Introductory Chemistry: Chapters 2, 3, and 4

Comprehensive vocabulary flashcards covering measurement, problem-solving, matter, energy, atomic structure, and the periodic table from Chapters 2, 3, and 4 of Introductory Chemistry.

Scientific Notation

A standard system for expressing very large or very small numbers, composed of a decimal part between $1$ and $10$ multiplied by an exponential part of $10$ raised to an integer exponent $n$.

Precision

The degree of certainty or reproducibility in a measured quantity, reflected in scientific reporting by the number of reported digits, where more digits indicate greater precision.

Exact Numbers

Numbers that have an unlimited number of significant figures, originating from exact counting of discrete objects, defined quantities (such as $1\,\text{in.} = 2.54\,\text{cm}$), or integral numbers that are part of an equation.

International System of Units (SI Units)

The standard metric-based unit system adopted for scientific measurements worldwide.

Meter

The SI base unit of length (symbol $\text{m}$), defined in 1983 as the distance that light travels in a vacuum in $1 / 299{,}792{,}458\,\text{s}$.

Kilogram

The SI base unit of mass (symbol $\text{kg}$), defined by fixing the numerical value of Planck's constant to $6.62607015 \times 10^{-34}\,\text{kg}\cdot\text{m}^2/\text{s}^2$.

Second

The SI base unit of time (symbol $\text{s}$), defined using an atomic clock as the duration of $9{,}192{,}631{,}770$ periods of the radiation emitted from a specific transition in a cesium-133 atom.

Mass

A fundamental physical property that quantifies the amount of matter within an object, independent of gravitational force.

Weight

A measure of the gravitational pull exerted on the matter of an object, which varies depending on the local gravitational field.

Derived Unit

A unit formed from mathematical combinations of other base units, such as cubic meters ($\text{m}^3$) or cubic centimeters ($\text{cm}^3$) for volume.

Dimensional Analysis

A problem-solving method that uses units as algebraic guides to formulate calculations, cancel units systematically, and verify solutions.

Conversion Factor

A fractional ratio constructed from two quantities known to be equivalent, mathematically equal to $1$, used to convert a quantity from one unit to another.

Solution Map

A visual diagram outlining the sequential steps, conversion factors, or equations required to transition from the given starting information to the desired endpoint.

Density

A fundamental physical property of a substance defined as the ratio of its mass to its volume ($d = \frac{m}{V}$), commonly reported in units of $\text{g/cm}^3$ or $\text{g/mL}$.

Matter

Anything that occupies space and has mass, composed fundamentally of atoms and molecules.

Atoms

Submicroscopic particles that constitute the fundamental building blocks and smallest identifiable units of elements.

Molecules

Well-defined chemical structures composed of two or more atoms bonded together in specific geometric arrangements.

Solid

A state of matter characterized by atoms or molecules packed closely together in fixed locations that vibrate or oscillate without moving past one another, yielding a definite shape and volume.

Liquid

A state of matter in which atoms or molecules are packed closely together but are free to move relative to one another, resulting in an indefinite shape that takes the container's form but a definite volume.

Gas

A state of matter composed of atoms or molecules separated by large distances and free to move independently, causing it to be compressible and expand to fill both the shape and volume of its container.

Crystalline Solid

A solid in which atoms or molecules occupy specific, well-ordered positions forming a three-dimensional lattice with long-range, repeating geometric order.

Amorphous Solid

A solid whose constituent atoms or molecules do not possess long-range order or regular geometric arrangement.

Pure Substance

A category of matter composed of only one kind of atom or molecule with an invariant composition throughout.

Mixture

A category of matter composed of two or more different substances that are physically combined in variable proportions rather than chemically united.

Element

A pure substance that cannot be broken down or decomposed into simpler substances by any chemical transformation.

Compound

A pure substance composed of two or more elements chemically united and bonded in fixed, definite proportions.

Heterogeneous Mixture

A mixture whose composition varies from one region to another, frequently forming distinct layers or phases.

Homogeneous Mixture

A mixture exhibiting a completely uniform composition and visual appearance throughout.

Physical Property

A characteristic that a substance displays without undergoing a change in its chemical composition.

Chemical Property

A characteristic that a substance displays only by changing its chemical composition through a chemical reaction.

Physical Change

A process that alters the appearance or state of matter without changing its underlying chemical composition.

Chemical Change

A process in which matter undergoes a chemical reaction that changes its chemical composition, producing completely new substances.

Reactants

The starting substances present prior to a chemical change in a chemical reaction.

Products

The resulting substances present after a chemical change in a chemical reaction.

Distillation

A physical separation process used for liquid mixtures with different boiling points, in which the most volatile component vaporizes first, and the vapor is subsequently condensed and collected as a pure liquid.

Filtration

A physical separation technique in which a mixture of a solid and a liquid is poured through filter paper, trapping the solid while allowing the liquid component to pass through.

Law of Conservation of Mass

The fundamental principle stating that matter is neither created nor destroyed during ordinary physical and chemical changes, requiring the total mass of the reactants to equal the total mass of the products.

Energy

A fundamental entity of the universe defined as the capacity to do work.

Work

The physical result of a force acting through a distance.

Law of Conservation of Energy

The physical law stating that energy is neither created nor destroyed, maintaining a constant total quantity in the universe while transferring between objects or converting between forms.

Kinetic Energy

The form of energy associated with the motion of an object or particle.

Potential Energy

The form of energy associated with the position or internal composition of an object or system.

Thermal Energy

The form of kinetic energy associated with the constant random motions of the atoms and molecules that compose matter.

Electrical Energy

The form of kinetic energy associated with the flow of electrical charge.

Chemical Energy

A form of potential energy stored in the relative positions and electrostatic arrangements of the chemical particles that compose a substance.

Joule

The SI unit of energy (symbol $\text{J}$), named after James Joule.

Calorie (cal)

A non-SI unit of energy defined as the amount of heat required to raise the temperature of $1\,\text{g}$ of water by $1\,^\circ\text{C}$, exactly equal to $4.184\,\text{J}$.

Nutritional Calorie (Cal)

An energy unit used in nutrition, equivalent to $1000\,\text{cal}$ or $1\,\text{kcal}$.

Kilowatt-Hour

A large commercial unit of electrical energy (symbol $\text{kWh}$), exactly equal to $3.60 \times 10^6\,\text{J}$.

Exothermic Reaction

A chemical reaction that releases energy to its surroundings.

Endothermic Reaction

A chemical reaction that absorbs energy from its surroundings.

Temperature

A quantitative measure of the average thermal energy and random molecular motion present in a substance.

Heat

The transfer or exchange of thermal energy between systems caused specifically by a temperature difference.

Absolute Zero

The coldest theoretical temperature possible, assigned the value $0\,\text{K}$ ($-273.15\,^\circ\text{C}$ or $-459\,^\circ\text{F}$), at which all molecular motion virtually stops.

Specific Heat Capacity

The quantity of heat required to change the temperature of $1\,\text{g}$ of a substance by $1\,^\circ\text{C}$, expressed in units of $\text{J}/(\text{g}\cdot^\circ\text{C})$.

Dalton's Atomic Theory

The atomic framework formalized in 1808 by John Dalton stating that: each element is composed of tiny, indestructible atoms; all atoms of a given element have the same mass and distinguishing properties; and atoms combine in simple whole-number ratios to form compounds.

Electron

A subatomic particle discovered by J. J. Thomson that possesses a negative electrical charge ($1-$) and an extremely small mass of $0.00091 \times 10^{-27}\,\text{kg}$ ($0.00055\,\text{amu}$).

Plum-Pudding Model

An early atomic model proposed by J. J. Thomson picturing negatively charged electrons embedded within a uniform sphere of positive charge.

Rutherford's Gold Foil Experiment

A 1909 experiment in which alpha particles were directed at an ultrathin sheet of gold foil; the deflection of a small fraction of particles revealed that the atom has a concentrated central nucleus.

Nucleus

The tiny, extremely dense central core of an atom that contains all of its positive charge and more than $99.9\%$ of its total mass.

Nuclear Theory of the Atom

Ernest Rutherford's atomic model establishing that an atom's mass and positive charge are concentrated in a central nucleus, with tiny electrons occupying a large surrounding volume of mostly empty space.

Proton

A subatomic nuclear particle possessing a positive charge ($1+$) and a mass of approximately $1.67262 \times 10^{-27}\,\text{kg}$ ($1.0073\,\text{amu}$).

Neutron

An uncharged (neutral) subatomic nuclear particle with a mass of approximately $1.67493 \times 10^{-27}\,\text{kg}$ ($1.0087\,\text{amu}$).

Atomic Number

The number of protons found within the nucleus of an atom (symbol $Z$), which defines the identity of a chemical element.

Periodic Law

The observation summarized by Dmitri Mendeleev stating that when elements are arranged in order of increasing relative mass, similar chemical and physical properties recur in a regular, repeating pattern.

Metals

Elements positioned on the left and center of the periodic table that are good conductors of heat and electricity, malleable, ductile, lustrous, and tend to lose electrons in chemical reactions.

Nonmetals

Elements situated on the upper right side of the periodic table that tend to be poor conductors of heat and electricity and tend to gain electrons during chemical reactions.

Metalloids

Elements situated along the zigzag diagonal dividing line of the periodic table that display intermediate properties and controllable electrical conductivity, functioning as semiconductors.

Alkali Metals

A family of highly reactive metallic elements in Group 1A of the periodic table, consisting of lithium, sodium, potassium, rubidium, and cesium (excluding hydrogen).

Alkaline Earth Metals

A family of fairly reactive metals in Group 2A of the periodic table, consisting of beryllium, magnesium, calcium, strontium, and barium.

Halogens

A family of very reactive nonmetals located in Group 7A of the periodic table, including fluorine, chlorine, bromine, iodine, and astatine.

Noble Gases

A family of chemically inert, stable gaseous elements found in Group 8A of the periodic table, including helium, neon, argon, krypton, and xenon.

Ion

An atom or group of atoms that has acquired an electrical charge by losing or gaining electrons.

Cation

A positively charged ion formed when a neutral atom loses one or more electrons.

Anion

A negatively charged ion formed when a neutral atom gains one or more electrons.

Isotopes

Atoms of the same element having identical numbers of protons but differing numbers of neutrons.

Mass Number

The total integer sum of the number of protons and neutrons located in an atom's nucleus (symbol $A$).

Atomic Mass

The weighted average mass of the naturally occurring isotopes of an element, calculated using their fractional abundances and respective isotopic masses.

Radioactive Isotopes

Unstable isotopes whose nuclei decay spontaneously, emitting energetic subatomic particles known as nuclear radiation.