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Chapter 3 Ionic Compounds.

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Presentation on theme: "Chapter 3 Ionic Compounds."— Presentation transcript:

1 Chapter 3 Ionic Compounds

2 Bonding The joining of two atoms in a stable arrangement
Elements gain, lose, or share electrons to reach the electron configuration of the noble gas closest to them in the periodic table Two types of bonding Ionic bonds: result from the transfer of electrons from one element to another Covalent bonds: result from the sharing of electrons between two atoms

3 Elements A pure substance that cannot be broken down into simpler substances by a chemical reaction Identified by a one- or two-letter symbol Arranged in the periodic table Its location on the periodic table indicates a lot about its chemical properties Can be a metal, nonmetal, or a metalloid

4 Ionic bonds

5 Ionic bonds Ionic bonds
Form between a metal (left side of periodic table) and a nonmetal (right side of periodic table

6 Periodic Table Covalent bonds Form when two nonmetals combine
Form when a metalloid bonds to a nonmetal

7 Cations Positively charged ions Have fewer elections (e-) than protons
sodium atom sodium ion

8 Anions Negatively charged ions Has more e- than protons
chlorine atom chlorine ion

9 Octet rule octet = 8 valence e−
A main group element is especially stable when it possesses an octet of e- in its outer shell octet = 8 valence e−

10 Charge based on periodic group
the cation charge = the group number group 1A: M 1 valence e− M e− group 2A: M 2 valence e− M e− group 3A: M 3 valence e− M e−

11 Charge based on periodic group
the anion charge = 8 – group number group 6A: X 6 valence e− + 2e− X 2− charge = 8 – 6 = 2 group 7A: X 7 valence e− + e− X − charge = 8 – 7 = 1

12 Main Group Ions

13 Metals with variable charges

14 Biologically relevant ions

15 Ionic compounds The sum of the charges in an ionic compound must be zero overall Ions will arrange to maximize anion-cation attractions and minimize anion-anion and cation-cation repulsions

16 Ion compounds – charge balance
There must be two F- anions for each Ca+ cation to have an overall charge of zero

17 Formula for ionic compounds
HOW TO Write a Formula for an Ionic Compound Identify which element is the cation and which is the anion. Step [1] Determine how many of each ion type is needed for an overall charge of zero. Step [2] When the cation and anion have different charges, use the ion charges to determine the number of ions of each needed. To write the formula, place the cation first and then the anion, and omit charges. Step [3]

18 Example Calcium Iodide Cation = calcium Anion = iodine
Charge 2+ Anion = iodine Charge - Need two iodine for every calcium for an overall charge of zero CaI2

19 Ionic comound criss-cross rule
Make magnitude of charge on one ion into subscript for other When doing this, make sure that subscripts are reduced to lowest whole number. Al3+ O2– Al2O3

20 Main group cations Main group cations are named for the element from
which they are formed. Na+ K+ Ca2+ Mg2+ sodium potassium calcium magnesium

21 Multiple charge cations
Systematic name Follow the name of the cation by a Roman numeral in parentheses to indicate its charge Common name Use suffic “-ous” for the cation with a smaller charge and suffix “-ic” for the cation with a higher charge Fe2+ Fe3+ iron(II) iron(III) Fe2+ Fe3+ ferrous ferric

22 Anions Anions are named by replacing the ending of the element name by the suffix “-ide.”

23 Naming ionic compounds
Name the cation and then the anion Do not specify the charge on the ion Do not specify how many ions of each type are needed to balance charge Na+ sodium + F− fluoride NaF sodium fluoride Mg2+ magnesium + Cl− chloride MgCl2 magnesium chloride

24 HOW TO Name an Ionic Compound
Naming ionc compounds HOW TO Name an Ionic Compound Step [1] Determine the charge on the cation. Step [2] Name the cation and the anion If the cation could be multiple charges indicate the charge with roman numerals or with a –ous / -ic suffix. Write the name of the cation first then the name of the anion Step [3]

25 Examples K2O LiBr SnO Cation = K+ Anion = O2- Potassium Oxide
Cation = Li+ Anion = Br- Lithium Bromide SnO Cation = Sn2+ Tin (II) Oxide /Stannous Oxide

26 Naming ionic compounds
HOW TO Derive the Formula from the Name of an Ionic Compound Step [1] Identify the cation and the anion. Step [2] Determine the charge on the cation and anion. Balance the charges. Step [3] Write the formula with the cation first and use subscripts to communicate charge balance. Step [4]

27 Examples Cobalt (II) Oxide/Cobaltous Oxide
Cation = Co 2+ Anion = O2- CoO Iron(III) Fluoride/Ferric Flouride Cation = Fe3+ Anion = F- FeF3 Beryllium Chloride Cation = Be2+ Anion = Cl- BeCl2

28 Physical properties of ionic compounds
Ionic compounds are crystalline solids with very high melting and boiling points When ionic compounds dissolve in water, they separate into cations and anions, increasing the conductivity of the solution + NaCl water solution

29 Polyatomic ions A cation or anion that contains more than one atom
The multiple atoms are held together with covalent bonds The molecule has an overall charge associated with it

30 Formulas for polyatomic ions
When a cation and anion of equal charge combine, only one of each ion is needed Na+ + NO2− NaNO2 zero overall charge Ba2+ + SO42− BaSO4 zero overall charge

31 Formulas for polyatomic ions
When a cation and anion of unequal charge combine, use the ionic charges to determine the relative number of each ion that is needed Mg2+ + OH− Mg(OH)2 +2 charge means 2 OH− anions are needed. −1 charge means 1 Mg2+ anion is needed. zero overall charge

32 Naming polyatomic ionic compounds
The same rules are followed for naming standard ionic compounds: Name the cation and then the anion. Do not specify the charge on the ions. Do not specify how many ions of each type are needed to balance charge. Use –ite suffix if 1 or less Oxygen atoms in anion Use –ate suffix if more Oxygen atoms in anion Use bi- prefix or write hydrogen if H part of anion NaHCO3 Al2(SO4)3 sodium bicarbonate aluminum sulfate

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