General Chemistry Fundamentals

Vocabulary flashcards generated from lecture transcript on fundamental chemistry concepts, SI units, atomic structure, periodic table properties, and chemical formulas.

Matter

Anything that has mass and occupies space/volume.

Pure Substance

A sample of matter that cannot be separated into other kinds of matter by physical means.

Mixture

A sample of matter that can be separated into two or more substances by physical means.

Homogeneous Mixture

A mixture that is uniform in composition throughout (e.g., salt water).

Heterogeneous Mixture

A mixture that is not uniform throughout; different parts have different compositions (e.g., oil and water).

Element

A substance that cannot be decomposed into simpler substances by a chemical process.

Compound

A substance composed of two or more elements chemically combined in fixed proportion, which CAN be decomposed by a chemical process.

Physical Property

A property observed without changing the substance's chemical identity (e.g., color, density, melting point).

Chemical Property

A property describing how a substance reacts to form a new substance (e.g., flammability, reactivity with acid).

Physical Change

A change that does not alter the chemical composition of a substance (e.g., melting, freezing, dissolving).

Chemical Change

A change that produces one or more new substances with different chemical composition.

Extensive Properties

Properties that depend on (increase with) the amount/size of the system, e.g., mass, volume, length, area.

Intensive Properties

Properties that are independent of the amount/size of the system, e.g., density, temperature, specific heat capacity, color.

SI

Système Internationale d'Unités (International System of Units).

Density

The ratio of mass to volume, defined as $\text{density } (d) = \frac{\text{mass } (m)}{\text{volume } (V)}$.

Water Displacement Method

A method to find the volume/density of an irregularly shaped object by submerging it in water; the volume of water displaced equals the object's volume.

Random Error

Error from intrinsic instrument fluctuations, reading errors, etc., varying unpredictably between measurements.

Systematic Error

Error that recurs regularly throughout a series of measurements due to an inherent flaw in the measuring system (e.g., calibration error).

Accuracy

Closeness of a measurement to the true value.

Precision

Reproducibility of repeated measurements (how close they are to each other).

Law of Conservation of Mass

Mass is neither created nor destroyed in a chemical reaction; the total mass of reactants equals the total mass of products.

Law of Constant Composition

A given compound always contains the same elements in the exact same proportion by mass, regardless of the sample's source or size.

Law of Multiple Proportions

When two elements form more than one compound, the masses of one element that combine with a fixed mass of the other are in a ratio of small whole numbers.

Cathode Ray Tube (CRT) Experiment

An experiment used by J.J. Thomson to demonstrate the existence of the electron by showing cathode rays are deflected by electric and magnetic fields.

Oil Drop Experiment

An experiment by Robert Millikan that determined the precise charge of a single electron, allowing calculation of the electron's mass.

Gold Foil Experiment

An experiment by Rutherford revealing that the atom has a small, dense, positively charged nucleus, with most of the atom being empty space.

Atomic Number ($Z$)

The number of protons in the nucleus of an atom; it defines which element the atom is.

Mass Number ($A$)

The total number of protons plus neutrons in the nucleus of an atom.

Nuclide

The general term for an atom with a particular number of protons, neutrons, and electrons.

Isotopes

Atoms of the same element (same number of protons/atomic number) that have different numbers of neutrons (different mass numbers).

Atomic Mass Unit (amu)

Defined as exactly $\frac{1}{12}$ the mass of a carbon-12 ($^{12}\text{C}$) atom.

Average Atomic Mass

The weighted average of the masses of all naturally occurring isotopes of an element, weighted by their relative percentage abundance.

Groups

The vertical columns on the periodic table; elements in the same group have similar chemical and physical properties.

Periods

The horizontal rows on the periodic table; each period shows a pattern of properties that repeats in the next period.

Alkali Metals

Group 1 (IA) elements: Li, Na, K, Rb, Cs, Fr.

Alkaline Earth Metals

Group 2 (IIA) elements: Be, Mg, Ca, Sr, Ba, Ra.

Halogens

Group 17 (VIIA) elements ('salt formers'): F, Cl, Br, I, At.

Noble Gases

Group 18 (VIIIA) elements: He, Ne, Ar, Kr, Xe, Rn.

Chalcogens

Group 16 (VIA) elements ('ore formers'): O, S, Se, Te, Po.

Pnictogens

Group 15 (VA) elements ('choke, stifle'): N, P, As, Sb, Bi.

Transition Metals

Elements in groups 3–12, occupying the middle d-block of the periodic table.

Metalloids

Elements with properties of both metals and nonmetals, forming a step-like region between them: B, Si, Ge, As, Sb, Te, Po.

Avogadro's Number

The defined value $6.02214179 \times 10^{23}\,\text{mol}^{-1}$ (often rounded to $6.022 \times 10^{23}$); the number of particles in one mole.

Mole

The SI unit for 'amount of substance'; one mole contains exactly Avogadro's number ($6.022 \times 10^{23}$) of particles.

Molar Mass

The mass in grams of one mole of a substance (numerically equal to the atomic/molecular mass in amu).

Covalent Bond

A bond in which electrons are shared between atoms, prevalent between nonmetal atoms.

Ionic Bond

An electrostatic attraction between oppositely charged ions, formed when one atom transfers an electron to another.

Bond Length

The distance between the nuclei of two bonded atoms, equal to the sum of their atomic/covalent radii ($r_1 + r_2$).

Molecular Formula

A chemical formula showing the types and numbers of atoms in a molecule, but not the structural arrangement.

Structural Formula

A chemical formula that shows how atoms are connected/arranged within a molecule, including bonds between atoms.

Formula Unit

The smallest electrically neutral collection of ions that represents the ratio of ions in an ionic compound.

Crystal Lattice

The massive 3D repeating pattern of ions (or atoms) in an ionic (or other) crystalline solid.

Unit Cell

The smallest repeating box/unit that, repeated in 3D, builds the entire crystal lattice pattern.

Fajans' Rule

A rule describing the degree of covalent character in an ionic bond based on factors like ion charge and size.

Combustion Analysis

A technique used for determining the empirical formula of a compound by measuring the $\text{CO}_2$ and $\text{H}_2\text{O}$ produced when the compound is burned.

Oxidation State

A number assigned to an atom representing the hypothetical charge it would have if all bonds were fully ionic.

Hydrate

An ionic compound that has a specific number of water molecules associated with each formula unit.

Organic Chemistry

The branch of chemistry dealing with carbon-based (hydrocarbon-containing) compounds.

Functional Group

A specific group of atoms within a molecule responsible for characteristic chemical reactions of that molecule.

Hydrocarbons

Organic compounds composed of only carbon and hydrogen atoms.

Alkane

A saturated hydrocarbon containing only single bonds between carbon atoms, with general formula $\text{C}_n\text{H}_{2n+2}$.

Isomers

Compounds with the same molecular formula but different structural arrangements of atoms.