Ionic and Metallic Bonding

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Ionic and Metallic Bonding
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Concepts to Master

• Understand the difference between an element and
  a compound.
• Understand ionic bonding and the properties of
  ionic compounds
• Realize the differences between the ionic bonding
  and metallic bonding.
• Write chemical formulas for ionic compounds using
  oxidation number.
• Learn the polyatomic ions.
• Use polyatomic ions when writing chemical
  formulas.
• Learn two methods for balancing chemical
  formulas stacking and criss-cross.
• Understand how and why Lewis dot diagrams work
  for ionic compounds.
• Compare and contrast the Lewis dot diagrams for
  atoms and ions.
• Learn the definition of exothermic and
  endothermic.
• Apply the above definitions to chemical bonding

• Learn how ions and conductivity are related.
• How does ionization energy relate to bond
  formation?
• How are ions in a compound held together?
• How many atoms are in a binary compound?
• How many atoms are in a ternary compound?
• If a compound is ternary, what type of ion does
  it usually contain?
• Be able to calculate formula mass.
• Be able to calculate percent hydration when given
  experimental data or the chemical formula.
• Be able to calculate percent composition when
  given experimental data or the chemical formula.
• What is a sea of mobile electrons and in what
  types of substances is it found?

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Vocab

• Alloys
• Anhydrate
• Anion
• Atom
• Binary
• Cation
• Chemical bond
• Chemical properties
• Compound
• Conductivity
• Electrostatic attraction
• Element
• Endothermic
• Exothermic
• Formula mass

• Hydrate
• Ionic
• Ionic Charge
• Ionization energy
• Ions
• Lewis dot structure
• Metallic
• Mobile electrons
• Oxidation number
• Physical properties
• Polyatomic ion
• Ternary
• Labs
• Exo / Endo Rxns
• Percent Hydration
• Determining oxidation number

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Review Elements versus Compounds

• Atoms are the smallest particle of an element
  that can exist.
• Elements are substances that cannot be separated
  into simpler substances.
• A compound is a substance formed when two or more
  elements are chemically joined. Like atoms, they
  are NEUTRAL.

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Compounds

• The smallest unit of a substance that can exist
  alone and still retain the properties of that
  substance.
• These properties are different than the
  properties of the atoms alone.
• Atoms are Chemically Bonded and can only be
  separated by a chemical process.

Properties of Mg?
Properties of Cl?
Properties of MgCl?
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What is a Chemical Bond?

• A chemical bond is an attraction between atoms
  brought about by a sharing of electrons between
  two atoms or a complete transfer of electrons.
• Bonding occurs so atoms can satisfy the octet
  rule.
• There are three types of chemical bonds
• Ionic
• Covalent
• Metallic 

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Forming Bonds is Exothermic
When the atoms form a bond they become lower in
energy and the system is more stable. The energy
saved by moving to a more stable situation is
released as heat. The more energy released the
greater the compounds stability.
Breaking Bonds is Endothermic
Since atoms form bonds to become more stable,
energy is required to break them apart. When more
energy is required to break the bond, the more
stable the bond is.
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Chemical Equations

• Bond Formation exothermic
• Breaking of Bond endothermic

2 KClO3 --gt  2 KCl 3 O2
Exo or Endo ?
Exo or Endo ?
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Once bonds are formed
Formula Composition
NaCl Total of atoms ____ Total of 2 elements in each compound. 1 sodium and 1 chlorine
NH4OH Total of atoms ____ Total of 3 elements in each compound. 1 oxygen, 5 hydrogen, and 1 nitrogen
KSCN Total of atoms ____ Total of 4 elements in each compound. 1 potassium, 1 sulfur, 1 carbon, 1 nitrogen

• compounds are made.
• and they are written as chemical formulas
• represent the composition of a compound
• group of elemental symbols
• possibly subscript numbers

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• When metallic atoms react
• They lose electrons to form cations.
• They acquire an electron configuration that
  satisfies the octet rule.
• Their radii decrease.
• They want to give electrons away so
  electronegativity is low.

• When non-metal atoms react
• They gain electrons to form anions.
• They acquire an electron configuration that
  satisfies the octet rule.
• Their radii increase.
• They want electrons so electronegativity is high.

Which color is the cation?
Which color is the cation?
Which color is the anion?
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When Metals lose electrons, they get smaller!
When Nonmetals gain electrons, they get bigger!
Cation is
Anion is -
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Ionic Compounds

• Complete TRANSFER of electrons from METAL to
  NONMETAL.
• Metal loses electron to become cation.
• NonMetal gains electron to become anion.
• An electrostatic attraction occurs between the
  cation and anion. (Opposites attract.)
• Properties (Physical or Chemical?)
• Crystals / salts have a lattice formation with
  repeating pattern
• Very hard solids
• Not malleable (brittle), shatters
• Easily dissolve in water
• Conduct electricity when dissolved in water and
  when molten
• Do not conduct electricity as solids
• High melting point What does this tell you about
  chemical bond energy?

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Ionic Compounds
ZnS
CsCl
Are they solid, liquid, or gas? How do you know?
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Na and Cl
Na (Metal) Cl (non-Metal)
Electron configuration is?
of valence electrons?
How many will be lost or gained to achieve an octet?
Lewis Dot Diagram
Lewis Dot Formula
Compound Formula
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Ca and Cl
Ca (Metal) Cl (non-Metal)
Electron configuration is?
of valence electrons?
How many will be lost or gained to achieve an octet?
Lewis Dot Diagram
Lewis Dot Formula
Compound Formula
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Al and O
Al (Metal) O (non-Metal)
Electron configuration is?
of valence electrons?
How many will be lost or gained to achieve an octet?
Lewis Dot Diagram
Lewis Dot Formula
Compound Formula
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Lewis Dot Diagram for Ionic Compounds

• Brackets required
• Each bracket must show charge
• Metallic brackets will have no electron dots
• Non-metallic brackets will show 8 electrons dots
• Stack the positive and negative brackets
• Examples

K3P
AlCl3
NaI
CaF2
Na2S
RbBr
K3P
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Using oxidation numbers to determine compound
formulas

• Oxidation numbers are used to determine the ratio
  in which elements combine to form compounds.
• Cations
• Metals
• Anions
• -
• Non-metals
• Chemical formulas are composed of a positive half
  and a negative half.
• Sodium Chloride is a compound you know to have a
  formula of NaCl.
• The element with the positive oxidation number is
  always written first Na
• The element with the negative oxidation number is
  always written second Cl
• The total of the oxidation numbers in a compound
  must equal zero.
• Na oxidation number is 1 and Cl is -1.
• With one Na and one Cl, the total is 0.

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Steps

• What is the formula of Calcium Nitride?
• Identify the symbols of each part of the name.
• Calcium symbol is Ca.
• Nitride symbol is N.
• Identify the charge for each.
• Calcium is 2.
• Nitride is -3.
• Balance the charges.-Criss-cross method
• Write the symbol beginning with the symbol that
  is first in the name and include the subscript
  after each symbol Ca3N2.
• Check to be sure that the subscript numbers are
  reduced.

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Binary compounds

• Contain only 2 elements
• Write formulas for the following
• Potassium and sulfur
• Rubidium and sulfur
• Magnesium and chlorine
• Sodium and nitrogen

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Binary Cmpds with Roman Numerals

• Many of the transition metals have more than 1
  oxidation number.
• The name of the compound contains a roman numeral
  to indicate which oxidation number was used to
  determine the compound formula.
• Examples

• Copper (II) sulfide
• Mercury (II) iodide

• Iron (III) oxide
• Tin (IV) fluoride

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Polyatomic Ions

• Polyatomic ions are charged group of atoms.
• Contain BOTH ionic and covalent bonds
• Act as a single unit.
• Use parentheses when more than one is present in
  the compound formula.
• Use Table E on the reference booklet.

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Ternary Compounds

• Contain 3 or more different elements
• Often a polyatomic ion is present.
• Na2CO3
• KClO3
• LiOH
• CuSO4
• Writing Formulas for Ternary Compounds

Potassium oxalate
Calcium phosphate

• Ammonium hydroxide

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Conductivity and IONS

• Conductivity is the ability of a material to
  conduct electric current.
• Ions are charged atoms so they conduct
  electricity when dissolved in water.
• Conductivity is proportional to the number of
  ions in solution.
• Increasing the number of ions in a solution
  increases the solutions conductivity.

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Conductivity and IONS
Ionic Compound of Cations of Anions Total of IONS
KCl
Al2(SO4)3
MgBr2
AgOH
Which one will have the GREATEST Conductivity?
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Naming Ions

• Metals name of metal ion.
• Transition Metals name of metal (charge of
  metal) ion.
• Non-metals root of non-metal -ide.
• Polyatomic ions name on Reference Table E

• Examples1. Cu2. Mg23. F-4. OH-5. Fe3
• Answers1. Copper (I) ion 2. Magnesium ion 3.
  Fluoride ion 4. hydroxide ion 5. iron (III) ion

• Hints that you have a polyatomic ion
• 3 or more capital letters in the compound
  (ternary)
• Parenthesis are present
• Compounds name ends in ate or ite.
  Exceptions are hydroxide, peroxide, and cyanide

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Naming Compounds

1. Name the positive part (this always comes first).
   
2. If the positive part is a monatomic cation (a
   single symbol positive ion) - name the element.
3. If the positive part is a polyatomic ion (Table
   E) - name it.
4. Name the negative part (this is the last part of
   the compound).
5. If the negative part is a monatomic anion (a
   single symbol negative ion) - take the root of
   the element and add "ide."
6. If the negative part is a polyatomic ion (Table
   E) - name it.
7. Check to see if a Roman Numeral is needed
8. A Roman numeral is not needed if the positive
   part has only one positive oxidation state on the
   periodic table. (With only one positive oxidation
   state, there is only one possible combination of
   how the elements will bond together.)
9. A Roman numeral is needed if the positive part
   has two or more positive oxidation states on the
   periodic table. (With more than one positive
   oxidation state, there are as many combinations
   of how the elements will bond together as there
   are positive oxidation states.)
10. A Roman Numeral is the value of the Positive
    Oxidation State on one cation.
11. It is not a subscript.
12. It is not the total positive charge.

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Practice Naming

• Ga2(SO3)3
• Ba(OH)2
• Li3N

• Al2(CO3)3
• FeF3
• NH4Cl

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In the old days

• Metals
• "ous" is added to the root of the element for the
  smaller oxidation state.
• "ic" is added to the root of the element for the
  larger oxidation state.
• Examples
• Copper
• Cuprous Cu1
• Cupric Cu2
• Iron
• Fenous Fe2
• Ferric Fe3

Cupric Bromide CuBr2
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Formula Mass

• The formula mass is the total mass of all the
  atoms within the formula.
• When a formula contains polyatomic ions, the
  number of atoms inside the brackets are
  multiplied by any subscript immediately behind
  the brackets.

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Determine the Formula Mass for each of the
following.
KBr LiOH NaNO3
Ba(OH)2 (NH4)2O CaCO3
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Hydrate vs Anhydrate

• Hydrates contain water.
• Water is associated with the chemical.
• The water is not chemically bound because it can
  be removed by simply heating.
• Anhydrates contain NO water. They are dehydrated.

MgBr2 6 H2O(s)  HEAT ? MgBr2 (s) 6
H2O(g)        Hydrate  Anhydrate
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Hydrated Formula Mass

• Sometimes when ionic crystals form, water becomes
  a part of the crystal structure.
• water of hydration
• the crystals are called "hydrates" or "hydrated
  salts
• Formulas for hydrates always include a dot
  separator, followed by the number of water
  molecules attached,
• CuSO4?5H2O
• FeCl2?4H2O

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Hydration - Experimental

• When a 1.000 g sample of CuSO4 5 H2O(s) was
  heated so that the waters of hydration were
  driven off, the mass of the anhydrous salt
  remaining was found to be 0.6390 g. What is the
  experimental value of the percent water of
  hydration?
•  
• CuSO4 5 H2O(s)  HEAT ? CuSO4 (s) 5 H2O (g)
• 1.000 g 0.6390 g
•  
• Find the difference between the mass of hydrate
  before heating and the mass of the anhydrate
  after heating. The difference is the mass of
  water lost.
• 1.000 g - 0.6390 g 0.3610 g
•  
• 2. Dividing the mass of the water lost by the
  mass of hydrate used is equal to the fraction of
  water in the compound. Multiplying this fraction
  by 100 gives the percent water in the hydrate.
• (0.3610 g /1.000 g)(100) 36.10

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Hydration Chemical Formula

• The theoretical (actual) percent hydration
  (percent water) can be calculated from the
  formula of the hydrate by dividing the mass of
  water in one unit of the hydrate by the total
  mass of the hydrate and multiplying this fraction
  by 100.
•  
• What is the percent water in copper(II) sulfate
  pentahydrate, CuSO4 5 H2O?
•  
• Calculate the formula mass.
• 2. Divide the mass of water in one unit of the
  hydrate by the total mass of the hydrate and
  multiply this fraction by 100.
• Percent hydration (90.10 g /249.72 g)(100)
  36.08

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Determine the hydration of

• Na2SO410H2O
• CaCl26H2O

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Composition

• The composition of each element is the mass of
  that element (ionic or covalent) divided by the
  total mass of the compound multiplied by 100.
• What is the composition of sulfur in sodium
  sulfide?
• Determine formula mass.
• Divide formula mass by the mass of sulfur and
  multiply by 100.
• (32.07 / 78.05) x 100 41.09 sulfur

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Determine Composition of the underlined element
Determine Composition of each element

• CaCO3
• KBr

• Sn3P4
• AcF3

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Metallic Bonding

• The electrons can move freely within these
  molecular orbitals, and so each electron becomes
  detached from its parent atom.
• The metal is held together by the strong forces
  of attraction between the positive nuclei and the
  delocalized electrons.
• This is sometimes described as "an array of
  positive ions in a sea of mobile electrons".
• Is a metal made up of atoms or ions? It is made
  of atoms.
• Each positive center in the diagram represents
  all the rest of the atom apart from the outer
  electron, but that electron hasn't been lost - it
  may no longer have an attachment to a particular
  atom, but it's still there in the structure.
  Sodium metal is therefore written as Na (not
  Na).

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Metallic Bonds

• Positive ions immersed in a sea of electrons
• Low ionization energies cause electrons to be
  loosely held
• So valence electrons move among the atoms and
  around the many kernels
• Mobile sea of electrons
• Properties
• Good conductors of electricity and heat as a
  solid or liquid
• Moderately to very hard (Au vs Zr)
• Lustrous since electrons absorb and emit light as
  they move around
• Malleable (not brittle)
• High melting point

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Metallic Bonds
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Alloys

• Material that contains more than one element and
  has the characteristic properties of metals

• Brass
• 67 Cu
• 33 Zn
• Stainless Steel
• 80.6 Fe
• 0.4 C
• 18 Cr
• 1 Ni
• Gold (14K)
• 58 Au
• 42 Cu
• Sterling Silver
• 92.5 Ag
• 7.5 Cu
• Bronze
• 88 Cu
• 12 Sn

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Check

• Draw the Lewis Dot diagrams for aluminum bromide
• Al3 Br-1
• Criss cross AlBr3
• Al 3 Br -1
• Br -1 DOTS?
• Br -1

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check

• Name BaH2
• barium hydride
• Name Mn2(CrO4)3
• Manganese (III) chromate

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check

• Determine the composition for all of the
  elements in barium hydroxide using its chemical
  formula.
• Ba(OH)2
• FW 137.332(1)2(16) 171.33
• Ba (137.33/171.33)x100 80.2
• O (32/171.33)x100 18.7
• H (2/171.33) x100 1.1