Chemistry Notes: Hydrogen Bonds and Functional Groups

Hydrogen Bond

The attraction of a hydrogen atom to an electronegative atom, commonly oxygen (O) or nitrogen (N).

Electronegative Atoms (in H-bonding)

Atoms like oxygen or nitrogen that pull electrons towards themselves, creating partial negative charges and attracting partially positive hydrogen atoms.

Polarity in a Water Molecule

Oxygen in H_2O is electronegative, gaining a partial negative charge, while hydrogen atoms acquire partial positive charges, leading to attraction between water molecules.

Individual Hydrogen Bond Strength

Individually, hydrogen bonds are generally weak and relatively easy to break.

Collective Hydrogen Bond Strength

Their strength is significantly bolstered by their sheer number, as each water molecule can form hydrogen bonds with approximately four other water molecules, creating an extensive network.

Functional Groups

Specific groups of atoms within molecules responsible for their characteristic chemical reactions and determining their chemical properties and reactivity.

Hydroxyl Group

Structure: -OH. Class: Alcohols. Properties: Polar, forms hydrogen bonds, increases water solubility.

Carbonyl Group

Structure: -C(=O)- (a carbon atom double-bonded to an oxygen atom). Classes: Ketones (within a carbon chain) and Aldehydes (at the end of a chain). Properties: Polar, reactive.

Carboxyl Group

Structure: -COOH or -C(=O)OH (carbonyl linked to hydroxyl). Class: Carboxylic acids. Properties: Acidic (donates H^+), polar, forms hydrogen bonds.

Amino Group

Structure: -NH_2. Class: Amines. Properties: Basic (accepts H^+), polar, important in amino acids and proteins.

Phosphate Group

Structure: $$-O