Unit 2 Chemistry

Define electronegativity.

• The temperature at which a substance changes state.

• The energy released during a chemical reaction.

• A measure of the
  ability of an atom
  (or group of atoms)
  to attract shared
  electrons.

• The measure of an atom's size.

What is Coulomb's Law for electronegativity?

• It increases across a period, because it wants to fill its shell. It decreases down a group, because there is an increase in distance, leading to a decrease in force.

• Coulomb's Law states that electronegativity increases with atomic size.
• Electronegativity is defined by the distance between charged particles.
• Coulomb's Law measures the strength of electronegativity directly.

Define an ionic bond.

• 1. An ionic bond happens when two metals bond by sharing electrons evenly.

• An ionic bond (metal and non-metal) is a transfer of electrons, due to large difference in electronegativity between two atoms.

• • An ionic bond occurs when two atoms equally share electrons without charge separation.

• • An ionic bond forms between two atoms with the same electronegativity, leading to no electron transfer.

Define a polar covalent bond.

• A polar covalent bond (two non-metals) is where two atoms share electrons unequally, because of a moderate difference in electronegativity.

• • A polar covalent bond is when electrons are transferred completely from one atom to another, forming ions.

• • A polar covalent bond occurs when two atoms share electrons equally, with no charge separation.

• 1. A polar covalent bond happens only between two identical nonmetals that have no difference in electronegativity.

Define a non-polar covalent bond.

• • A non-polar covalent bond occurs when a metal and a nonmetal transfer electrons completely.

• • A non-polar covalent bond happens when one atom donates its electrons entirely to the other.

• 1. A non-polar covalent bond forms when two atoms have a large difference in electronegativity, causing one atom to attract electrons more strongly than the other.

• A non-polar covalent bond (two non-metals) is when the two atoms share electrons equally, because of little or no difference in electronegativity.

What is the electronegativity difference range for a non-polar covalent bond?

• Less than 0.5

• 1. Exactly 0

• • Between 0.4 and 1.7

• • Less than 1

What is the electronegativity difference range for a polar covalent bond?

• 1.8-2.5

• 2.6-3.0

• 0.5-1.7

• 0.1-0.3

What is the electronegativity difference range for an ionic bond?

• Greater than 1.7
• Exactly 1.5
• Less than 0.5
• Between 0.5 and 1.0

What is the trend in bond polarity?

• All bonds have the same polarity regardless of electronegativity.
• Bond polarity decreases with greater electronegativity differences.
• As the electronegativity difference increases, the bond becomes more polar and vice-versa.

• Bond polarity is unaffected by electronegativity differences.

Define metallic bonding.

• Metallic bonding is the sharing of electrons between two non-metal atoms.
• Metallic bonding occurs only in solid metals at high temperatures.
• Metallic bonding is the attraction between non-metal atoms.
• Metallic bonding is the attraction between metal ions and a sea of delocalized (spread out) electrons.