Chapter 1: Scientific Measurements - Vocabulary Flashcards

Comprehensive vocabulary flashcards covering key definitions, principles, unit definitions, and key visual models from Chapter 1 (Scientific Measurements).

Empirical fact

An observation or data point collected during an experiment that represents something directly seen, heard, tasted, felt, smelled, or measured.

Scientific law

A concise verbal or mathematical statement (often an equation such as $PV = nRT$) based on repeated experimental results that describes what happens in nature without explaining why.

Hypothesis

A tentative explanation of experimental data or observations that makes testable predictions and leads to further experimentation.

Theory

A thoroughly tested explanation of how nature behaves that can be refined with new experimental results but can never be proven absolutely correct.

Scientific method diagram

The cyclical process showing how empirical facts and scientific laws lead to hypotheses, which are tested to form theories that predict new observations.

Atoms

Tiny submicroscopic particles that make up all chemical substances and represent the smallest particle that retains all properties of a given element.

Matter

Anything that has mass and occupies space.

Mass

A measurement of the quantity of matter in an object, which remains constant regardless of location.

Weight

The force with which an object is attracted by gravity, which varies depending on the local gravitational field strength.

Chemical reaction

A transformation that alters the chemical composition of substances, converting them into new substances with distinct physical properties.

Decomposition reaction

A chemical reaction in which a single substance is broken down into two or more simpler substances, such as decomposing molten sodium chloride into sodium metal and chlorine gas using electric current.

Element

A pure substance that cannot be decomposed into simpler materials by chemical reactions and consists of only one type of atom.

Compound

A pure substance formed from two or more different elements combined in fixed ratios by mass that can be broken down into elements by chemical changes.

Pure substance

Matter (either an element or a compound) that has a constant chemical composition regardless of its source.

Mixture

A combination of two or more substances in variable proportions that can be separated into pure components by physical means.

Homogeneous mixture

A mixture (also called a solution) that exhibits uniform properties and composition throughout the entire sample.

Heterogeneous mixture

A mixture containing two or more distinct regions or phases, each possessing its own set of physical properties.

Classification of matter flowchart

A framework categorizing matter into pure substances (compounds and elements) with constant composition, and mixtures (homogeneous and heterogeneous) with variable composition.

Physical change

A process in which a substance alters its physical state or appearance without changing its underlying chemical composition or forming new substances.

Chemical change

A process in which one or more substances undergo a change in chemical makeup, resulting in the formation of new substances with different physical properties.

Particle arrangement in states of matter

Visual representations comparing solids (particles packed closely with restricted motion), liquids (particles close together but able to flow), and gases (particles widely separated expanding to fill the container).

Physical property

A characteristic of a substance, such as color, electrical conductivity, melting point, or boiling point, that can be observed without altering its chemical identity.

Chemical property

A characteristic describing a substance's capacity to undergo specific chemical reactions and alter its chemical makeup.

Intensive property

A physical or chemical property that is independent of sample size and can be used to identify a substance.

Extensive property

A property, such as mass or volume, that directly depends on the size or quantity of the sample.

Quantitative observation

An observation expressed using numerical measurements obtained with an instrument.

Qualitative observation

A non-numerical observation describing non-quantitative characteristics such as color or rapid boiling.

International System of Units (SI)

The standard metric-based system of units used in scientific measurements, established upon seven fundamental base units.

Absolute zero

The theoretical zero point on the Kelvin temperature scale ($0\,\text{K}$ or $-273.15\,^{\circ}\text{C}$), representing nature's lowest possible temperature.

Accuracy

How close an experimental measurement is to the true or accepted value.

Precision

How closely repeated measurements of the same quantity agree with one another.

Accuracy vs. precision target visual

Diagram illustrating Golfer 1 (precise, inaccurate), Golfer 2 (imprecise, inaccurate), and Golfer 3 (accurate, precise).

Scientific notation

A system of expressing numbers as a value between 1 and 10 multiplied by a power of 10 to unambiguously indicate the number of significant figures.

Exact numbers

Numbers derived from definitions or direct counting that possess no uncertainty and have an infinite number of significant figures.

Conversion factor

A ratio equal to 1 formed from a valid equality between units, used in dimensional analysis to convert measurements from one unit to another.

Density

An intensive property defined as the ratio of an object's mass to its volume ($d = \frac{m}{V}$).

Specific gravity

A dimensionless ratio comparing the density of a substance to the density of water at the same temperature.