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Ions. Ions : A charged particle formed when a neutral atom or group of atoms gain or lose one or more electrons. Example Na  Na + + e - F + e -  F -. Cations. Mg  Mg 2+ + 2e - Al  Al 3+ + 3e - Cation: A positively-charged ion. One or more electrons are lost from a neutral atom

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slide1
Ions

Ions: A charged particle formed when a neutral atom or group of atoms gain or lose one or more electrons.

Example

Na  Na+ + e-

F + e- F-

cations
Cations

Mg  Mg2+ + 2e-

Al  Al3+ + 3e-

Cation: A positively-charged ion. One or more electrons are lost from a neutral atom

 oxidation

anions
Anions

I + e- I-

O + 2e- O2-

S + 2e- S2-

Anion: A negatively-charged ion. Electrons are gained by a neutral atom

 reduction

slide4
Ions
  • Ion charges can be predicted from the Periodic Table
    • Main Group metal (IA-IVA) ion-charges correspond to group number
      • Sodium (Na) in IA  +1
      • Exceptions
        • Tl, Sn, Pb, Sb, and Bi
      • We’ll talk about non-main group metal ion-charges later
    • Main Group non-metal (IIIA-VIIIA) ion-charges correspond to (group# - 8)
      • Fluorine (F) in VIIA  (7-8) = -1
      • Boron is exception  -3 not -5
  • All this has to do with electron configuration
    • More anon
  • See website as well: http://web.clark.edu/aaliabadi/CHEM131ions%20to%20memorize.htm
compounds that contain ions
Compounds That Contain Ions
  • Require metal and non-metal
  • Form ionic bonds
  • Called an ionic compound

Characteristic Properties

1. Very high melting points

2. Conduct an electric current when melted or when dissolved in water

ionic compound
Ionic compound
  • The number of cations and anions must have a net charge of zero.
compounds that contain ions7
Compounds that Contain Ions

Writing Formulas for Ionic Compounds

Give the formulas for the compounds that contain the following pairs of ions:

(a) K and I

(b) Mg and N

(c) Al and O

types of ionic compounds
Types of Ionic Compounds
  • Type I Compounds: The metal present forms only one type of cation.
  • Examples: the main group metals
  • Type II Compounds: The metal present can form two or more cations that have different charges or oxidation states
    • Oxidation state = ionic charge, if any, on species
  • Examples include Cr2+, Cr3+, Cu+, Cu2+, etc.
naming ionic compounds
Naming Ionic Compounds

1. The cation is always named first and the anion second.

2. The cation takes its name from the name of the element.

3. The anion is named by taking the first part of the element name and adding –ide.

naming ionic compounds10
Name the following Type I compounds

NaCl

RaBr2

Rb2O

AlI3

K3N

Cs4Si

Give the chemical formula for the following Type I compounds

Strontium phosphide

Calcium fluoride

Beryllium carbide

Lithium hydride

Barium sulfide

Magnesium telluride

Naming Ionic Compounds
naming ionic compounds11
Naming Ionic Compounds
  • Type II compounds need to be identified by a Roman numeral  (I), (IV), etc.
  • Represents oxidation state of cation
  • Not how many cations are present in compound!
  • Example: NaCl  sodium (I) chloride is INCORRECT
  • Example: SnCl4 tin (IV) chloride is correct
naming ionic compounds12
Naming Ionic Compounds

Type II Ionic Compounds

FeCl2 and FeCl3

PbO and PbO2

MnS and Mn2S7

a mixed bag
A Mixed Bag
  • PbBr2 and PbBr4
  • Aluminum arsenide
  • FeS and Fe2S3
  • Thallium (III) boride
  • Mercury (II) carbide
  • Na2S
  • CoCl3
  • Cerium (IV) phosphide
  • ScF3
  • Gold (I) selenide
  • Vanadium (V) telluride
naming compounds that contain polyatomic ions
Naming Compounds that Contain Polyatomic Ions

Polyatomic Ion: An ion that contains more than one atom. They are charged entities composed of several atoms bound together.

  • Consult my website for the list that must be memorized:
  • http://web.clark.edu/aaliabadi/CHEM131ions%20to%20memorize.htm
trends
Trends
  • Sulfide, sulfite, sulfate
  • Nitride, nitrite, nitrate
  • Phosphide, phosphite, phosphate
  • Chloride, hypochlorite, chlorite, chlorate, perchlorate
  • Parenthesis required if more than one polyatomic ion present
    • Ca(IO3)2 is correct
    • Ca(I)2 is INCORRECT
naming compounds that contain polyatomic ions16
Naming Compounds that Contain Polyatomic Ions

Name or provide the chemical formula for each of the following compounds:

(a) Ca(OH)2 (e) Co(ClO4)2

(b) Sodium phosphate (f) platinum (IV) bicarbonate

(c) KMnO4 (g) Cu(NO2)2

(d) Ammonium dichromate (h) nickel (III) oxalate

naming compounds that contain polyatomic ions17
Naming Compounds that Contain Polyatomic Ions
  • Name or provide each of the following compounds:

(a) calcium carbonate (e) MoO

(b) BaSO4 (f) Iridium (VII) acetate

(c) CsClO4 (g) ZnHPO4

(d) Zirconium bisulfite (h) lithium cyanide

naming acids
Naming Acids

Acids: A substance that yields hydrogen ions (protons, H+) when dissolved in water.

  • HCl(aq)  H+(aq) + Cl-(aq)
  • H3PO4(aq)  3H+(aq) + PO43-(aq)
rules for naming acids
Rules for naming acids
  • If the formula does not contain oxygen the prefix of the acid is hydro and the suffix –ic is attached to the root name for the element.
  • Ex: HCl = hydrochloric acid, H2S = hydrosulfuric acid
  • When the anion contains oxygen, the acid name is formed from the anion name. The suffix –ic or –ous is added.
    • When the anion ends in –ate, the suffix –ic is used.
      • H2CO3 = carbonic acid
    • When the anion ends in –ite, the suffix –ous is used.
      • H2SO3 = sulfurous acid
slide20
More

AnionAcid

ClO4- ______________ HClO4 _______________

ClO3- ______________ HClO3 _______________

ClO2- ______________ HClO2 _______________

ClO- _______________ HClO ________________

naming compounds that contain only nonmetals type iii
Naming Compounds that Contain Only Nonmetals: Type III
  • Type III compounds contain only nonmetals.
  • Form covalent bonds
  •  share electrons

Rules for Naming Type III Binary Compounds

1. The first element in the formula is named first, and the full element name is used.

2. The second element is named as though it were an anion.

3. Prefixes are used to denote the numbers of atoms present.

4. The prefix mono- is never used for naming the first element.

5. Drop the “a” when it is followed by an “o”

 Tetraoxide should be tetroxide

naming compounds that contain only nonmetals type iii22
Naming Compounds that Contain Only Nonmetals: Type III

Prefixes Used to Indicate Numbers in Chemical Names

PrefixNumber Indicated

mono- 1

di- 2

tri- 3

tetra- 4

penta- 5

hexa- 6

hepta- 7

octa- 8

nona- 9

deca- 10

practice
Practice
  • CCl4
  • Silicon dioxide
  • NO2
  • Sulfur trioxide
  • P2O5
  • Iodine pentafluoride
  • Dinitrogen tetroxide
  • SeI2
  • Xenon hexafluoride
the name game
The Name Game
  • Extra credit opportunity
  • Mix-and-match
slide25

Remember the mole?

  • Mole = amt that contains as many “things” as there are atoms of 12 g of C-12
  • 1 mole = 6.022 x 1023 particles
  • Molar mass (MM) = mass in grams per 1 mole of particle (g/mol)
molecular mass
Molecular Mass
  • Summation of molar masses from Periodic Table based on molecular formula
  • NaCl
  • I2
  • V2O5
molar mass
Molar Mass

Example

Calculate the mass of 30.0 moles of polyvinyl chloride (PVC), C2H3Cl.

molar mass28
Molar Mass

Example

A sample of Na2SO4.with a mass of 300.0 grams represents what number of moles of Na2SO4?

Example

Calculate the number of grams of caffeine, C8H10N4O2, in 8.13 x 1023 molecules.

percent composition of compounds
Percent Compositionof Compounds

Example

Compute the mass percent of each element in sodium sulfide, Na2S.

Example

Compute the mass percent of each element in nitric acid, HNO3(aq).

empirical formulas
Empirical Formulas

Empirical Formula: or the simplest formula; the smallest

whole-number ratio of the atoms present.

Molecular Formula: the actual formula of a compound. It gives

the composition of the molecules that are present.

Empirical FormulaMolecular Formula

CH C6H6

CH2O C6H12O6

H2O H2O

calculation of empirical formulas
Calculation of Empirical Formulas

Steps for Determining the Empirical Formula of a Compound

1. Obtain the mass of each element present (in grams).

2. Determine the number of moles of each type of atom present.

3. Divide the number of moles of each element by the smallest number of moles to convert the smallest number to 1. If all of the numbers are integers (whole numbers), these are the subscripts in the empirical formula. If one or more of these numbers are not integers, go to step 4.

4. Multiply the numbers derived in step 3 by the smallest integer that will convert all of them to whole numbers. This set of whole numbers represents the subscripts in the empirical formula.

calculation of empirical formulas33
Calculation of Empirical Formulas

Experiment:

Suppose we weigh out 6.50 grams of Cr. We decide to heat this Cr in the air so that the Cr can react with O to form CrxOy . After the sample cools, we weigh it again and find its mass to be 9.50 grams. How do we find the mass of oxygen?

What is the empirical formula of this compound?

Let’s work on this together.

calculation of empirical formulas34
Calculation of Empirical Formulas

Example

Nylon-6 consists of 63.68% C, 12.38% N, 9.80% H, and 14.14%O.

Calculate the empirical formula for Nylon-6.

calculation of molecular formulas
Calculation of Molecular Formulas

We need to know the empirical formula and molar mass of the molecular compound.

Molecular Formula = (empirical formula)n

where n is a small whole number.

Molecular Formula = n x Empirical Formula

Molar Mass = n x Formula Weight

 n = Molar Mass/Formula Weight

calculation of molecular formulas36
Calculation ofMolecular Formulas

Example

A compound shows the following percentage compostion:

71.65% Cl 24.27% C 4.07% H

The molar mass is known to be 98.96 g/mol. Determine the empirical formula and the molecular formula for this compound.

calculation of molecular formulas37
Calculation ofMolecular Formulas

Example

Vitamin C consists of 40.92% C, 4.58% H, and 54.50% O on a mass basis, and has a molar mass of 176.12 g/mol. Determine the molecular formula of the compound.