14Writing Ion SymbolsWrite the symbol of the element and show the ion charge as a superscriptExample: the symbol of a calcium ion is Ca2+When an ion has a charge of 1+ or 1- the symbol has no number in the superscript, such as Na+ or F-
15Naming Univalent Cations When an element can form only one type of ion, the ion has the same name as the elementEg: Ca2+ = calcium ionCa20p20n+2
16Naming Multivalent Cations A multivalent element is an element that can form an ion in more than one wayExample: An atom of copper can form two different ions: Cu+ or Cu2+
17Naming Multivalent Cations The name of an ion of a multivalent element always contains a Roman numeral that indicates the ion chargeI = 1II = 2III = 3IV = 4V = 5VI = 6
18Naming Multivalent Cations For example, Cu+ is named copper(I) (read as “copper one”)Cu2+ is named copper(II) (read as “copper two”)Only multivalent metals have Roman numerals in their names
19Naming AnionsA nonmetal that has gained electrons to become an ion has the the same name as the element but with the ending changed to -ideEg: Cl- = chloride ion
25Cation ReactivityLiReactivity generally increases for cations as you move down the periodic table.But why?NaElectrons that are further away from the nucleus are more easily lost.Thus atoms with more orbitals will be more reactive.K
26Anion ReactivityReactivity generally decreases for anions as you move down the periodic tableExample: fluorine is more reactive than chlorineIodineBromineAstatineFluorineChlorine
28Anion ReactivityReactivity generally decreases for anions as you move down the periodic tableBut why?FElements whose valence shell is closer to the nucleus will gain electrons more readily because they are closer to the nucleus.Negative electrons have a stronger attraction for the positive nucleus when the valence shell is closer to the nucleus.Cl
29A metal atom that has lost electrons (cation) and a nonmetal atom that has gained electrons (anion) will have the same number of electrons as its nearest noble gas.
30CationsAn metal atom that has lost electrons (cation) will have the same number of electrons as its nearest noble gas.
31CationsFor example, neon is the closest noble gas in the periodic table to sodium, magnesium and aluminum
32CationsThe cations Na+, Mg2+, and Al3+ all have the same number of electrons as atoms of neon.This relationship is known as being isoelectronic (having the same number of electrons).Na11p12n+1Al13p14n+3Mg12p+2Ne10p10n
33Anions Apply concept to anions For example, neon is the closest noble gas in the periodic table to nitrogen, oxygen and fluorine
34IsoelectronicProve that these atoms are isoelectronic by drawing the Bohr diagrams.NeN3-O2-F-
35Ionic CompoundsIn general, an ionic compound consists of a metal and nonmetalIt is more accurate to say that ionic compounds form when atoms of different elements transfer electrons resulting in ions of opposite charges.Thus there is always an electron donor and acceptor.
36Ionic CompoundFor example, this process occurs when atoms of sodium metal (Na) combine with atoms of chlorine (Cl) to form sodium chloride (NaCl), or table salt+=Na Cl NaCl
37Ionic CompoundDuring the formation of NaCl, one electron is transferred from a sodium atom to a chlorine atom
38Ionic CompoundIn general, a cation will react with an anion to acquire a full valence shell
39Ionic CompoundThe attraction between the cation and the anion is known as an ionic bond. This bond is what holds the ionic compound together.
40Properties of Ionic Compound At room temperature, most are hard, brittle solids that can be crushed
41Properties of Ionic Compound Ionic compounds form crystals that have an alternating arrangement of positively charged ions and negatively charged ions, so that when they break their edges are well-defined
42Properties of Ionic Compound In an ionic crystal, every ion is attracted to every other ion in the crystal. As a result, ionic crystals have very high melting pointsex.) NaCl melts at 800oC
43Properties of Ionic Compound When an ionic compound dissolves in water, the crystal structure breaks down and the ions become free to move.
44Properties of Ionic Compound Solutions of ionic compounds can conduct electricity
45Naming Univalent Ionic Compounds Univalent Ionic Compounds are compounds where the metal ion only has one possible charge.
46Naming Univalent Ionic Compounds Name the metal ion firstThe name of the metal ion is the same as the element nameExample: in KBr, the name of the K+ ion is potassiumName the non-metal ion secondWhen a non-metal becomes a negative ion, the ending of its name changes to “ide”Example: a bromine atom become bromide ion (Br -)The formulas of ionic compounds often contain numbers called subscripts which can be ignored when determining the name.Example: Na3P is sodium phosphide
47Naming Univalent Ionic Compounds Example Problem 1:Write the name of the ionic compound ZnF2Name the metal ion:Zn forms only one type of ion (Zn2+), so the name is zincName the non-metal ion:The atom is fluorine so the ion is fluorideCombine the names:ZnF2 = zinc fluoride
48Naming Multivalent Ionic Compounds Multivalent Ionic Compounds are compounds where the metal ion only has two or more possible charges.
49Naming Multivalent Ionic Compounds Identify all the possible charges of the ions.Example: FeOFe can be Fe2+ or Fe3+O is O2-Determine which charge on the multivalent ion is needed to make the compound neutralExample: Need to use Fe2+ to balance O2-
50RULE:Although ionic compounds are made of charged particles, the compound itself has no net chargeAll ion charges of an ionic compound must add up to zeroThe positive and negative charges in an ionic compound must be equal
51Naming Multivalent Ionic Compounds Identify all the possible charges of the ions.Example: FeOFe can be Fe2+ or Fe3+O is O2-Determine which charge on the multivalent ion is needed to make the compound neutralExample: Need to use Fe2+ to balance O2-Name the metal ion indicating the charge in brackets using Roman numerals1 = I, 2 = II, 3 = III, 4 = IV, 5 = VName the non-metal ion changing the ending to ‘ide’Example: FeO = Iron (II) oxide
52Naming Multivalent Ionic Compounds Example Problem 2:Write the name of the ionic compound MnCl4Identify the ions that form the compound: Mn2+ or Mn4+ and Cl-Determine the charge of the multivalent ion that would make the compound neutral.Cl4 means there are 4 x Cl- = a total charge of 4-Would need to use Mn4+Name the metal ion indicating the charge using Roman numerals in brackets and adding the nonmetal –ide.Manganese (IV) iodide
53Polyatomic Ions Poly = 2 or more Atomic = atoms A polyatomic ion is a group of atoms, usually of different elements, that act as a single ionExample: one atom of sulphur and four atoms of oxygen form the polyatomic ion called sulphate, or SO42-
54Polyatomic IonsSimilar polyatomic ions are named using the suffixes “-ate” or “-ite”Example: NO3- is nitrate; NO2- is nitriteMost common polyatomic ions have a negative chargeHowever, the ammonium ion NH4+ has a positive charge
55Polyatomic Ions Name Formula ammonium NH4+ carbonate CO32- bicarbonate HCO3-hydroxideOH-nitrateNO3-nitriteNO2-permanganateMnO4-phosphatePO43-phosphitePO33-sulphateSO42-sulphiteSO32-
56Naming Polyatomic Ionic Compounds Example Problem 3:Write the name of the ionic compound LiHCO3Name the metal/positive ion:Example: Li+ = lithiumIdentify the polyatomic ion (use table):Example: HCO3- = hydrogen carbonateCombine the names. Do not change the polyatomic ending.LiHCO3 = lithium hydrogen carbonate
57Writing Chemical Formula for Uni & Multivalent Ionic Compounds Identify the charge of the ions in the compoundExample: Calcium chlorideCa2+ and Cl-Determine the number of positive and negative ions needed to make the compound neutralNeed 2 Cl- to balance 1 Ca2+Write the metal atom first. Use subscript to indicate the number of ions if it is more than 1. Make sure to use on the lowest common multiple.Calcium chloride = CaCl2Wrong: Ca2Cl4
58Writing Chemical Formula for Uni & Multivalent Ionic Compounds Example Problem 4:Write the chemical formula for Bismuth (V) Phosphide.Bi5+ and P3-How many of each do we need to make the compound neutral?Write the chemical formula using subscripts as needed.
59Writing Chemical Formula for Polyatomic Ionic Compounds Identify the charge of the ions in the compoundExample: Calcium chlorateCa2+ and ClO4-Determine the number of positive and negative ions needed to make the compound neutralNeed 2 ClO4- to balance 1 Ca2+Write the metal atom first. If subscripts are needed for the polyatomic ion, place a bracket around it first. Make sure to use on the lowest common multiple.Calcium chlorate = Ca(ClO4)2
60Writing Chemical Formula for Polyatomic Ionic Compounds Example Problem 5:Write the chemical formula for arsenic (III) acetate.As3+ and C2H3O2-How many of each do we need to make the compound neutral?Write the chemical formula using subscripts and brackets as needed.