Essential Definitions: Chemistry, Geology, and Atmospheric Science Concepts

Fundamental Concepts in Physical Science

I. Atomic and Chemical Structure

Basic Constituents of Matter

Atom

The basic or fundamental constituent of matter.

Element

A species of atoms having the same number of protons in their atomic nuclei.

Molecule

An electrically neutral group of two or more atoms of the same element held together by chemical bonds.

Compound

An electrically neutral group of two or more atoms of different elements held together by chemical bonds.

Ion

An atom or molecule in which the number of electrons is not equal to the number of protons. (Note: Extracting electrons can lead to plasma.)

Isotope

An element made up of atoms that have the same number of protons (atomic number) but a different number of neutrons (mass number).

Periodic Table Organization

• Groups: Vertical columns
• Periods: Horizontal rows

Historical Atomic Models

Key models proposed by scientists:

• Dalton: Billiard Ball Model
• Thomson: Plum Pudding Model
• Rutherford: Planetary Model
• Bohr: Planetary Model with electron shell arrangements
• Chadwick: Discovery of the neutron (often referred to as the 'nuclear glue')

II. Earth Science and Geology

Supercontinents Through Time

Rodinia — Pannotia — Pangea

Structure of Earth

The Earth's structure can be defined by composition or mechanical properties:

Compositional Layers:

1. Crust
2. Mantle
3. Outer Core
4. Inner Core

Mechanical Layers:

Lithosphere, Asthenosphere, Mesosphere

Geological Materials

Mineral

A naturally formed solid substance, typically inorganic, resulting from geological processes. Minerals are defined by a specific chemical composition and crystal structure.

Magma

A mixture of molten rock, solids, and gases found beneath the Earth's surface (also expected on other terrestrial planets and satellites).

Theory of Plate Tectonics

The Earth's lithosphere is divided into large tectonic plates that interact at boundaries:

• Divergence: Plates move apart.
• Convergence: Plates move toward each other.
• Transform: Plates slide past each other.

Seismic Activity and Measurement

Earthquake

The perceptible shaking of the Earth's surface resulting from the sudden release of energy in the Earth's crust.

Epicenter

The point on the Earth's surface directly above the focus (hypocenter) of an earthquake, usually located on a tectonic plate boundary (fault).

Richter Scale

Quantifies the magnitude of an earthquake based on the energy released.

Volcanoes

A rupture in the crust of a planetary-mass object (such as Earth) that allows hot lava, ash, and gases to escape from a magma chamber below the surface.

III. Atmospheric Science and Weather

Atmospheric Layers

1. Troposphere
2. Stratosphere
3. Mesosphere
4. Thermosphere
5. Exosphere

Severe Weather Phenomena

Tropical Cyclone

A rapidly rotating and organized system of clouds with a well-defined spiral arrangement of thunderstorms and heavy rain.

Hurricanes

Large tropical cyclones that form over warm sea surfaces, typically in the belt around the Equator, characterized by rotation and translation.