CHE 201 — Chapters 1 & 2 Vocabulary Flashcards

A set of comprehensive vocabulary flashcards covering key definitions, principles, scientists, and subatomic concepts from CHE 201 Chapters 1 and 2.

Matter

Anything that has mass and takes up space.

Atoms

The building blocks of matter.

Element

A substance made of only one kind of atom.

Compound

A substance made of two or more different elements chemically bonded together in a fixed composition.

Pure Substance

Matter with a constant composition and distinct properties, categorized into elements and compounds.

Mixture

A combination of substances in which the components retain their identities and are physically combined in variable proportions.

Homogeneous Mixture

A mixture with a uniform composition throughout.

Heterogeneous Mixture

A mixture with a nonuniform composition.

Law of Constant Composition

Also called the Law of Definite Proportions, states that a pure compound always has the same elemental composition by mass.

Physical Property

A property that can be observed or measured without changing the substance's identity, such as density, color, odor, melting point, and hardness.

Chemical Property

A property that describes a substance's ability to undergo a chemical change.

Physical Change

A change that does not change the identity of the substance, such as melting, freezing, sublimation, and cutting.

Chemical Change

A change that produces one or more new substances, such as combustion, oxidation, decomposition, and burning.

Intensive Property

A property that does not depend on the amount of substance present, such as density, color, and boiling point.

Extensive Property

A property that depends on the amount of substance present, such as mass, volume, and energy.

Filtration

A separation technique used for separating a solid from a liquid.

Distillation

A separation technique that relies on differences in boiling points to separate substances.

Chromatography

A separation technique that separates substances based on differences in solubility and interactions with the materials involved.

SI Base Units

Standard units of measurement including kilogram ($\text{kg}$) for mass, meter ($\text{m}$) for length, Kelvin ($\text{K}$) for temperature, and cubic meter ($\text{m}^3$) for volume.

Metric Prefixes

Prefixes representing powers of ten: kilo- means $10^3$ ($1,000$), milli- means $10^{-3}$ ($0.001$), and pico- means $10^{-12}$.

Density

The ratio of mass to volume, represented by $d = \frac{m}{V}$, with common units of $\text{g/mL}$ and $\text{g/cm}^3$.

Accuracy

How close a measurement is to the true value.

Precision

How close repeated measurements are to one another.

Significant Figures

The digits in a measurement that convey meaningful precision, where nonzero digits, captive zeros, and trailing zeros after a decimal point are significant.

Dimensional Analysis

A method of converting between units using conversion factors so that unwanted units cancel and leave the desired unit.

John Dalton

The scientist who developed the atomic theory in the early 1800s (around 1803–1807) to help explain experimentally derived chemical laws.

Scientific Law

A statement or summary describing how matter behaves.

Scientific Theory

An explanation that attempts to explain why matter behaves as it does.

Law of Conservation of Mass

States that mass is neither created nor destroyed during a chemical reaction, meaning total reactant mass equals total product mass.

Proton

A subatomic particle located in the nucleus with a positive ($+1$) charge, discovered by Ernest Rutherford in 1919.

Neutron

A subatomic particle located in the nucleus with no charge ($0$), discovered by James Chadwick in 1932.

Electron

A subatomic particle located outside the nucleus with a negative ($-1$) charge and very small mass, discovered by J.J. Thomson.

J.J. Thomson

The scientist who discovered the electron using cathode-ray tubes, calculated its charge-to-mass ratio as $1.76 \times 10^8\,\text{C/g}$, and proposed the plum pudding model.

Cathode Rays

Streams of negatively charged electrons originating from the negative electrode (cathode) that bend toward positively charged plates and magnetic fields.

Plum Pudding Model

An atomic model proposed by J.J. Thomson in which negative electrons were embedded in a positively charged sphere of matter.

Robert Millikan

The scientist who determined the magnitude of the electron's charge ($1.602 \times 10^{-19}\,\text{C}$) using the oil-drop experiment.

Radioactivity

The spontaneous emission of radiation by an atom, first observed by Henri Becquerel and further studied by Marie and Pierre Curie.

Alpha Radiation ($\alpha$)

A type of radiation carrying a positive charge.

Beta Radiation ($\beta$)

A type of radiation carrying a negative charge.

Gamma Radiation ($\gamma$)

A type of radiation carrying no charge (neutral).

Ernest Rutherford

The scientist who conducted the gold foil experiment with alpha particles, proposed the nuclear model, discovered the atomic nucleus, and discovered the proton in 1919.

Nucleus

A very small, dense region at the center of the atom containing protons and neutrons and housing most of the atom's mass.

James Chadwick

The scientist who discovered the neutron in 1932.

Atomic Number ($Z$)

The number of protons in an atom, which equals the number of electrons in a neutral atom.

Mass Number ($A$)

The total number of protons plus neutrons in an atom ($A = \text{protons} + \text{neutrons}$).

Atomic Notation (${}_Z^A\text{X}$)

Standard atomic representation where $\text{X}$ is the elemental symbol, $A$ is the mass number, and $Z$ is the atomic number.