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Nomenclature : Naming Chemicals

Nomenclature : Naming Chemicals. PO 4 3- phosphate ion. HC 2 H 3 O 2 Acetic Acid. C 2 H 3 O 2 - acetate ion. Before naming…. Some things you MUST know to be successful…. You really need to commit these things to memory. Ions. Atoms or groups of atoms with a charge.

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Nomenclature : Naming Chemicals

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  1. Nomenclature: Naming Chemicals PO43- phosphate ion HC2H3O2 Acetic Acid C2H3O2- acetate ion

  2. Before naming…. • Some things you MUST know to be successful…. You really need to commit these things to memory

  3. Ions • Atoms or groups of atoms with a charge. • Cations- positive ions - get by losing electron(s). • Anions- negative ions - get by gaining electron(s). • Ionic bonding- held together by the opposite charges. (usually a metal and a nonmetal) • Ionic solids are called salts. • Salts are electrolytes; they conduct electricity when dissolved in water (aq.)

  4. Metals Conductors of heat and electricity Make cations (lose e- to become + charged) Malleable (made into sheets) Ductile (made into wire)

  5. Nonmetals Are a brittle solid or a gas Make anions (gain e- to become - charged) Covalently bond to each other

  6. Semi-metals (AKA Metalloids) • Characteristics of both metals and nonmetals • More metallic as you go down PT

  7. Alkali Metals

  8. Alkaline Earth Metals

  9. Transition metals

  10. Inner Transition Metals

  11. Halogens

  12. Noble Gases

  13. Common Ions of Elements +1 +3 +/-4 +2 -3 -2 -1 Variable, always +

  14. Predicting Charges on Monatomic Ions KNOW THESE !!!! +1 +2 -3 -2 -1 0 Cd+2

  15. Polyatomic Ions • Groups of covalently bonded atoms that have a charge. * NO3- :nitrate ion * NO2- :nitrite ion • Yes, you have to memorize them. • Listed in your resource handbook: memorize the required list!!!!

  16. Patterns for Polyatomic Ions • -ate ion • chlorate = ClO3- • -ate ion plus 1 O  same charge, per- prefix • perchlorate = ClO4- • -ate ion minus 1 O  same charge, -ite suffix • chlorite = ClO2- • -ate ion minus 2 O  same charge, hypo- prefix, -ite suffix • hypochlorite = ClO-

  17. Polyatomic Ions You can make additional polyatomic ions by adding a H+ to the ion! • CO3-2 is carbonate • HCO3– is hydrogen carbonate • PO4 3- is phosphate • HPO4 is hydrogen phosphate • H2PO4 is dihydrogen phosphate • HSO4–2 is hydrogen sulfate

  18. The 3 types of Chemical Bonds:Ionic, Covalent, & Metallic Electronegativity and Bond type • Bond type can be determined by the difference in electronegativity between the bonds involved. • Differences of: • ≥ 2 = ionic • 0.5 – 1.9 = polar covalent • ≤ 0.4 = nonpolar covalent • Metals bonded to other metals are metallically bonded, regardless of the difference in electronegativity .

  19. Metallic bonds • The atoms of metals are held together when the atom’s valence electrons float around the nuclei of the metals – the “sea of electrons” • Electrostatic forces keep everything together

  20. The 3 types of Chemical Bonds:Ionic, Covalent, & Metallic • Ionic—complete transfer of 1 or more electron from one atom to another (or another group) • one loses one or more e-, the other gains those e- • Atoms involved are • a metal and either a non-metal or a polyatomic ion • The cation and anion are attracted to each other by electrostatic attraction .

  21. Ionic compounds are neutral • Ionic compounds are neutral • That is, they have no overall charge • This is because the number of electrons that are given up by the metal is the same number of electrons that are gained by the anion for the formula. • Formulas reflect this neutrality- the charges on the individual ions are not written in because they cancel out overall for the compound

  22. CATION + ANION ---> COMPOUND COMPOUNDS FORMED FROM IONS Na+ + Cl---> NaCl A neutral compound requires equal number of + and - charges.

  23. Covalent Bonds • 2, 4, or 6 valence electrons that are shared between atoms • We are going to name only simple covalent compounds that have 2 elements involved

  24. Most bonds are somewhere in between ionic and covalent • Because not all atoms share e- equally • The conventions of naming assume absolute difference in bond types • Metals bonded to nonmetals or polyatomic ions are classified as having ionic bonds* • Materials made out of all non-metals are classified as having covalent bonds* • * semimetals are not a classification in naming; you need to treat the elements that are on the right of the line as non-metals, and those on the left as metals. • More on this when we talk about bonding

  25. Naming things: • If there is only one element present, name it. Atomic substances do not require “special” naming. • For anything with more than one element, remember that there is ONE MAIN THING to look for: • Is there a metal first?

  26. So… • Look to see if there is a metal first in the formula • Again, semimetals are not a classification in naming; you need to treat the elements that are on the right of the line as non-metals, and those on the left as metals. • If there are only metals, name both metals • (metallic bonding; nothing else need be done) • If ONLY the first element is a metal, then the compound is an ionic compound • Nonmetals only signify a covalent compound • There is a flow chart in your handbook to help!

  27. Naming ionic compounds: • Remember that those are compounds that have a metal first in the formula*, and then a nonmetal or a polyatomic ion. • *Two exceptions to this rule: • Compounds that start with either ammoniums (NH4+) or hydronium (H3O+) • We can handle these as simple binary (2 element) and ternary (more than two element) compounds

  28. General information for naming ionic compounds • If the cation is monatomic- Name the metal (cation). • Use Roman Numerals for transition metals (ONLY) after the metal • If the cation is polyatomic- name it. • If the anion is monatomic- name it but change the ending to –ide. • If the anion is poly atomic- just name it • Practice.

  29. Specifics for binary ionic compounds: Example: CaCl2, or calcium chloride Name the cation first, then the anion root with an –ide suffix For CaCl2, the monatomic cation is Ca2+ , calcium, and the monatomic anion is Cl- , named chloride. We use chloride because the root for chlorine is chlor, and we use = root + -ide for the second element in binary compounds CaCl2 = calcium chloride

  30. Practice Naming Binary Ionic Compounds • Examples: NaCl ZnI2 Al2O3

  31. Learning Check Complete the names of the following binary compounds: Na3N KBr Al2O3 MgS

  32. If the Metal is a Transition Metal… Transition metals are Type II Cations, and are elements that can have more than one possible charge. They MUST have a Roman Numeral to indicate the charge on the individual ion. 1+ or 2+ 2+ or 3+ Cu+,Cu2+ Fe2+, Fe3+ copper(I) ion iron(II) ion copper (II) ion iron(III) ion

  33. Type II Cations These elements REQUIRE Roman Numerals because they can have more than one possible charge: anything except Group 1A, 2A, Ag, Zn, Cd, and Al (You should already know the charges on these!) Or another way to say it is: Transition metals and the metals in groups 4A and 5A (except Ag, Zn, Cd, and Al) require a Roman Numeral. FeCl3(Fe3+) iron (III) chloride CuCl (Cu+ ) copper (I) chloride SnF4 (Sn4+) tin (IV) fluoride PbCl2 (Pb2+) lead (II) chloride Fe2S3 (Fe3+) iron (III) sulfide You will appreciate this more when we go from names to formulas!

  34. Type II Cations Some Type II cations have a name using the “old” system as well as the “new system”. The old system, still widely used, adds to the root or stem of the Latin name of the metal the suffixes –ous and –ic. These represent the lower and higher charges respectively.

  35. Examples of Older Names of Cations formed from Transition Metals(you do not have to memorize these)

  36. Learning Check Complete the names of the following binary compounds with variable metal ions: FeBr2 CuCl SnBr4 Fe2O3 Hg2S

  37. Writing Formulas for Ionic Compounds from Names Formulas of ionic compounds are determined from the charges on the ions Na + F Na++ F- NaF Sodium atom + fluorine atom sodium fluoride Charge balance: 1+ + 1- = 0 Remember that all ionic compounds have no net charge, and that the charges are not written in! Ever. Nope.

  38. Neutral, you say? • Formulas are written to make the compound have a neutral charge overall. • You do NOT write the charges in the formula because they MUST cross out to accurately represent the compound. • Ex: NaF2 is INCORRECT for sodium chloride because Na has an oxidation state of +1, and F of -1. There is a one to one ratio of Na+ to F- to make a neutral ionic compound.

  39. Writing the formula… Write the formula for the barium chloride, the compound that will form between Ba2+ and Cl-. Solution: 1. Write the cation, and then the anion 2. Balance charge with the number of + and – ions 3. Write the number of ions needed as subscripts: Ba++ Cl- Think: Cl- Why is Clwritten twice? BaCl2

  40. So what if the oxidation numbers aren’t even? • If the oxidation numbers or charges do not balance, you can write the number of ions of each until you get the same number of each charge in total. • Yes. The “Criss Cross” method. You take the charge number from the cation, and you make it the number of anions, and take the charge on the anion, and you make that many cations. Is there an easier way?

  41. Criss-Crossing in action: Example: Lead (II) nitrate Pb2+ N3- *the charges do not balance Pb2+ N3- Pb3N2 • The 2 and the 3 are brought down to the opposite element, so that there are now 3 Pb2+ ions and 2 N3- ions • This means there were 6e- transferred from the lead atoms to the nitrogen atoms; the compound is neutral

  42. Learning Check Write the correct formula for the compounds containing the following ions: 1. Na+ and S2- a) NaS b) Na2S c) NaS2 2. Al3+ and Cl- a) AlCl3 b) AlCl c) Al3Cl 3. Mg2+ and N3- a) MgN b) Mg2N3 c) Mg3N2

  43. Ternary Ionic Compounds: • Contain at least 3 elements • There MUST be at least one polyatomic ion (it helps to circle the ions) Examples: NaNO3 Sodium nitrate K2SO4 Potassium sulfate Al(HCO3)3 Aluminum bicarbonate (Aluminum hydrogen carbonate)

  44. Specifics for ternary ionic compounds Examples: NaNO3, and Co(NO3)2 • Name the cation first, then polyatomic ion • For NaNO3, the monatomic cation is Na+ , sodium, and the polyatomic anion is NO3- , named nitrate. • NaNO3 is sodium nitrate • For Co(NO3)2, the monatomic cation is Co+2, cobalt (II) and the polyatomic anion is NO3- , named nitrate. • Co(NO3)2 is cobalt (II) nitrate

  45. Learning Check Match each set with the correct name: 1.Na2CO3 a) magnesium sulfite MgSO3 b) magnesium sulfate MgSO4 c) sodium carbonate 2 . Ca(HCO3)2 a) calcium carbonate CaCO3 b) calcium phosphate Ca3(PO4)2 c) calcium bicarbonate

  46. Writing Formulas for Ternary Ionic Compounds • Write the cation first, then the anion. • Overall charge must equal zero. • If charges cancel, just write symbols. • If not, use subscripts to balance charges. • Use parentheses to show more than one of a particular polyatomic ion. • Use Roman numerals indicate the ion’s charge when needed (transition metals) • Remember that the final formula should not have charges written in.

  47. Writing Formulas with Polyatomic Ions Example: Cr2+ PO43- *the charges do not balance Cr2+ PO43- Cr3(PO4)2 The polyatomic ions is in parentheses whenever a subscript is added This is so that we know to count a number of those groups!

  48. Learning Check 1. aluminum nitrate a) AlNO3 b) Al(NO)3 c) Al(NO3)3 2. copper(II) nitrate a) CuNO3 b) Cu(NO3)2 c) Cu2(NO3) 3. Iron (III) hydroxide a) FeOH b) Fe3OH c) Fe(OH)3 4. Tin(IV) hydroxide a) Sn(OH)4 b) Sn(OH)2 c) Sn4(OH)

  49. Ternary Ionic Nomenclature: You Criss-cross these, too. Sodium Sulfate Iron (III) hydroxide Ammonium carbonate

  50. Ternary Ionic Nomenclature: You Criss-cross these, too. Sodium Sulfate Na+ and SO4-2 Na2SO4 Iron (III) hydroxide Fe+3 and OH- Fe(OH)3 Ammonium carbonate NH4+ and CO3–2 (NH4)2CO3

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