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GOB Chemistry: Covalent Bonding, Molecular Polarity, Reactions, and Energy

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Terms in this set (29)

  • What is a covalent bond?

    A covalent bond forms when two atoms share a pair of valence electrons, creating a stable arrangement by satisfying the octet rule or duet for hydrogen.

  • How is the strength and length of a covalent bond determined?

    By the balance between the attraction of positively charged nuclei to shared electrons and the repulsion between the nuclei of the bonded atoms.

  • What is a lone pair in covalent bonding?

    A lone pair is a pair of valence electrons on an atom that are not shared with another atom and are represented as two dots in Lewis structures.

  • What elements naturally occur as diatomic molecules?

    Seven elements occur naturally as diatomic molecules, such as H2, N2, and O2, bonded covalently.

  • What types of bonds do oxygen and nitrogen form in their diatomic molecules?

    Oxygen forms a double bond (two shared pairs), and nitrogen forms a triple bond (three shared pairs) to satisfy the octet rule.

  • When do covalent bonds form according to the periodic table?

    Covalent bonds form between two nonmetals or between a nonmetal and a metalloid, as nonmetals tend to share electrons rather than lose them.

  • What is the central atom in a molecule?

    The central atom is the atom bonded to more than one other atom, often carbon, nitrogen, or oxygen in covalent molecules.

  • How many covalent bonds does carbon typically form and why?

    Carbon typically forms four covalent bonds because it has four valence electrons and needs four more to complete its octet.

  • What are the four general steps for drawing Lewis structures?
    1. Count total valence electrons.
    2. Identify the central atom.
    3. Connect atoms ensuring octets (duet for H).
    4. Use multiple bonds if needed.
  • What is an exception to the octet rule involving boron?

    Boron often forms stable compounds with only six shared electrons, not completing an octet, due to having fewer valence electrons.

  • What is the Valence Shell Electron Pair Repulsion (VSEPR) theory used for?

    VSEPR theory predicts molecular shapes by counting electron groups around a central atom and considering electron pair repulsions.

  • What molecular shape corresponds to two electron groups around a central atom?

    A molecule with two electron groups is linear with a bond angle of 180°.

  • What molecular shape corresponds to three electron groups around a central atom?

    A molecule with three electron groups is trigonal planar with bond angles of approximately 120°.

  • What molecular shape corresponds to four electron groups around a central atom?

    A molecule with four electron groups is tetrahedral with bond angles of approximately 109.5°.

  • How do you name binary molecular compounds?

    Name the first nonmetal by element name, the second with an -ide ending, and use prefixes to indicate the number of atoms (omit 'mono' for the first element).

  • What is electronegativity and how does it affect bond polarity?

    Electronegativity is an atom's ability to attract shared electrons; differences in electronegativity cause bonds to be nonpolar, polar covalent, or ionic.

  • What electronegativity difference ranges correspond to bond types?

    0-0.4: nonpolar covalent; 0.5-1.7: polar covalent; 1.8-3.3: ionic bonds.

  • What are the three major types of intermolecular forces?

    London dispersion forces, dipole-dipole forces, and hydrogen bonds.

  • What causes London dispersion forces?

    Temporary dipoles formed by momentary uneven electron distribution induce attractions between nonpolar molecules.

  • What is a hydrogen bond?

    A special dipole-dipole attraction between a hydrogen atom covalently bonded to O, N, or F and a lone pair on another O, N, or F atom.

  • What is a chemical reaction?

    A process where bonds break, atoms rearrange, and new bonds form to create new substances, often with observable changes.

  • What are the four main types of chemical reactions?

    Combination, decomposition, single replacement, and double replacement reactions.

  • What is a redox reaction?

    A reaction involving the transfer of electrons where oxidation is loss of electrons and reduction is gain of electrons.

  • What is a mole in chemistry?

    A mole is \(6.02\times10^{23}\) particles of a substance, used to count atoms or molecules.

  • How is molar mass defined?

    Molar mass is the mass of one mole of a substance, expressed in grams per mole (g/mol), numerically equal to atomic or formula mass.

  • What is the theoretical yield in a chemical reaction?

    The maximum amount of product predicted from the limiting reactant in a chemical reaction.

  • What factors affect the rate of a chemical reaction?

    Reactant concentration, temperature, and the presence of a catalyst affect reaction rate by influencing collision frequency and activation energy.

  • What is activation energy?

    The minimum energy required for a chemical reaction to proceed, represented as a hill in an energy diagram.

  • What is Le Chatelier’s principle?

    When a system at equilibrium is disturbed, it shifts to counteract the change and restore equilibrium.