Chapter

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Chapter 5Chemistry for Changing Times

• Chemical Bonds The Ties That Bind

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Chapter 5 Learning Objectives

• How Do Elements Combine to Form Compounds?
• Why Are Chemical Bonds So Important?
• What Are the Different Types of Chemical Bonds?
• Why Are Compounds So Unlike Their Component
  Elements?
• How/Why Do Reacting Atoms Attempt to Attain a
  Stable Electron Configuration?

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Chapter 5 Learning Objectives

• What Are the Exceptions To the Octet Rule?
• How Does the Rule of Eight Apply To Reacting
  Atoms In the Periodic Table?
• How Are Electrons Represented Symbolically In the
  Outer Energy Levels of Atoms?
• How Are Ionic Bonds Formed?

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Chapter 5 Learning Objectives

• How Are the Combination of Simple Ions Noted?
• What Is the Difference Between Ionic and Covalent
  Bonds?
• What Are the Three Types of Covalent Bonds?
• How Do Atoms Enter Into the Unequal Sharing of
  Electrons?

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Chapter 5 Learning Objectives

• What Happens When Two Or More Charged Particles
  Bond?
• How Are Molecular Shapes of Molecules Determined?
• What Are the Rules For Determining the Shapes of
  Molecules?
• How Does the Polarity of a Molecule Affect Its
  Shape?
• What Are the Forces That Determine the Physical
  States of Matter?

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Chapter 5 Learning Objectives

• How Are the Physical States of Matter Determined?
• What Are the Interactions That Hold Solids and
  Liquids Together?
• What Are the Forces Involved in the Formation of
  Solutions?

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How Does Electron Configuration Relate to the
Periodic Table?

• Family features of the periodic table.
• Period groups arranged according to the number of
  atom energy levels.
• Sulphur third group 3 energy levels in the
  atom.
• Group number number of electrons in outer
  energy level valence electrons.
• Sulphur group 6A 6 valence electrons.
• 2 electrons in s orbital and 4 in p orbital.

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How Does Electron Configuration Relate to the
Periodic Table?

• Importance of outermost electrons.
• Determines chemistry of an atom.
• Source of chemical reactions.
• If elements have same number of valence electrons
  in outer orbitals
• They are members of same group in periodic table.
• They have very similar chemical characteristics.

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How Do We Distinguish Between Metals, Nonmetals
and Metalloids?

• Elements in the periodic table are divided by a
  heavy, stair step vertical line.
• Metals left of line.
• Luster.
• Good conductors of electricity and heat.
• Solids at room temperature except for mercury.
• Malleable.
• Ductile drawn into wires.
• Donate electrons.

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How Do We Distinguish Between Metals, Nonmetals
and Metalloids?

• Elements in the periodic table are divided by a
  heavy, stair step vertical line.
• Non-metals right of line.
• Gasses.
• Non-metals.
• Non-liquid at room temperature except for
  bromium.
• Metalloids straddle the line.
• Properties of both metals and non-metals.

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How Do We Distinguish Between Metals, Nonmetals
and Metalloids?

• Elements in the periodic table are divided by a
  heavy, stair step vertical line.
• Non-metals right of line.
• Gasses.
• Non-metals.
• Non-liquid at room temperature except for
  bromium.
• Metalloids straddle the line.
• Properties of both metals and non-metals.

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How Do Elements Combine to Form Compounds?

• Compound formation.
• The combining of two or more elements by the
  sharing or transfer of their electrons.
• Chemical bonds.
• forces that hold together atoms in molecules and
  ions in crystals.

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Why Are Chemical Bonds So Important?

• Increased compound variety atoms forming bonds
  with other atoms rearrangement of atoms.
• Types of bonding determines
• Solid, liquid or gas states.
• Solid properties hard or soft.
• Liquid properties light, volatile, heavy and
  viscous.
• Melting and boiling points.
• Material strength.
• Molecular shapes determine taste, odor and drug
  actions.

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What Are the Different Types of Chemical Bonds ?

• Ionic bonds the forces between positive and
  negative ions electron transfer.
• Covalent bonds formed by a shared pair of
  electrons between two atoms.
• Polar
• Nonpolar
• Hydrogen bonds hydrogen attached to a small
  electronegative atom such as F, N and O.
• 5-10 as strong as the covalent bond.
• These types of bonds between atoms form compounds
  through rearrangement of atoms.

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Why Are Compounds So Unlike Their Component
Elements?

• Component elements do not keep their original
  properties.
• Component elements are transformed into a
  different substance.
• Sulfur (yellow) Zinc (silvery metal) zinc
  sulfide (white).
• Mercury (silver) oxygen (colorless) mecuric
  oxide (red solid).
• Sodium (soft, silver, reactive metal) chloride
  (greenish-yellow, irritating gas) sodium
  chloride ( white crystal, table salt.

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How/Why Do Reacting Atoms Attempt to Attain a
Stable Electron Configuration?

• Stable electron configuration outermost energy
  level of an atom filled with 8 electrons.
• Octet rule when atoms react to form bonds with
  each other they are really trying to attain a
  stable electron configuration or rule of eight.

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How Are Electrons Represented Symbolically In the
Outer Energy Levels of Atoms?

• Electron dot symbols chemical shorthand for
  writing the core of the atom and its valence
  (outer) electrons which enter into chemical
  reactions.
• An atom becomes an ion when it either loses or
  gains electrons to become a charged particle.
• Writing electron configurations in outer energy
  levels
• Electron loss Na. (group 1A) ionizes to Na1
  e- less reactive with an e- loss (oxidative
  process). ..
  
  ..
• Electron gain - Cl. (group 7A) 1 e- ionizes to
  Cl - less reactive
  if gains an electron (reduction process).

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How Are Ionic Bonds Formed?

• Ionic attractions are one way to combine atoms
  into the formation of compounds.
• Ions of opposite charges are attracted to one
  another ionic bond formation.
• Sodium (Na) clorine (Cl-) sodium chloride
  (NaCl table salt).
• ..
  ..
• Na. Cl. Na Cl -
• .. ..

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How Are Ionic Bonds Formed?

• Periodic table groups 1A and 2A (metals) readily
  react with non-metallic elements in groups 6A and
  7A.
• Form ionic bonds gain or loss of electrons.
• Stable crystal solids are the outcome of these
  reactions.

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How Are the Combination of Simple Ions Noted?

• Naming of ions.
• Positive ions (cations) add word -ion
  sodium atom sodium ion ( loss of electron).
• Negative ions (anions) ending in -ide
  chlorine atom cloride ion ( gaining of
  electron).
• Binary compounds formula for combining simple
  ions of opposite charge.
• Calcium chloride English into chemistry.
• Ca2 and Cl- ions.
• Crossover superscript numbers (charges) but not
  signs CaCl2.
• Ions differ dramatically from the atoms from
  which they are made (Na Cl- NaCl table salt).

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What Is the Difference Between Ionic and Covalent
Bonds?

• Atoms from opposite ends of periodic table (
  very different atoms) combine to form ionic
  bonds.
• Transfer of electrons from one atom to another.
• Similar atoms (same end of periodic table 2
  nonmetal or 2 metal atoms) combine to form
  covalent bonds atoms that share electrons if no
  other kinds of atoms around.
• Bond formation between atoms that are different
  but not different enough to form ionic bonds
  unequal sharing of electrons.

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What Are the Three Types of Covalent Bonds?

• Sharing 1 pair of electrons single bond.
• H-H hydrogen gas H2 a molecule.
• H. H. HH hydrogen bond.
• Sharing 2 pair of electrons double bond.
• OCO carbon dioxide (C4 and O6 valence e-s).
• .. ..
  ..
• C O OCO CO2
  a molecule.
• .. ..
  ..
• Sharing 3 pair of electorns triple bond.
• - N ? N nitrogen (N 5 valence electrons).
• .. ..
• N N NN N2 a molecule.
• . .

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How Do Atoms Enter Into the Unequal Sharing of
Electrons?

• Nonpolar covalent bonds when two identical
  nonmetal atoms combine.
• Polar covalent bonds when 2 atoms of different
  nonmetals combine unequal sharing of electrons
  (not an ionic bond).
• Atoms to right of periodic table are more
  electronegative and tend to gain electrons.
• The greater the electronegativity of an atom the
  greater the pull of electrons in a bond towards
  its end of the bond when involved with covalent
  bonding.
• Hydrogen chloride chlorine end is more negative
  than hydrogen end unequal sharing of electrons
  polar covalent bonding.
• The atom at positive end of bond (H) still has a
  share in the bonding pair of electrons in
  contrast to an ionic bond where one atom
  completely loses an electron.

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What Happens When Two Or More Charged Particles
Bond?

• Polyatomic ions charged particles (hydroxide
  ion OH-) containing 2 or more covalently bonded
  atoms.
• There are many groups of atoms like the hydroxide
  ion that remain together through most chemical
  reactions.
• Polyatomic molecules.
• Many nonmetals often form a number of covalent
  bonds equal to 8 minus the group number.
• 
  .
• Carbon 4 bonds formed methane . C . 4H .
• 
  .

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Names of Covalent Compounds

• Many common names NH4 ammonia.
• Others
• Prefixes (mono-, di-, tri-) for the number of
  atoms of each element.
• CO2 carbon dioxide.
• N2O4 dinitrogen tetraoxide

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Exception to the Octet Rule

• When there are an odd number of valence electrons
  in molecules (free radicals) - NO
• When there are too few electrons to make an octet
  BeX2 BeBr2
• Third period and beyond when there are
  obviously more than 8 electrons that must be in
  the valence level PCl5

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How Are Molecular Shapes of Molecules Determined?

• Valence shell electron pair repulsion theory
  VSEPR theory.
• Electron pairs arrange themselves about a central
  atom in a way that minimizes repulsion between
  like-charged particles.
• They get as far apart as possible.
• Molecules have three dimensional shapes.
• Linear.
• Bent.
• Triangular.
• Pyramidal.
• Tetrahedron.

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What Are the Rules For Determining the Shapes of
Molecules?

• Draw and electron-dot structure in which a shared
  electron pair (bonding pair, BP) is indicated by
  a line. Use dots to show any nonbonding pairs
  (NBPs) of electrons.
• To determine shape, count the number of atoms and
  NBPs attached to the central atom. Note that a
  multiple bond counts only as one set.

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What Are the Rules For Determining the Shapes of
Molecules?

• Determine the number of electron sets and draw a
  shape with connecting lines as if all were
  bonding pairs.
• Sketch this shape, placing the electron pairs as
  far apart as possible. If there is no NBP, this
  is the shape of the molecule. If there are NBPs,
  remove them and erase their connecting lines.
  Leaving the BPs exactly as they were.
• Following examples are the shapes of ammonia
  (NH3) and methane (CH4) respectively using the
  VSEPR rule.

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How Does the Polarity of a Molecule Affect Its
Shape?

• For molecules of 3 or more atoms the orientation
  of the bonds must be considered to determine if
  the molecule as a whole is polar.
• Polar molecules separate centers of or
  charges instead of canceling each other out a
  dipole molecule which will alter its shape as
  predicted by the VSEPR theory.
• Water bent.
• Ammonia pyramidal.
• Methane tetrahedral.

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What Are the Forces That Determine the Physical
States of Matter?

• Shape and polarity of molecules are determined by
  how they interact with each other.
• Intermolecular forces determines the physical
  state of a molecule.
• Gas.
• Liquid.
• Solid.

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How Are the Physical States of Matter Determined?

• Solids and liquids.
• Solids.
• Highly ordered.
• Close contact of atoms
• Atoms only vibrate within confines of solid
  lattice.
• Table salt ionic bonds attractive force.
• Transition from solid to liquid state heat to
  800oC for NaCl held together by very strong
  forces.
• Transition process heat molecular motion
  attractive forces broken.

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How Are the Physical States of Matter Determined?

• Solids and liquids.
• Liquids.
• Like marbles in a box molecules roll over one
  another.
• Less rigidity held in space by attractive forces.
• Transition from liquid to a gas or vapor
  vaporization heat molecular movement
  separation.

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How Are the Physical States of Matter Determined?

• Solids and liquids .
• Gas and liquids process reversal.
• Condensation energy removal movenent conversion of a gas to a liquid.
• Freezing conversion of a liquid to a solid by
  further

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What Are the Interactions That Hold Solids and
Liquids Together?

• Inerionic forces salt crystals.
• Dipole forces.
• Two dipoles attract.
• Force is less than interionic forces.
• Hydrogen bonds.
• Strongly polarized molecules that are small and
  highly electronegative (F, O, and N).
• H-F bond is highly polarized since their opposite
  charges are so close together very strong
  attractions.
• Indicated by dotted lines.
• Water unusually high melting and boiling points
  caoused by hydrogen bonds.

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What Are the Interactions That Hold Solids and
Liquids Together?

• Dispersion forces momentary weak attraction
  forces.
• Electrons constantly move.
• Two ends of molecule are polarized weak
  attraction.
• Electorn rich end charge.
• Electron poor end - charge.

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What Are the Forces Involved in the Formation of
Solutions?

• Solution intimate homogenous mixture of 2 or
  more substances.
• Intimate mixing at ionic and molecular levels.
• Salt in water single ions randomly distributed
  among water molecules.
• Homogenous thorough mixing.
• Salt-water saltiness same at top and bottom of
  container.
• Solute substance being dissolved smaller
  amount salt.
• Solvent substance doing the dissolving.

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What Are the Forces Involved in the Formation of
Solutions?

• Solution formation.
• Easy to dissolve substances of like bonding
  characteristics.
• Nonpolar solutes dissolve best in nonpolar
  solvents.
• Solute dissolves when attractive forces between
  it and the solvent overcome the attractive forces
  operating in the pure solute and in the pure
  solvent.
• Ethyl alcohol water hydrogen bond formation.

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What Are the Forces Involved in the Formation of
Solutions?

• Salt in water? How dissolved in the presence of
  strong ionic bonds?
• Strong ionic bonds are broken by offering an
  attractive alternative to ionic interactions in
  the crystal (salt).
• Reason?
• Water is a dipole.
• Many water molecules surround the ion and orinent
  in such a way that their or side (dipole) is
  towards the solute ro side respectively.
• Ion-dipole interactins overcome ion-ion
  interactions.
• Water a remarkable solvent.
• Reason for nutrients reaching cells.
• How pollutants get into our water supplies.

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Chapter 5 Problem-Solving and Homework
Assignments

• Check the appropriate web page.

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Chapter 5 Study Checklist

• Know the key terms on text page 144.
• Study the answers to the questions in the
  learning objectives for Chapter 5.