Chemistry Polarity Flashcards

Molecular Polarity

• Cl2 is a non-polar molecule due to equal electron distribution between two chlorine atoms.
• Polarity in trigonal planar molecules depends on the atoms involved: non-polar if the same atoms are present, polar if different.

Molecular Geometry and Angles

• Trigonal planar shape has bond angles of 120 degrees.
• Tetrahedral shape features bond angles of 109.5 degrees.
• Bent shape exhibits bond angles of 104.5 degrees.
• Linear shape has bond angles of 180 degrees.
• Trigonal pyramidal geometry consists of 3 bonds and 1 lone pair, with bond angles of 107 degrees.

Polarity Characteristics

• Bent molecules are always polar.
• Tetrahedral shapes remain non-polar when all peripheral atoms are identical.
• Trigonal pyramidal structures are inherently polar due to uneven charge distribution.

Significance of Polarity

• Polarity is a helpful concept for understanding molecular behavior, even if not of direct concern.
• Only covalent bonds can exhibit polarity.

Bonding Concepts

• A polar covalent bond arises when electrons are shared unequally between atoms.
• A non-polar bond occurs when electrons are shared equally.
• Electronegativity measures an atom's ability to attract electrons in a chemical compound.

Electronegativity Trends

• Electronegativity increases across a period on the periodic table.
• Electronegativity decreases down a group.

Shielding Effect

• Shielding occurs when core electrons block the attractive force of the nucleus on valence electrons.

Electronegativity Differences and Bonding Types

• A difference in electronegativity indicates polarity in bonds:
  • Polar bonds have a difference of 0.5 to 1.9.
  • Non-polar bonds feature a difference of 0.0 to 0.4.
  • Ionic bonds typically arise with a difference greater than 1.9, leading to the formation of charged ions, generally between metals and non-metals.

Molecular and Compound Definitions

• A molecule is defined as two or more atoms held together by covalent bonds (example: H2O).
• A compound consists of two or more elements chemically combined (examples: H2O, NaCl).

Octet Rule

• The octet rule states that atoms tend to lose, gain, or share electrons to achieve a full set of eight valence electrons, promoting stability.

Diatomic Molecules

• BrINClHOF refers to the diatomic elements: Bromine, Iodine, Nitrogen, Chlorine, Hydrogen, Oxygen, and Fluorine.

Lewis Dot Structure

• A Lewis Dot Structure is a diagram representing a molecule using dots to indicate valence electrons, providing insight into bonding and molecular configuration.

Test your knowledge on the polarity of molecules and their shapes with these flashcards. Learn about terms like polar, nonpolar, and various molecular geometries like trigonal planar and tetrahedral. Great for chemistry students looking to reinforce their understanding of molecular structures.