Nomenclature Slides PDF

H2O “CHEMICAL NAMES AND FORMULAS”  electron shells a) Atomic number = number of Electrons b) Electrons vary in the amount of energy they possess, and they occur at certain energy levels or electron shells. c) Electron shells determine how an atom beha...

H2O “CHEMICAL NAMES AND FORMULAS”  electron shells a) Atomic number = number of Electrons b) Electrons vary in the amount of energy they possess, and they occur at certain energy levels or electron shells. c) Electron shells determine how an atom behaves when it encounters other atoms  Electrons are placed in shells according to rules: 1) The 1st shell can hold up to two electrons, and the next two shells of the elements we will be studying will hold up to 8 electrons. Octet Rule = atoms tend to gain, lose or share electrons so as to have 8 electrons ✔C would like to Gain 4 electrons ✔N would like to Gain 3 electrons ✔O would like to Gain 2 electrons  Why are electrons important? 1) Elements have different electron configurations ▪ different electron configurations mean different levels of bonding 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. An Anion is… A negative ion. Has gained electrons. Nonmetals can gain electrons. Charge is written as a superscript on the right. 1- Has gained one electron (-ide F is new ending = fluoride) 2- Gained two electrons (oxide) O  A Cation is… A positive ion. Formed by losing electrons. More protons than electrons. Metals can lose electrons 1+ Has lost one electron (no K name change for positive ions) 2+ Ca Has lost two electrons  Covalent Bond Between nonmetal elements Formed by sharing electron pairs They are not conductors, but rather good insulators Examples; O2, CO2, C2H6, H2O, SiC - water is a molecule that is covalently bonded. The electrons are SHARED.  Ionic Bond Between atoms of metals and nonmetals with very different electronegativity Bond formed by transfer of electrons Produce charged ions all states. Examples; NaCl, CaCl2, K2O 1). Ionic bond – electron from Na is transferred to Cl, this causes a charge imbalance in each atom. The Na becomes (Na+) and the Cl becomes (Cl-), charged particles or ions.  Formation of Ions from Metals Ionic compounds result when metals react with nonmetals Metals lose electrons to match the number of valence electrons of their nearest noble gas Positive ions form when the number of electrons are less than the number of protons Group 1 metals ⎯→ ion 1+ Group 2 metals ⎯→ ion 2+ Group 13 metals ⎯→ ion 3+  Formation of Sodium Ion Sodium atom Sodium ion Na ∙ – e− ⎯⎯→ Na + 2-8-1 2-8 ( = Ne) 11 p+ 11 p+ 11 e- 10 e- 0 1+  Formation of Magnesium Ion Magnesium atom Magnesium ion ∙ Mg ∙ – 2e− ⎯→ Mg2+ 2-8-2 2-8 (=Ne) 12 p+ 12 p+ 12 e- 10 e- 0 2+  Some Typical Ions with Positive Charges (Cations) Group 1 Group 2 Group 13 H+ Mg2+ Al3+ Li+ Ca2+ Na+ Sr2+ K+ Ba2+  Learning Check A. Number of valence electrons in aluminum 1) 1 e- 2) 2 e- 3) 3 e- B. Change in electrons for octet 1) lose 3e- 2) gain 3 e- 3) gain 5 e- C. Ionic charge of aluminum 1) 3- 2) 5- 3) 3+  Solution A. Number of valence electrons in aluminum 3) 3 e- B. Change in electrons for octet 1) lose 3e- C. Ionic charge of aluminum 3) 3+  Ions from Nonmetal Ions In ionic compounds, nonmetals in 15, 16, and 17 gain electrons from metals Nonmetal add electrons to achieve the octet arrangement Nonmetal ionic charge: 3-, 2-, or 1- 1). Ionic bond – electron from Na is transferred to Cl, this causes a charge imbalance in each atom. The Na becomes (Na+) and the Cl becomes (Cl-), charged particles or ions.  Predicting Ionic Charges Group 1A: Lose 1 electron to form 1+ ions H1+ Li1+ Na1+ K1+ Rb1+  Predicting Ionic Charges Group 2A: Loses 2 electrons to form 2+ ions Be2+ Mg2+ Ca2+ Sr2+ Ba2+ Predicting Ionic Charges 3+ 3+ 3+ Group 3A: Loses 3 B Al Ga electrons to form 3+ ions  Predicting Ionic Charges Neither! Group 4A Group 4A: Do they elements rarely form lose 4 electrons or ions (they tend to share) gain 4 electrons? Predicting Ionic Charges N3- Nitride Group 5A: Gains 3 P3- Phosphide electrons to form As3- Arsenide 3- ions Predicting Ionic Charges O2- Oxide Group 6A: Gains 2 S2- Sulfide electrons to form Se2- Selenide 2- ions  Predicting Ionic Charges 1- 1- Group 7A: Gains F Fluoride Br Bromide 1 electron to form Cl1- Chloride I1- Iodide 1- ions Predicting Ionic Charges Group 8A: Stable noble gases do not form ions!  Predicting Ionic Charges Group B elements: Many transition elements have more than one possible oxidation state. Note the use of Roman Iron (II) = Fe2+ numerals to show charges Iron (III) = Fe3+ Naming cations 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 parentheses after the name of the metal  Predicting Ionic Charges Some of the post-transition elements also have more than one possible oxidation state. Tin (II) = Sn2+ Lead (II) = Pb2+ Tin (IV) = Sn4+ Lead (IV) = Pb 4+  Predicting Ionic Charges Group B elements: Some transition elements have only one possible oxidation state, such as these three: Silver = Ag1+ Zinc = Zn2+ Cadmium = Cd2+  Electron Dot (Lewis Dot) Structures Symbols of atoms with dots to represent the valence-shell electrons 1 2 13 14 15 16 17 18 H∙ He: ∙ ∙ ∙ ∙∙ ∙∙ ∙∙ ∙∙ Li∙ Be∙ ∙ B∙ ∙ C∙ ∙ N∙ ∙ O∙ : F ∙ :Ne : ∙ ∙ ∙∙ ∙∙ ∙∙ ∙ ∙ ∙ ∙∙ ∙∙ ∙∙ ∙∙ Na∙ Mg∙ ∙ Al∙ ∙ Si ∙ ∙ ∙ P ∙ ∙ S :Cl ∙ :Ar : ∙ ∙ ∙∙ ∙∙ ∙∙  Learning Check A. X would be the electron dot formula for 1) Na 2) K 3) Al B. X would be the electron dot formula 1) B 2) N 3) P  Exceptions: Some of the transition metals have only one ionic charge: Do not need to use roman numerals for these: 1+ Silver is always 1+ (Ag )=Ag Cadmium and Zinc are always 2+ 2+ 2+ (Cd and Zn )=Cd & Zn  Naming Ionic Compounds 1. Name the cation first, then anion 2. Monatomic cation = name of the element Ca2+ = calcium ion 3. Monatomic anion = root + -ide − Cl = chloride CaCl2 = calcium chloride Practice by naming these: Na1+ Ca2+ 3+ Al Fe3+ 2+ Fe Pb2+ Li1+ Write symbols for these: Potassium ion Magnesium ion Copper (II) ion Chromium (III) ion Barium ion Mercury (II) ion Naming Anions Anions are always the same charge Change the monatomic element ending to – ide 1- F a Fluorine atom will become a Fluoride ion. Practice by naming these: 1- Cl 3- N 1- Br 2- O Write symbols for these: Sulfide ion Iodide ion Phosphide ion  Writing Ionic Compound Formulas Example: Aluminum sulfide (note the 2 word name) 1. Write the formulas for the 3 2 cation and anion, including CHARGES! Al 2 S 3 2. Check to see if charges Now balanced. are balanced. Not balanced! = Al2S3 3. Balance charges , if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Use the criss-cross method to balance the subscripts.  Writing Ionic Compound Formulas Example: Iron (III) chloride (note the 2 word name) 1. Write the formulas for the 3 1 cation and anion, including Fe Cl CHARGES! 3 Now balanced. 2. Check to see if charges Not balanced! are balanced. = FeCl3 3. Balance charges , if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Use the criss-cross method to balance the subscripts. Naming Ionic Compounds (Metals with multiple oxidation states) some metals can form more than one charge (usually the transition metals) use a Roman numeral in their name: PbCl2 – use the anion to find the charge on the cation (chloride is always 1-) Pb2+ is the lead (II) cation PbCl2 = lead (II) chloride Things to look for: 1) If cations have ( ), the number in parenthesis is their charge. 2) If anions end in -ide they are probably off the periodic table (Monoatomic) 3) If anion ends in -ate or –ite, then it is polyatomic Polyatomic ions are… Groups of atoms that stay together and have an overall charge, and one name. Usually end in –ate or -ite 1- Acetate: C 2H 3O 2 1- Nitrate: NO3 1- Nitrite: NO2 1- Permanganate: MnO4 1- 1- Hydroxide: OH and Cyanide: CN  3- Sulfate: SO4 2- Phosphate: PO4 3- Sulfite: SO 2- Phosphite: PO 3 3 2- Carbonate: CO 3 1+ Ammonium: NH4 (One of the few positive polyatomic ions) If the polyatomic ion begins with H, then combine the word hydrogen with the other polyatomic ion present: H1+ + CO32- → HCO31- hydrogen + carbonate → hydrogen carbonate ion  Writing Polyatomic Compound Formulas Example: Barium nitrate (note the 2 word name) 1. Write the formulas for the 2+ ( -) cation and anion, including CHARGES! Ba NO3 2 2. Check to see if charges are Now balanced. balanced. Not balanced! = Ba(NO3)2 3. Balance charges , if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Use the criss-cross method to balance subscripts.  Writing Polyatomic Compound Formulas Example: Ammonium sulfate (note the 2 word name) 1. Write the formulas for the cation and anion, including ( NH4+) SO42- CHARGES! 2 2. Check to see if charges Now balanced. are balanced. Not balanced! = (NH4)2SO4 3. Balance charges , if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Use the criss-cross method to balance the subscripts.  Writing Polyatomic Compound Formulas Example: Magnesium carbonate (note the 2 word name) 1. Write the formulas for the 2+ 2- cation and anion, including Mg CO3 CHARGES! 2. Check to see if charges They are balanced! are balanced. = MgCO3  Writing Polyatomic Compound Formulas Example: Zinc hydroxide (note the 2 word name) 1. Write the formulas for the cation and anion, including Zn 2+ ( OH- )2 CHARGES! 2. Check to see if charges are Now balanced. balanced. Not balanced! = Zn(OH)2 3. Balance charges , if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Use the criss-cross method to balance the subscripts.  Writing Polyatomic Compound Formulas Example: Aluminum phosphate (note the 2 word name) 1. Write the formulas for the 3+ 3- cation and anion, including CHARGES! Al PO4 2. Check to see if charges are balanced. They ARE balanced! = AlPO4  Practice by writing the formula or name as required… Iron (II) Phosphate Potassium Sulfide MgSO4 FeCl3 Practice by writing the formula for the following: Magnesium hydroxide Iron (III) hydroxide Zinc hydroxide  Covalent Bond Between nonmetal elements Formed by sharing electron pairs They are not conductors, but rather good insulators Examples; O2, CO2, C2H6, H2O, SiC - water is a molecule that is covalently bonded. The electrons are SHARED.  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) 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! Prefixes 1 = mono- 2 = di- 3 = tri- 4 = tetra- 5 = penta- 6 = hexa- 7 = hepta- 8 = octa- Prefixes 9 = nona- 10 = deca- To write the name, write two words: One exception is we don’t write mono if there is only one of the first element. Prefixwename Normally, Prefix do not have double name -ide vowels when writing names (oa oo) Practice by naming these: N O = dinitrogen monoxide 2 (also called nitrous oxide or laughing gas) NO2 = nitrogen dioxide Cl2O7 = dichlorine heptoxide CBr4 = carbon tetrabromide CO2 = carbon dioxide BaCl2 (This one will not use prefixes, since it is an ionic compound!) Molecules and Molecular Compounds Diatomic molecule—a molecule that contains two atoms. = HOFBrINCl Other elements found in nature in the form of diatomic molecules include hydrogen, nitrogen, oxygen, and the halogens. HOFBrINCl Write formulas for these: diphosphorus pentoxide tetraiodine nonoxide sulfur hexafluoride nitrogen trioxide carbon tetrahydride phosphorus trifluoride aluminum chloride (Ionic compound) Helpful to remember... 1. In an ionic compound, the net ionic charge is zero (criss-cross method) 2. An -ide ending generally indicates a binary compound 3. An -ite or -ate ending means there is a polyatomic ion that has oxygen 4. Prefixes generally mean molecular; they show the number of each atom  Helpful to remember... 5. A Roman numeral after the name of a cation is the ionic charge of the cation Acids are… Compounds that give off 1+ hydrogen ions (H ) when dissolved in water Will start the formula with H(there are exceptions) There will always be some Hydrogen next to an anion. The anion determines the name.  Rules for Naming acids: Name it as a normal compound first 1) 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  Naming Acids If the anion has oxygen in it, then it ends in -ate or -ite 2) change the suffix -ate to -ic acid (use no prefix) Example: HNO3 Hydrogen and nitrate ions = Nitric acid 3) change the suffix -ite to -ous acid (use no prefix) Example: HNO2 Hydrogen and nitrite ions = Nitrous acid To write a formula for an acid or base, we will need to balance the charges. Naming Acids Normal ending Acid name is… ____-ide hydro-___-ic acid ____-ate _____-ic acid ____-ite _____-ous acid Practice by naming these: HF H 3P H2SO4 H2SO3 HCN H2CrO4 Writing Acid Formulas – in reverse! Hydrogen will be listed first The name will tell you the anion Be sure the charges cancel out. Starts with prefix hydro?- there is no oxygen, -ide ending for anion no prefix hydro? 1) -ate anion comes from –ic ending 2) -ite anion comes from –ous ending Write formulas for these: acetic acid carbonic acid phosphorous acid hydrobromic acid Names and Formulas for Bases A base is an ionic compound that produces hydroxide ions (OH1-) when dissolved in water Bases are named the same way as other ionic compounds: The name of the cation (which is a metal) is followed by the name of the anion (which will be hydroxide). Names and Formulas for Bases NaOH is sodium hydroxide Ca(OH)2 is calcium hydroxide To write the formula: 1) Write the symbol for the metal cation 2) followed by the formula for the hydroxide ion (OH1-) 3) then use the criss-cross method to balance the charges.