Atomic Structure: Metals, Metalloids, Orbitals, and Principles

Metals, Metalloids, and Non-metals

• Metals: Good conductors of electricity.
• Metalloids: Intermediate between metals and non-metals.
• Non-metals: Poor conductors of electricity.

Atomic Orbitals

The last significant electron shell fills with gas.

Examples of Orbitals

• S orbital
• P orbital
• D orbital
• F orbital

Orbital Shapes

• Orbital S: Spherically symmetric around the atomic nucleus.
• Orbital P: Two flattened areas at the point of contact, oriented according to the coordinate axes.
• Orbital D: Four lobes of alternating signs, with the last being a double lobe surrounded by a ring.
• Orbital F: More complex shapes.

Quantum Principles

1. Pauli Exclusion Principle: No two electrons can have the same quantum numbers.
2. Aufbau Principle: Electrons fill the lowest energy levels first.
3. Hund's Rule: Electrons individually occupy each orbital within a subshell before any orbital is doubly occupied.

Atomic Models

Thomson's Model

Thomson determined that the emitted beam was formed by negative charges, attracted to the positive pole. This occurred regardless of the gas inside the tube, leading to the conclusion that this particle was common to all types of atoms.

Thomson established that an atom must contain equal amounts of negative and positive charges, naming the negative charges electrons (e-).

Rutherford's Model

Rutherford suggested that the positive charges of the atom were concentrated in the center, in the nucleus, with electrons surrounding it.

Rutherford reached this conclusion by bombarding thin metal foils of gold with alpha radiation, surrounded by a zinc sulfide screen that produced flashes upon impact.

Dalton's Atomic Theory

Dalton's tenets:

• All matter is made of atoms.
• Atoms are indivisible and indestructible particles.
• Atoms of the same element are identical and have equal mass.
• Atoms combine in whole-number ratios to form compounds.
• Chemical reactions involve the combination or separation of atoms.