Chemical Formula and Lewis Structure

Water's Chemical Formula

• Chemical formula of water: H₂O, consisting of two hydrogen (H) atoms and one oxygen (O) atom.

Lewis Structure

• Lewis structure depicts oxygen at the center, with two lone electron pairs and two hydrogen atoms bonded.
• Illustrates covalent bonds formed by the sharing of electrons between hydrogen and oxygen.

Shared Electrons and Lone Pairs

• Each hydrogen atom shares one electron with oxygen, resulting in two O-H bonds.
• Oxygen retains two lone pairs of electrons, which are not involved in bonding and influence molecular shape.

VSEPR Theory

• Valence Shell Electron Pair Repulsion (VSEPR) theory states that electron pairs around a central atom minimize repulsion by maximizing distance.
• This leads to a specific arrangement of bonded and lone pairs.

Molecular Shape and Bond Angle

• Water adopts a bent molecular shape instead of a linear structure due to lone pair repulsion.
• Bond angle in water is approximately 104.5 degrees, compressed by lone pair interactions.

Intermolecular Forces

• Intermolecular forces are interactions between molecules that influence physical properties, such as boiling and melting points.
• Water's unique intermolecular forces stem from its molecular characteristics.

Identification of Ions

• Water is a neutral molecule containing no ions, affecting the nature of its interactions compared to ionic compounds.

Polar Molecule Properties

• Water is polar, with a partial positive charge on hydrogen atoms and a partial negative charge on the oxygen atom, leading to significant molecular interactions.

Hydrogen Bonds

• Hydrogen bonding occurs in polar molecules with high electronegativity differences, particularly with fluorine, oxygen, and nitrogen.
• Unique attraction between hydrogen of one molecule and electronegative atoms (O, N, F) results in stronger intermolecular forces known as hydrogen bonds.
• Hydrogen bonds contribute to higher boiling points compared to ordinary dipole-dipole interactions.

Ice Structure and Density

• The solid form of water (ice) has a more open molecular structure, resulting in fewer molecules per volume and lower mass.
• The lower density of ice allows it to float on liquid water, causing lakes to freeze from the top down.