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Chapter 4 The Structure of Matter

Chapter 4 The Structure of Matter

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Chapter 4 The Structure of Matter

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  1. Chapter 4 The Structure of Matter • I. 4.1 Compounds and Molecules • II. 4.2 Ionic and Covalent Bonding • III. 4.3 Compound Names and Formulas • IV. 4.4 Organic Chemistry

  2. I. 4.1 Compounds and Molecules • A. What are Compounds? • 1. Chemical bonds are the attractive force that holds atoms or ions together in compounds. • 2. Compounds always have the same chemical formula • a. com - with, together, jointly • b. pound - put, position • c. water H20 • d. table sugar C12H22O11 • e. salt NaCl

  3. B. A chemical formula shows the types and numbers of atoms or ions making up the simplest unit of the compound. 1. There is a difference between CO and CO2 a. each is made up of C and O but one has 2 O atoms

  4. 2. The same for H2O and H2O2 (hydrogen peroxide) 3. Compounds are always made up of the same elements in the same proportion. 4. The formula can tell us what atoms a compound is made of but does not reveal how they are connected.

  5. 5. The chemical structure show the arrangement of bonded atoms or ions within a substance. a. Two terms are used to specify the relative positions of atoms to each other in a compound. (1) Bond length - gives the distance between the two nuclei of the atoms (2) Bond angles tell how these atoms are oriented when you have three or more atoms in the compound.

  6. C. Models of compounds can help us to see a compounds structure. 1. Ball and stick a. the ball represents the atom b. the stick represents the bonds. c. hard to see the relative size of the atoms

  7. 2. Structural formula use the chemical symbol to represent the atoms a. hard to see the relative size of the atoms 3. Space filled models a. shows the relative size of the atoms b. H2O - hydrogen atoms taking up less space than the oxygen atoms c. hard to see the bond angle and lengths

  8. D. Structure effects properties 1. Some compounds form crystals when the chemical bonding is repeated over and over again to form very strong structures.

  9. a. Quartz SiO2 (1) bond angle 109.5o (2) makes a very strong, rigid structure (3) rocks made of quartz are very hard and inflexible (4) the reason why the melting and boiling points of quartz is so high (a) melting point 1700oC (b) boiling point 2230oC 2. Some networks are made of bonded ions a. NaCl crystal is made of tightly packed Na+ ions and Cl+ ions b. this strong attraction produced a high melting and boiling point (1) melting point 801oC (2) boiling point 1413oC

  10. 3. Many other compounds due to their structure have very weak attractions between their molecules a. sugar C12H22O11 b. melts around 185-186oC 4. Comparing strengths of attraction between molecules a. solids - strongest b. liquids - medium c. gases - weakest

  11. Work 1. p 114 1-7write questions and answers

  12. II. 4.2 Ionic and Covalent Bonding • A. Ionic Bonds • 1. defined - a bond formed between oppositely charged ions. • 2. There is an electron transfer • a. one gains electron(s) • b. one loses electron(s) • 3. mostly between metals and nonmetals

  13. 4. These form polar molecules which will form a network of ions a. the positive side attracts the negative side (1) how salt crystals are formed 5. Formula unit is the smallest ratio of ions in ionic compounds a. Na+1Cl-1 or Ca+2F2-1 b. When melted or dissolved in H2O ionic compounds will conduct electricity because the ions are free to move. c. As solids the ions are locked so tightly that they do not conduct electricity.

  14. B. Metallic Bonds 1. defined - a bond formed by the attraction between positively charged ions and the electrons around them. 2. Metal to metal a. example: Cu

  15. 3. This allows the atoms to a. conduct electricity (1) electrons are free to move from one atom to another atom (2) be more flexible to bend and stretch without breaking. (a) atoms can slide past each other without breaking their bonds

  16. C. Covalent Bonds 1. defined - a bond formed when atoms share one or more pairs of electrons. 2. often formed between nonmetal atoms a. can be solids, liquids, or gases b. usually low melting points except for compounds that form network structures like SiO2

  17. 3. Do not conduct electricity because the molecules remain intact when melted or dissolved in H2O. 4. Electrons are shared not transferred with the nucleus of each atom equally attracting the electrons.

  18. a. This results in two types of molecules (1) polar - NH3 (2) nonpolar - CO2 b. Atoms may share more than one pair of electrons (1) O=O (2) N=N c. polar covalent bonds are formed between two different atoms where the shared electrons are attracted to one nucleus more than the other

  19. D. Poly atomic Ion 1. defined - an ion made up of two or more atoms that are covalently bonded and that act like a single ion. 2. most names end in -ite and -ate. a. -ide = the anion named only (1) CN-1 - cyanide (2) OH-1 - hydroxide b. -ite = the anion with one less oxygen (1) SO3-2 - sulfite c. -ate = the anion with one more oxygen (1) SO4-2 - sulfate

  20. 3. Use parentheses around them when more than one is needed in the formula. a. (NH4)2SO4 - ammonium sulfate b. NH4NO3 - ammonium nitrate 4. Learn the poly atomic ions with there name, symbol, and charge on page 122 as follows: acetate C2H3O2-1, carbonate CO3-2, chlorate ClO3-1, hydroxide OH-1, nitrate NO3-1, nitrite NO2-1, cyanide CN-1, phosphate PO4-3, sulfate SO4-2, sulfite SO3-2, and ammonium NH4+1

  21. Page 122 Questions 1-7 Write question and answers Due at end of class

  22. III. 4.3 Compound Names and Formulas • A. Compounds have names that distinguish them from other compounds and elements. • 1. BaF2 - barium fluoride vs. BF3 - boron trifluoride

  23. B. Ionic Compounds 1. Include the name of the ions of which they are composed a. The cation (positive) is usually the name of the element (1) K+ - potassium (2) Ba+2 - barium

  24. b. The transition elements we use the element name plus a roman numeral for the oxidation number in that compound. (1) Fe+3 - iron III (2) Fe+2 - iron II (3) Ti+4 - titanium IV

  25. c. For the anion (negative) we use the root of the element name and attach an ending (1) -ide - only the root element makes up the anion (2) iron II oxide FeO (3) fluoride - F-1; chloride - Cl-1; bromide – Br -1; sulfide - S-2 (4) remember the -ites and -ates have oxygen with the root element (a) sulfate - SO4-2; phosphate - PO4-3

  26. 2. Writing formulas a. List the symbols for each ion. (1) example: for aluminum fluoride Al F b. Write the symbols for the ions and their oxidation number with the cation first. (1) Al+3 F-1 c. Find the least common multiple of the ions charges. (1) for 3 and 1 it is 3 (2) you will need 3 positive charges and 3 negative charges d. Write the chemical formula, indicating with subscripts how many of each ion is needed to make a neutral compound. (1) +3 -3 = 0 Al+3 F3-1

  27. 3. Practice p. 125 1-4

  28. 4. Some covalent compounds will form more than one compound with the same two elements a. We use a numeral prefix to indicate the number of ions in that compound. Page 126 b. example: CO - carbon monoxide and CO2 carbon dioxide

  29. C. Empirical formula 1. defined - the simplest chemical formula of a compound that tells the smallest whole number ratio of atoms in the compound. D. Molecular formula 1. defined - a chemical formula that reports the actual numbers of atoms in molecule of a compound. a. in some cases the molecular formula is the same as the empirical formula

  30. (1) formaldehyde - the empirical formula is CH2O and a molecular formula of CH2O (2) acetic acid - the empirical formula is CH2O and a molecular formula of C2H4O2 (3) glucose - the empirical formula is CH2O and a molecular formula of C6H12O6

  31. E. Gram molecular mass of a compound

  32. 1. Ba(OH)2 Elementatomsmolar mass/atommolar mass all atoms Ba 1 x 137.33 g/mole = 137.33 g/mole O 2 x 16.0 g/mole = 32.0 g/mole H 2 x 1.0 g/mole = 2.0 g/mole 171.33 g/mole Ba(OH)2

  33. Ni3(PO4)4 Elementatomsmolar mass/atommolar mass all atomsNi 3 x 58.69 g/mole = 176.07 g/moleP 4 x 30.97 g/mole = 123.88 g/moleO 16 x 16.0 g/mole = 256.0 g/mole 555.95 g/mol Ni3(PO4)4

  34. 3. class work a. FeI2 b. MnF3 c. CrCl2

  35. IV. Organic Chemistry • A. Polymers • 1. defined - a large organic molecule made of many smaller bonded units • a. poly - many • 2. properties are determined by its structure • a. some long thin chains • b. some tangled like a bowl of spaghetti

  36. 3. most of your plastic and rubber products are polymers a. elastic - return to original shape (1) rubber bands b. non elastic - will not return to original shape (1) plastic soft drink bottles

  37. Home work F. page 128 1-4; 6-7