Atomic Structure and Theory Basics

• Atoms consist of protons, neutrons, and electrons.
• Atomic mass is the sum of protons and neutrons.

Atomic Theory

• Dalton's atomic model described atoms as indivisible, solid spheres, known as the Billiard Ball Model.
• Thomson discovered the electron and proposed the Plum Pudding Model, where electrons are scattered in a positive charge.
• Rutherford discovered the dense, positive nucleus and created the Nuclear Model through the gold foil experiment.
• Bohr proposed that electrons orbit the nucleus in fixed energy levels, leading to the Bohr-Rutherford Model.

Atomic Structure Basics

• Protons carry a positive charge and reside in the nucleus.
• Neutrons have no charge and are located in the nucleus.
• Electrons have a negative charge and orbit the nucleus.
• The first orbital holds up to 2 electrons.
• The second orbital holds up to 8 electrons.
• The third orbital also holds up to 8 electrons for simpler atoms.

Neutral Atoms and Ions

• In a neutral atom, the number of protons equals the number of electrons, matching the atomic number.
• Ions are formed when atoms gain or lose electrons.
• A cation is a positive ion, such as Na⁺ (Sodium ion).
• An anion is a negative ion, like Cl⁻.

Periodic Table Trends

• Group 1 elements tend to donate electrons to achieve a stable outer shell.
• Group 6 and 7 elements are highly reactive and attract electrons strongly, exhibiting high electronegativity.

Chemical Bonding

• Ionic bonds form through electron transfer between atoms, typically between metals and non-metals.
• Ionic compounds have high melting points, are soluble in water, and conduct electricity in solution.
• Covalent bonds form through electron sharing between atoms, generally between non-metals.
• Covalent compounds have low melting points, poor conductivity, and are often insoluble in water.

Naming and Formulas

• For ionic compounds, name the metal first, followed by the non-metal with an "-ide" ending, charges must be balanced to write correct formulas.
• For molecular compounds, prefixes indicate the quantity of each element (mono-, di-, tri-, etc.) which is used to construct the formulas.

Prefixes for Molecular Compounds

• 1: Mono-
• 2: Di-
• 3: Tri-
• 4: Tetra-
• 5: Penta-
• 6: Hexa-
• 7: Hepta-
• 8: Octa-
• 9: Nona-
• 10: Deca-

Diatomic Elements

• The diatomic elements are H₂, N₂, O₂, F₂, Cl₂, Br₂, and I₂.