Atoms and Atomic Theory Quiz

Atoms and Atomic Theory

Democritus

• Greek philosopher who named the smallest unit of matter "atomos," meaning "not to be cut."
• Proposed that atoms are small, hard particles of the same material, varying in shape and size.
• Believed in an infinite number of atoms.

Dalton’s Atomic Theory

• All matter consists of atoms, which are indivisible.
• Atoms of the same element have identical mass and properties.
• Atoms of different elements vary in properties.
• Chemical reactions rearrange atoms, forming new substances.

Historical Models of the Atom

John Dalton (1803)

• Coined the term "atom," derived from Greek, meaning "indivisible."
• Stated that atoms are indivisible and elements are identical; compounds consist of different atoms.

J.J. Thomson (1904)

• Proposed the Plum Pudding Model, where electrons are distributed in a positively charged "soup."
• Discovered the electron, demonstrating that atoms contain smaller particles.

Ernest Rutherford (1911)

• Developed the Nuclear Model, revealing that atoms consist of a small, dense nucleus containing protons.
• Introduced the quantum mechanical model, indicating electrons occupy specific energy levels, calculated by 2n².

Niels Bohr (1913)

• Proposed the Planetary Model, where protons and neutrons are in the nucleus, and electrons orbit at fixed distances and energies.
• Modified Rutherford’s model, emphasizing distinct energy levels.

Erwin Schrödinger (1926)

• Present the Wave Model, stating electrons behave as both particles and waves.
• His model is recognized as the most accurate representation of atomic structure.

Properties of Subatomic Particles

Electrons

• Negatively charged particles located around the nucleus.

Protons

• Positively charged particles located within the nucleus.

Neutrons

• Neutral particles situated in the nucleus.

Isotopes

• Variants of atoms with the same number of protons but differing numbers of neutrons.

Isotope Notation

• Displays additional information, including mass and atomic numbers.

Key Isotopes

• Tritium, Deuterium, Protium.

Electron Configuration

Valence Electrons

• Electrons in the outermost shell involved in chemical bonding.

Aufbau Principle

• Describes the process for establishing the electronic configuration of atoms or ions.

Hund’s Rule and Pauli Exclusion Principle

• Hund’s Rule addresses maximum multiplicity in electron configurations.
• Pauli Exclusion Principle states no two electrons can share the same four quantum numbers.

Quantum Numbers

• Define properties of atomic orbitals and their associated electrons.

Four Types of Quantum Numbers

• Principal Quantum Number (n): Indicates main energy levels.
• Orbital Quantum Number (l): Defines shape of orbital (S=0, P=1, D=2, F=3).
• Magnetic Quantum Number (ml): Describes orientation in space.
• Spin Quantum Number (ms): Indicates electron spin (+1/2 or -1/2).

Fundamental Chemical Laws

Antoine Lavoisier

• Advocated measurement as a core aspect of chemistry.

Law of Conservation of Mass

• States mass cannot be created or destroyed in a chemical reaction.

Law of Definite Proportions

• Each compound contains elements in fixed mass ratios, demonstrating consistency in composition.

John Dalton’s Contribution

• Emphasized that compounds have a consistent atomic makeup.

Law of Multiple Proportions

• When two elements form multiple compounds, the mass ratios of the second element with respect to the first can be expressed as small whole numbers.

Properties of Matter

Matter

• Defined as anything that occupies space and has mass, including air, glass, and other substances.

Composition of Matter

• Refers to the types and quantities of simpler substances comprising a material.

Substance

• A type of matter with a defined and fixed composition.

Properties

• Characteristics unique to each substance, which help identify it.

Physical Properties

• Observable traits that do not change a substance’s identity.

Physical Change

• A transformation affecting appearance without altering composition.

Chemical Properties

• Traits shown during interactions with other substances.

States of Matter

Solid

• Maintains a fixed shape and structure; particles are closely packed and organized.

Liquid

• Adopts the shape of its container up to its volume; particles are close but disorganized.

Gas

• Fills the entire container, lacking a defined shape; particles are far apart and move freely.