Structure of Matter

1
Chapter 4

• Structure of Matter

2
What are compounds

• When elements combine to form a new substance
  with properties different from those of the
  elements
• The attractive force that holds different atgoms
  together are chemical bonds
• Mixtures are made of different substances that
  are just placed together

3
Compounds

• Always have the same formula
• H2O
• CO2
• You can see how the elements in a compound are
  connected by the chemical structure.
• Bond length gives the distance between the nuclei
  of the bonded atoms
• Bond angles tell how the atoms are positioned

4
Models of Compounds

• Ball and Stick
• Help you see the compounds structure
• Space filling
• Show the space that the atoms of the compound
  occupy

5
Structure vs. Properties

• Network Structure
• Very strong bonds
• Identical bond angles
• solids
• Bonded Ions
• Regularly shaped crystals
• Tightly packed Na and Cl-
• High melting and boiling points
• Molecules
• Little attraction between molecules in the
  network
• Spread out

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Introduction to Chemical Bonding

• OBJECTIVES
• Distinguish between ionic and molecular compounds
• Define cation and anion, and relate them to metal
  and nonmetal

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Atoms and ions

• Atoms are electrically neutral
• Same number of protons and electrons
• Ions are atoms, or groups of atoms, with a charge
  (positive or negative)
• Different numbers of protons and electrons
• Only electrons can move
• Gain or lose electrons

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Anion

• A negative ion
• Has gained electrons
• Nonmetals can gain electrons
• Charge is written as a superscript on the right

Has gained one electron (-ide is new ending
fluoride)
F1-
O2-
Gained two electrons (oxide)
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Cations

• Positive ions
• Formed by losing electrons
• More protons than electrons
• Metals can lose electrons

Has lost one electron (no name change for
positive ions)
K1
Ca2
Has lost two electrons
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Ionic Compounds

• Ionic compounds- from joining metal cations and
  nonmetal anions- they are electrically neutral
• Usually solid crystals
• Melt at high temperatures

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Molecules and Molecular Compounds

• Naming is essential in chemistry
• Molecule- smallest electrically neutral unit,
  still has properties of the substance
• Made from only nonmetals
• Properties of molecular compounds
• Low melting and boiling points
• Usually gas or liquid

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Two Types of Compounds

• Molecular compounds
• Made of molecules
• Made by joining nonmetal atoms together into
  molecules
• Ionic Compounds
• Made of cations and anions
• Metals and nonmetals
• The electrons lost by the cation are gained by
  the anion
• Smallest piece is a FORMULA UNIT

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Two Types of Compounds (cont)
Ionic
Molecular
Smallest piece
Formula Unit
Molecule
Types of elements
Metal and Nonmetal
Nonmetals
Solid, liquid or gas
State
solid
Melting Point
High gt300ºC
Low lt300ºC
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Systematic Naming

• There are too many compounds to remember the
  names of them all
• Compound is made of two or more elements
• Put together atoms
• Name should tell us how many and what type of
  atoms

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Chemical Formulas

• Shows the kind and number of atoms in the
  smallest piece of a substance
• Molecular formula- number and kinds of atoms in a
  molecule
• More than one atom? use a subscript (H2O)
• There are 7 diatomic elements
• H2, N2, O2, F2, Cl2, Br2, and I2

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Ionic Compounds

• This formula represents not a molecule, but a
  formula unit
• The smallest whole number ratio of atoms in an
  ionic compound

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Ionic Charges

• OBJECTIVES
• Use the periodic table to determine the charge on
  an ion
• Define a polyatomic ion, and give the names and
  formulas of the most common polyatomic ions

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Charges on ions

• For most of the Group A elements, the Periodic
  Table can tell what kind of ion they will form
  from their location monatomic ions
• Elements in the same group have similar
  properties
• Including the charge when they are ions

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1
2
3
3-
2-
1-
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What about the others?

• Groups 4A and 0 do not usually form ions (in
  fact, Group 0 rarely forms compounds!)
• Many transition metals have more than one common
  ionic charge

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Naming ions

• If more than one charge is possible
• Stock system uses roman numerals in parenthesis
  to indicate the numerical value
• Cation- if the charge is always the same (Group
  A) just write the name of the metal
• Transition metals can have more than one type of
  charge
• Indicate the charge with roman numerals in
  parenthesis

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Name these

• Na1
• Ca2
• Al3
• Fe3
• Fe2
• Pb2
• Li1

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Write Formulas for these

• Potassium ion
• Magnesium ion
• Copper (II) ion
• Chromium (VI) ion
• Barium ion
• Mercury (II) ion

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Naming Anions

• Anions are always the same charge
• Change the element ending to ide
• F1- Fluorine
• F1- Fluoride

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Name these

• Cl1-
• N3-
• Br1-
• O2-

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Write these

• Sulfide ion
• Iodide ion
• Phosphide ion

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Exceptions

• Some of the transition metals have only one ionic
  charge
• Do not use roman numerals for these
• Silver is always 1 (Ag1)
• Cadmium and Zinc are always 2 (Cd2 and Zn2)

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Polyatomic ions

• Groups of atoms that stay together and have a
  charge
• Acetate C2H3O21-
• Nitrate NO31-
• Nitrite NO21-
• Hydroxide OH1- and Cyanide CN1-
• Permanganate MnO41-

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Polyatomic ions

• Sulfate SO42-
• Sulfite SO32-
• Carbonate CO32-
• Chromate CrO42-
• Dichromate Cr2O72-

• Phosphate PO43-
• Phosphite PO33-
• Ammonium NH41

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Ionic Compounds

• OBJECTIVES
• Apply the rules for naming and writing formulas
  for binary ionic compounds
• Apply the rules for naming and writing formulas
  for ternary ionic compounds

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Naming Binary Ionic Compounds

• Binary Compounds - 2 elements
• Ionic - a cation and an anion
• To write the names, just name the two ions
• Easy with Representative elements (which are
  Group A elements)
• NaCl Na1 Cl1- sodium chloride
• MgBr2 Mg2 Br1- magnesium bromide

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Naming Binary Ionic Compounds

• The problem comes with the transition metals
• Need to figure out their charges
• The compound must be neutral
• Same number of and charges
• Use the anion to determine the charge on the
  positive ion

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Naming Binary Ionic Compounds

• Write the name of CuO
• Need the charge of Cu
• O is 2-
• copper must be 2
• Copper (II) oxide
• Name CoCl3
• Cl is 1- and there are three of them 3-
• Co must be 3 Cobalt (III) chloride

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Naming Binary Ionic Compounds

• Write the name of Cu2S
• Since S is 2-, the Cu2 must be 2, so each one is
  1
• copper (I) sulfide
• Fe2O3
• Each O is 2- 3 x -2 -6
• 2 Fe must 6, so each is 3.
• iron (III) oxide

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Write the names

• KCl
• Na3N
• CrN
• Sc3P2
• PbO
• PbO2
• Na2Se

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Ternary Ionic Compounds

• These will have polyatomic ions
• At least three elements
• Name the ions
• NaNO3
• CaSO4
• CuSO3
• (NH4)2O

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Writing Formulas

• The charges have to add up to zero
• Get charges on pieces
• Cations from name on table
• Anions from table or polyatomic
• Balance the charges by adding subscripts
• Put polyatomics in parenthesis

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Writing Formulas

• Write the formula for calcium chloride
• Calcium is Ca2
• Chloride is Cl1-
• Ca2 Cl1- would have a 1 charge
• Need another Cl1-
• Ca2 Cl21- (use criss-cross method)

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Write the formulas for these

• Lithium sulfide
• Tin (II) oxide
• Tin (IV) oxide
• Magnesium fluoride
• Copper (II) sulfate
• Iron (III) phosphide
• Iron (III) sulfide

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Write the formulas for these

• Ammonium chloride
• Ammonium sulfide
• Barium nitrate

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Things to look for

• If cations have ( ), the number in parenthesis is
  their charge
• If anions end in -ide they are probably off the
  periodic table (Monoatomic)
• If anion ends in -ate or -ite it is polyatomic

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Molecular Compounds and Acids

• OBJECTIVES
• Apply the rules for naming and writing formulas
  for binary molecular compounds
• Name and write formulas for common acids

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Molecular compounds

• Made of just nonmetals
• Smallest piece is a molecule
• Cant use charges to figure out how many of each
  atom
• Molecular compounds name tells you the number of
  atoms
• Uses prefixes to tell you the number

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Prefixes

• 1 mono-
• 2 di-
• 3 tri-
• 4 tetra-
• 5 penta-
• 6 hexa-
• 7 hepta-
• 8 octa-
• 9 nona-
• 10 deca-

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Prefixes

• To write the name, write two words
  
• One exception is we dont write mono- if there is
  only one of the first element
• No double vowels when writing names (oa oo)

Prefix
name
Prefix
name
-ide
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Name These

• N2O
• NO2
• Cl2O7
• CBr4
• CO2
• BaCl2

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Write formulas for these

• diphosphorus pentoxide
• tetraiodine nonoxide
• sulfur hexafluoride
• nitrogen trioxide
• carbon tetrahydride
• phosphorus trifluoride

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Organic Biological Compounds
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Organic Compounds

• All contain carbon
• Some compounds with carbon are not organic
• Carbon monoxide carbon dioxide
• CO CO2
• Carbonates - -CO3
• 90 of all compounds are organic

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Reasons why carbon forms so many compounds

• C can form 4 bonds
• - C -
• 
  
• C can form single, double, or triple bonds (it
  forms many types of bonds)
• C can bond with atoms of many different element

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Hydrocarbons

• Made of only H and C
• Used for fuel and manufacturing processes
• Types
• Saturated have only single bonds
• Unsaturated have double or triple bonds

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Classification of hydrocarbons

• Alkanes single bonds (saturated)
• Alkenes double bond (unsaturated)
• Alkynes triple bond (unsaturated)
• Cycloalkanes carbons are single bonded in a
  ring structure

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Substituted hydrocarbons

• One or more H atoms are replaced by
  other elements
• Alcohols H is replaced by a hydroxyl group
  (-OH)
• Organic acids H is replaced by a carboxyl group
  (-COOH)

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Biological Compounds

• Proteins
• Contain C, H, O, and N
• Polymers of amino acids (about 20 varieties)
• Polymers are long chains of smaller organic
  molecules (monomers)
• Peptide bonds link amino acids
• Proteins make all enzymes (regulate chemical
  reactions in our bodies)

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Nucleic Acids

• DNA (deoxyribonucleic acid)
• RNA (ribonucleic acid)
• Control cellular activities
• Made of smaller units called nucleotides

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Carbohydrates

• Made of C, H, and O (2x as many H as O)
• Types
• Sugars (glucose sucrose)
• Starches (polymers)
• Our main source of energy (food)

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Lipids

• Made of C, H, and O
• Types
• Fats (animals) - saturated
• Oils (plants) unsaturated
• Used for storing energy in living things
• Cholesterol - animals use it to build cell
  membranes

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The End