Atomic Structure and Chemistry

Study Notes

Atoms are composed of three main particles: protons, neutrons, and electrons
Protons have a positive charge, neutrons have no charge (neutral), and electrons have a negative charge

An isotope is a variant of a chemical element that differs in neutron number, having the same number of protons
An ion is an atom or molecule with a positive (cation) or negative (anion) electrical charge due to the loss or gain of one or more electrons

Ionic bonds: formed when one or more electrons are transferred from one atom to another, resulting in positively and negatively charged ions that attract each other
Covalent bonds: formed when atoms share electrons to achieve a stable electron configuration
Types of covalent bonds:
- Polar covalent bonds: electrons are shared unequally between atoms, resulting in partial positive and negative charges
- Nonpolar covalent bonds: electrons are shared equally between atoms, resulting in no net charge

Water molecule (H2O) has a bent shape, with two hydrogen atoms covalently bonded to an oxygen atom
Polarity of water molecules: oxygen atom is more electronegative, creating a partial negative charge (δ-) and partial positive charges (δ+) on hydrogen atoms
Formation of hydrogen bonds: positively charged hydrogen atoms in one water molecule are attracted to negatively charged oxygen atoms in neighboring water molecules
Strength of hydrogen bonds: weaker than covalent or ionic bonds, but significant and crucial for structural stabilization
Properties of water: high surface tension, cohesion, adhesion, and ability to dissolve a wide range of substances

pH is a measure of the acidity or basicity of a solution, related to the concentration of hydrogen ions
More hydrogen ions result in a more acidic solution

Hydrogen bonding is associated with properties such as surface tension, boiling point, and unique properties of water
Hydrophobic materials are not soluble in water due to non-polar nature, while hydrophilic molecules are attracted to water and form favorable interactions
Water is essential for life on Earth, serving as a solvent, regulating temperature, supporting habitats, transporting nutrients, and participating in metabolic processes