrons that are shared. People donate their blood to help others just like atoms “donate” electrons to form stable octets.

17. Polyatomic Bonds Polyatomic ions usually have a charge because the collection of atoms has either gained an extra electron or else it has lost an electron. What is a Polyatomic Bond? - A polyatomic bond is charged group of covalently bonded atoms. It is made up of more than one atom.

18. Now, we are going to look at Network Solids… What is a Network Solid? Diphenylglycoluril assembles into a unique, two-dimensional hydrogen bonding network in the solid state, while exhibiting a twisted molecular structure. -A network solid is a solid that has covalently bonded atoms linked in one big network or one big macromolecule. Name 3 Characteristics of a Network Solid. • Poor conductors of heat and electricity • Hard / Strong • High melting and boiling points

19. Just as a summary to what each bond looks like…

20. P r e d i c t i n g B o n d T y p e s • W i l l t h e s e p a i r s f o r m i o n i c o r c o v a l e n t b o n d s ? • s o d i u m & c h l o r i n e • c a l c i u m & o x y g e n • c a r b o n & o x y g e n • a l u m i n u m & s u l f u r

21. Writing Chemical Formulas • Binary Ionic Compounds – “bi” means two, compounds made of two elements • Example: potassium + iodine potassium iodide K+ + I- KI Oxidation number means charges on the “ions” (which means charges). Let’s practice!! beryllium + selenium  beryllium selenide

22. Writing Chemical Formulas • Polyatomic Ions – “poly” means many, compounds made with two or more elements • Ex: ammonium + chlorine  ammonium chloride NH4+ + Cl-NH4Cl • (DO NOT BREAK APART POLYATOMIC ELEMENTS – THEY TRAVEL TOGETHER!!) • Let’s practice!! • carbonate + magnesium  magnesium carbonate

23. Metallic Bonding Name 4 Characteristics of a Metallic Bond. What is a Metallic Bond? - A metallic bond occurs in metals. A metal consists of positive ions surrounded by a “sea” of mobile electrons. • Good conductors of heat and electricity • Great strength • Malleable and Ductile • Luster This shows what a metallic bond might look like.

24. Naming Ionic Compounds • Use the whole first name (+ element) and the root of the second name (- element). Change the ending of the second element to -ide. • If there is a polyatomic, the name DOES NOT change!!! • Let’s practice!! CaCl2 AlN BPO4

25. Covalent Nomenclature Rules • Prefix System (binary compounds) 1. Less e-neg atom comes first. 2. Add prefixes to indicate # of atoms. Omit mono- prefix on first element. 3. Change the ending of the second element to -ide.

26. Naming Covalent Molecules • Use prefixes to tell how many atoms of each element in the compound • Ex: CO2, N2O4, CCl4 • Write the formula of the following from the name: sulfur dichloride, phosphorus hexachloride, dihydrogen monoxide

27. Naming Covalent Molecules • NCl4 • N2O • SF6 • nitrogen tetrachloride • dinitrogen monoxide • sulfur hexafluoride

28. Writing Molecular Structures • arsenic trichloride • dinitrogen pentoxide • tetraphosphorus decoxide • AsCl3 • N2O5 • P4O10

29. Covalent Exceptions • The Seven Diatomic Elements Br2 I2 N2 Cl2 H2 O2 F2 H N O F Cl Br I

30. Bond Polarity • Most bonds are a blend of ionic and covalent characteristics. • Difference in electronegativity determines bond type.

31. Bond Polarity Examples: • Cl2 • HCl • NaCl 3.0-3.0=0.0 Nonpolar 3.0-2.1=0.9 Polar 3.0-0.9=2.1 Ionic

32. REMEMBER….. • Electronegativity Trend (p. 161) • Increases up and to the right. • There are values to each participating element

33. Chemical Changes • Chemical reaction – a change in which one or more substances are converted into new substances reactants  products • Conservation of mass – starting mass of the reactants must equal the final mass of the products -Ex: HgO  Hg + O 10.0g = 9.3g + ?g Chemical equation Review symbols

34. Balancing Chemical Equations • Conservation of mass states that the reactants and the products must equal. • Balancing charges on ions sometimes makes the products equal the reactants. • Coefficients (big numbers) are used to multiply the compounds and balance the mass on each side of the chemical equation.

35. Balancing Chemical Equations • __ Al + __O2 __Al2O3 • __ H2 + __ O2 __H2O • __ S + __ O2  __SO3

36. Classifying Chemical Reactions • Synthesis A + B AB • Decomposition AB A + B • Single displacement A + BC AC + B • Double displacement AB + CD  AD + BC

37. Organic Compounds • Organic compounds are made of mostly carbon and hydrogen atoms. • Naming these compounds starts with the # of carbon atoms present using a particular prefix. • Then the ending depends on the type of bonds made.