Students know atoms combine to form molecules by sharing electrons to form covalent or metallic bond

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Todays Standard Objective
Students know atoms combine to form molecules by
sharing electrons to form covalent or metallic
bonds or by exchanging electrons to form ionic
bonds
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6.1 Intro to Chemical Bonding

• Chemical bond a mutual electrical attraction
  between the nuclei and valence electrons of
  different atoms binding the atoms together.

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6.1 Intro to Chemical Bonding

• Ionic bond chemical bonding that results from
  the electrical attraction between large numbers
  of cations and anions
• What is a cation? An anion?

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6.1 Intro to Chemical Bonding

• Ionic bond

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6.1 Intro to Chemical Bonding

• Covalent Bond Type of bond that results from
  the sharing of electron pairs between two atoms.

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6.1 Intro to Chemical Bonding

• Covalent Bond

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6.1 Intro to Chemical Bonding

• Bonding is rarely purely ionic or purely
  covalent. It usually falls somewhere between
  these two extremes, depending on how strongly the
  atoms of each element attract electrons.

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6.1 Intro to Chemical Bonding

• Electronegativity a measure of an atoms
  ability to attract electrons in a compound
• Polarity having an unequal distribution of charge

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C. Bond Polarity

• Most bonds are a blend of ionic and covalent
  characteristics.

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6.1 Intro to Chemical Bonding

• nonpolar-covalent bond a covalent bond where
  the bonding electrons are shared equally by the
  bonded atoms and have a balance distribution of
  electrical charge.

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6.1 Intro to Chemical Bonding

• polar-covalent bond a covalent bond where the
  bonding electrons have an unbalanced distribution
  of electrical charge.

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Chemical Bonding

• The Octet Rule chemical compounds tend to form
  so that each atom has an octet (8) electrons in
  its highest energy level

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Chemical Bonding

• Electron Dot Notation electron configuration
  showing the atoms valence electrons as dots
  around the element symbol
• F

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Chemical Bonding

• Lewis Structure/structural formula electron
  configuration for two or more bonded atoms
• Unshared Pair or Lone Pair A pair of electrons
  not involved in bonding

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Chemical Bonding

• Lewis Structure Steps
• 1. Determine the total of valence electrons in
  the atoms.
• 2. Arrange atoms. If carbon is present, it is
  central. Otherwise, least electronegative
  element is central.

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Chemical Bonding

• Lewis Structure Steps
• 3. Show shared electrons (bonds) by dashes.
• 4. Fill in unshared electron pairs so that each
  atom (except hydrogen) has an octet.

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Chemical Bonding

• Multiple Bonds
• 1. Double bonds
• C2H4
• 2. Triple bonds
• N2
• C2H2

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Chemical Bonding

• Metallic Bonds a chemical bond formed by the
  attraction of metal atoms and the surrounding sea
  of electrons.

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Chemical Bonding

• Metallic Bonds a chemical bond formed by the
  attraction of metal atoms and the surrounding sea
  of electrons.

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• Metallic Bonding

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Sec 6.2 Covalent Bonding Molecular Compounds

• Todays Standard Objective
• Students know chemical bonds between atoms in
  molecules such as H2, CH4, NH3, H2CCH2, N2, Cl2,
  and many large biological molecules are covalent

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Sec 6.2 Covalent Bonding Molecular Compounds

• Many chemical compounds, including most of the
  chemicals that are in living things and are
  produced by living things, are composed of
  molecules

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Sec 6.2 Covalent Bonding Molecular Compounds

• A molecule is a neutral group of atoms that are
  held together by covalent bonds

Caffeine molecule! Booya!!
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Sec 6.2 Covalent Bonding Molecular Compounds

• A molecular compound is a chemical compound whose
  simplest units are molecules

Water Molecules
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Sec 6.2 Covalent Bonding Molecular Compounds

• A chemical formula indicates the relative numbers
  of atoms of each kind in a chemical compound by
  using atomic symbols and subscript numbers

AgNO3
Subscript number
Atomic Symbol
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Sec 6.2 Covalent Bonding Molecular Compounds

• The chemical formula of a molecular compound is
  referred to as a molecular formula

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Sec 6.2 Covalent Bonding Molecular Compounds

• Monoatomic Neon gas has how many atoms?
• A diatomic molecule has how many atoms?

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Sec 6.2 Covalent Bonding Molecular Compounds

• In nature, chemical bonding is favored because
  most atoms are at lower potential energy when
  bonded to other atoms than they are when
  independent

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Sec 6.2 Covalent Bonding Molecular Compounds

• The distance between two bonded atoms at their
  minimum potential energy, that is, the average
  distance between two bonded atoms, is the bond
  length

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Ionic Bonding
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Bond Polarity and Electronegativity

• Electronegativity
• Electronegativity The ability of one atoms in a
  molecule to attract electrons to itself.
• Pauling set electronegativities on a scale from
  0.7 (Cs) to 4.0 (F).
• Electronegativity increases
• across a period and
• down a group.

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Bond Polarity and Electronegativity
Electronegativity
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Drawing Lewis Structures

• Add the valence electrons.
• Write symbols for the atoms and show which atoms
  are connected to which.
• Complete the octet for the central atom the
  complete the octets of the other atoms.
• Place leftover electrons on the central atom.
• If there are not enough electrons to give the
  central atom an octet, try multiple bonds.