1 / 59

“Chemical Names and Formulas” – Part I

H 2 O. “Chemical Names and Formulas” – Part I. Atoms and Ions. Atoms are electrically neutral. Because there is the same number of protons (+) and electrons (-). Ions are atoms, or groups of atoms, with a charge (positive or negative)

patriciadouglas
Download Presentation

“Chemical Names and Formulas” – Part I

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. H2O “Chemical Names and Formulas” – Part I

  2. Atoms and Ions • Atoms are electrically neutral. • Because there is the same number of protons (+) and electrons (-). • Ions are atoms, or groups of atoms, with a charge (positive or negative) • They have different numbers of protons and electrons. • Only electrons can move, and ions are made by gaining or losing electrons.

  3. An Anion is… • A negative ion. • Has gained electrons. • Nonmetals can gain electrons. • Charge is written as a superscript on the right. Has gained one electron (-ide is new ending = fluoride) F1- O2- Gained two electrons (oxide)

  4. A Cation is… • A positive ion. • Formed by losing electrons. • More protons than electrons. • Metals can lose electrons Has lost one electron (no name change for positive ions) K1+ Ca2+ Has lost two electrons

  5. Oxidation Numbers • Number given to an element to show how many electrons it has lost, gained or shared when forming a compound • Ex: NaCl • To form this compound: • Na lost 1 e-, Cl gained 1 e-

  6. Assigning Oxidation Numbers • Rule #1 For Groups 1A – 4A: Take number before “A” and add (+) in front • Na in group 1A = +1 O.N. • Rule #2 For Groups 5A-8A: Take number before “A” and subtract 8 from it • Cl in group 7A = 7-8 = -1 O.N.

  7. Oxidation numbers for transition metals (Groups 3-12) • Transition metals have multiple oxidation states • Cu +1 Cu +2 • Fe+2, Fe +3 • Pb +2, Pb +4

  8. Writing Chemical formulas • Write symbol of element with (+) oxidation number first • Write symbol of element with (-) oxidation number Ex. Na+1 Cl -1

  9. Writing Chemical Formulas • If Numbers add up to zero cross out charges and write together Na+1 Cl -1 = NaCl Ca +2 O -2= CaO

  10. Writing Chemical Formulas • If oxidation numbers don’t add up to zero criss-cross the numbers (Al and S) • Al +3S-2 = Al2S3

  11. Predicting Ionic Charges Group 1A: Lose 1 electron to form 1+ ions K1+ H1+ Li1+ Na1+ Rb1+

  12. Predicting Ionic Charges Group 2A: Loses 2 electrons to form 2+ ions Be2+ Mg2+ Ca2+ Sr2+ Ba2+

  13. Predicting Ionic Charges Group 3A: Loses 3 electrons to form 3+ ions B3+ Al3+ Ga3+

  14. Predicting Ionic Charges Group 4A: Neither! Group 4A elements rarely form ions (they tend to share) Do they lose 4 electrons or gain 4 electrons?

  15. Predicting Ionic Charges N3- Nitride Group 5A: Gains 3 electrons to form 3- ions P3- Phosphide As3- Arsenide

  16. Predicting Ionic Charges O2- Oxide Group 6A: Gains 2 electrons to form 2- ions S2- Sulfide Se2- Selenide

  17. Predicting Ionic Charges Group 7A: Gains 1 electron to form 1- ions F1- Fluoride Br1- Bromide Cl1- Chloride I1- Iodide

  18. Predicting Ionic Charges Stable noble gases do not form ions! Group 8A:

  19. Predicting Ionic Charges Group B elements: Many transition elements have more than one possible oxidation state. Note the use of Roman numerals to show charges Iron (II) = Fe2+ Iron (III) = Fe3+

  20. Practice • barium sulfide • NaF • iron (III) oxide • Mn2O5

  21. Practice • barium sulfide - BaS • NaF – sodium fluoride • iron (III) oxide – Fe2O3 • Mn2O5 - manganese (V) oxide

  22. “Chemical Names and Formulas” – Part II

  23. Naming cations • Two methods can clarify when more than one charge is possible: • Stock system – uses roman numeralsin parenthesis to indicate the numerical value • Classical method– uses root word with suffixes (-ous, -ic) • Does not give true value

  24. Naming cations • We will use the Stock system. • Cation - if the charge is always the same (like in the Group A metals) just write the name of the metal. • Transition metals can have more than one type of charge. • Indicate their charge as a roman numeral in parenthesis after the name of the metal

  25. Examples: • (Sodium…Group IA) = Na1+ • (Calcium…Group IIA) = Ca2+ • (Iron (III)…Transition Element) = Fe3+ • (Iron (II)…Transition Element) = Fe2+

  26. Examples: • Potassium ion = K1+ • Magnesium ion = Mg2+ • Copper (II) ion = Cu2+

  27. Naming Anions • Anions are always the same charge • Change the monatomic element ending to – ide • F1- a Fluorine atom will become a Fluoride ion.

  28. Examples: • Chloride = Cl1- • Nitride = N3- • Bromide = Br1-

  29. Examples: • Sulfide ion = S2- • Iodide ion = I1- • Phosphide ion = P3-

  30. Polyatomic ions are… • Groups of atoms that stay together and have an overall charge, and one name. • Usually end in –ate or -ite • Acetate: C2H3O21- • Nitrate: NO31- • Nitrite: NO21- • Permanganate: MnO41- • Hydroxide: OH1- *metal + polyatomic ion = an ionic compound (just like metal + nonmetal)

  31. If the polyatomic ion begins with H, combine the word hydrogen with the other polyatomic ion present… Ex. H1+ + CO32- → HCO31- hydrogen + carbonate → hydrogen carbonate ion

  32. Things to look for: • If cations have ( ), the number in parenthesis is their charge. • If anions end in -ide they are probably off the periodic table (Monoatomic) • If anion ends in -ate or –ite, then it is polyatomic

  33. 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

  34. Naming Binary Covalent Compounds (Molecular Compounds) Two nonmetals • Name each element • End the last element in -ide • Add prefixes to show more than 1 atom

  35. Molecular compounds are… • made of just nonmetals • smallest piece is a molecule • can’t be held together by opposite charge attraction • can’t use charges to figure out how many of each atom (there are no charges present)

  36. Molecular compounds are easier! • Ionic compounds use charges to determine how many of each. • You have to figure out charges. • May need to criss-cross numbers. • Molecular compounds: the name tells you the number of atoms. • Uses prefixes to tell you the exact number of each element present!

  37. Prefixes • 1 = mono- • 2 = di- • 3 = tri- • 4 = tetra- • 5 = penta- • 6 = hexa- • 7 = hepta- • 8 = octa- *KNOW THESE!! • 9 = nona- • 10 = deca-

  38. Prefixes • To write the name, write two words: • One exception is we don’t write mono if there is only one of the first element. • Normally, we do not have double vowels when writing names (oa oo) name Prefix Prefix -ide name

  39. Examples: = dinitrogen monoxide(also called nitrous oxide or laughing gas) • N2O • NO2 • Cl2O7 • CBr4 • CO2 • BaCl2 = nitrogen dioxide = dichlorine heptoxide = carbon tetrabromide = carbon dioxide (This one will not use prefixes, since it is an ionic compound!)

  40. Examples: • diphosphorus pentoxide = P2O5 • sulfur hexafluoride = ?

  41. Naming Ternary Compounds • Contain at least 3 elements • Name the nonmetals as a polyatomic ion • Examples: NaNO3 Sodium nitrate K2SO4Potassium sulfate Al(HCO3)3Aluminumbicarbonate oraluminumhydrogen carbonate

  42. Practice… • lithium oxide • dinitrogen trioxide • Si2Br6 • aluminum carbonate

  43. Practice… • lithium oxide – Li2O • dinitrogen trioxide – N2O3 • Si2Br6 – disilicon hexabromide • aluminum carbonate – Al2(CO3)3

  44. “Chemical Names and Formulas” – Part III

  45. Acids are… • Compounds that give off hydrogen ions (H1+) when dissolved in water • Will start the formula with H. • There will always be some Hydrogen next to an anion. • The anion determines the name.

  46. Rules for Naming acids: • If the anion attached to hydrogen ends in -ide, put the prefix hydro- and change -ide to -ic acid • HCl - hydrogen ion and chloride ion = hydrochloric acid • H2S hydrogen ion and sulfide ion = hydrosulfuric acid

  47. Naming Acids • If the anion has oxygen in it, then it ends in -ate or -ite • change the suffix -ateto -ic acid(use no prefix) • Example: HNO3 Hydrogen and nitrate ions = Nitric acid • change the suffix -iteto -ous acid(use no prefix) • Example: HNO2 Hydrogen and nitrite ions = Nitrous acid

  48. Normal ending ____-ide ____-ate ____-ite Acid name is… hydro-___-ic acid _____-ic acid _____-ous acid Naming Acids

  49. Examples: • HF = hydrofluoric acid • H2SO4 = sulfuric acid • H2SO3 = sulfurous acid

  50. Writing Acid Formulas – in reverse! • Hydrogen will be listed first • The name will tell you the anion • Be sure the charges cancel out. • -ate anioncomes from –ic ending • -ite anion comes from –ous ending

More Related