UNIT 2: Classification of Matter and Atomic Theory Flashcards

Matter

Anything that has mass and occupies space.

Mass

The amount of matter an object contains.

Volume

The amount of space occupied by an object.

Extensive Property

A property that depends on the amount of matter in a sample.

Intensive Property

A property that depends on the type of matter in a sample, not the amount.

Molecules

Formed when two or more atoms bond together chemically.

States of Matter

Solid, liquid, gas, plasma.

Crystalline Solids

Solids with particles arranged in an orderly, geometric pattern.

Amorphous Solids

Solids with particles randomly distributed without any long-range pattern.

Vapor

A gaseous state of a substance that is generally a liquid or solid at room temperature.

Pure Substance

A substance made of a single type of atom or molecule with the same characteristics in all samples.

Mixture

Matter with varying composition from one sample to another, containing multiple types of particles.

Elements

Pure substances that cannot be broken down into simpler substances by chemical reactions.

Compounds

Chemical combinations of elements composed of molecules with two or more different kinds of atoms.

Homogeneous

A mixture with uniform composition throughout.

Heterogeneous

A mixture without uniform composition throughout.

Physical Changes

Processes that alter the state or appearance of matter without changing its composition.

Physical Properties

Characteristics of matter that can be changed without altering its composition.

Chemical Properties

Characteristics that determine how the composition of matter changes when in contact with other matter or energy.

Chemical Changes

Changes that alter the composition of matter by rearranging atoms into new molecules.

Chemical Symbol

One or two letter representation of an element where the 1st letter is always capital.

Chemical Formula

An expression indicating the number and type of atoms in a molecule of a compound.

Periodic Table

An arrangement of elements separated into groups based on repeating properties.

Period

Each horizontal row of the periodic table.

Group

Each vertical column of the periodic table where elements have similar properties.

Atomic Theory

A well-tested set of ideas regarding the existence and behavior of atoms.

Brownian Motion

The random motion of particles in a fluid caused by unproven atomic particles.

Leucippus and Democritus

First proposed the idea that matter is made of tiny particles, introducing the concept of atoms.

Atomos

The Greek word for uncuttable or indivisible, used to describe the concept of atoms.

Conservation of Mass

The principle that states even if matter changes shape or form, its mass remains constant.

John Dalton

Transformed Democritus's ideas into a scientific theory, proposing that all elements are composed of indivisible particles called atoms.

Antoine Lavoisier

French Chemist who contributed to the understanding of the general behavior of atoms.

J.J. Thompson

Demonstrated that atoms are divisible into smaller parts and discovered electrons.

Robert A. Millikan

Calculated the charge of an electron and its mass through the oil drop experiment.

Earnest Rutherford

Discovered the nucleus of an atom through the gold foil experiment and identified protons.

Niels Bohr

Developed a new atomic model where electrons orbit the nucleus in specific paths and introduced the concept of energy levels.

Werner Heisenberg

Introduced the Uncertainty Principle and contributed to the development of Quantum Theory.

Principal Quantum Numbers

Energy levels labeled by n, with values 1, 2, 3, 4...

Orbital Shapes

Shapes where electrons are found 90% of the time

Quantum Mechanical Model

Describes electron behavior using Schrödinger Equation

Electron Cloud

Region around nucleus where electrons are likely found

Wavelike Behavior

Particles can behave as waves, demonstrated by Davisson-Germer experiment

Electron Microscope

Invented due to electrons' small wavelength

Atomic Nucleus

Contains protons and neutrons, determines element's identity

Atomic Number

Number of protons defining an element's identity

Isotopes

Versions of an atom with different mass numbers

Average Atomic Mass

Weighted average of isotopes' atomic masses

Nucleons

Protons and neutrons in the nucleus

Strong Nuclear Force

Force holding nucleus together, strongest force in physics

Relative Atomic Mass

Sum of protons and neutrons averaged across all atoms

Isotope Mass Number

Total nucleons in an isotope's nucleus

Electron Configuration

Arrangement of electrons in an atom's orbitals

Quantum Model Limitation

Inability to predict exact electron locations

Louis de Broglie

Proposed wave-particle duality for matter

Clinton Davisson

Demonstrated electron wave behavior

Erwin Schrödinger

Developed mathematical model for electron behavior

Bohr Model

Described electrons moving in circular orbits

Rutherford Model

Described electrons orbiting nucleus

Neutrons

Neutral particles in the nucleus

Electron

Negatively charged particle orbiting nucleus

Proton

Positively charged particle in the nucleus

Electron Paths

Not specified in quantum model, unlike Bohr model

Electron Density

Higher near nucleus, lower in less dense areas