General Chemistry: Matter, Atomic Theory, and Dimensional Analysis

Vocabulary flashcards covering fundamental chemistry concepts, states of matter, atomic theory development, subatomic particles, atomic notation, and dimensional analysis based on lecture notes.

Matter

Anything that occupies space and has mass.

Substance

A form of matter that has a definite composition and distinct properties.

Chemistry

The study of matter and the changes it undergoes.

Three States of Matter

The three physical forms of matter: solid (rigid with definite shape and volume), liquid (fixed volume but assumes container shape), and gas (no fixed shape or volume).

Physical Change

A change that does not alter the composition or identity of a substance, such as ice melting or sugar dissolving in water.

Chemical Change

A change that alters the composition or identity of the substance(s) involved, such as hydrogen burning in air to form water.

Element

A substance that cannot be separated into simpler substances by chemical means.

Compound

A substance composed of atoms of two or more elements chemically united in fixed proportions, separable into its pure components only by chemical means.

Mixture

A combination of two or more substances in which the individual substances retain their distinct identities.

Homogeneous Mixture

A mixture in which the composition is the same throughout, such as milk, solder, or a soft drink.

Heterogeneous Mixture

A mixture in which the composition is not uniform throughout, such as cement or iron filings in sand.

Classifications of Matter

A hierarchical framework categorizing matter into mixtures (homogeneous/heterogeneous) separated physically, and pure substances (compounds/elements) separated chemically.

Extensive Property

A property of a material that depends upon how much matter is being considered, such as mass, length, or volume.

Intensive Property

A property of a material that does not depend upon how much matter is being considered, such as density, temperature, or color.

Dalton's Atomic Theory

A theory proposed in 1808 stating that elements consist of atoms, atoms of an element are identical, compounds consist of combined elements in whole-number/fractional ratios, and reactions rearrange atoms.

Law of Multiple Proportions

The law demonstrating that different compounds formed from the same elements combine in fixed simple whole-number ratios of atoms (e.g., carbon monoxide $\text{O/C} = 1/1$ vs carbon dioxide $\text{O/C} = 2/1$).

Law of Conservation of Mass

The law stating that matter can neither be created nor destroyed in a chemical reaction; the rearrangement of atoms maintains total mass (e.g., $16\,\text{X} + 8\,\text{Y} \rightarrow 8\,\text{X}_2\text{Y}$).

Thomson's Model

An early atomic model proposing that an atom consists of a sphere of positive charge with negatively charged electrons embedded throughout.

Cathode Ray Tube Experiment

An experiment conducted by J.J. Thomson used to measure the mass-to-charge ratio of the electron ($e^-$), earning him the 1906 Nobel Prize in Physics.

Rutherford's Experiment

An experiment directing high-velocity $\alpha$ particles at gold foil, establishing that an atom's positive charge and mass are concentrated in a central nucleus.

Millikan's Experiment

An oil drop experiment determining the charge of an electron ($e^- charge = -1.60 \times 10^{-19}\,\text{C}$) and its mass ($e^- mass = 9.10 \times 10^{-28}\,\text{g}$), earning the 1923 Nobel Prize in Physics.

Electron

A negatively charged subatomic particle with a mass of $9.10938 \times 10^{-28}\,\text{g}$, a Coulomb charge of $-1.6022 \times 10^{-19}\,\text{C}$, and a charge unit of $-1$.

Proton

A positively charged subatomic particle found in the nucleus with a mass of $1.67262 \times 10^{-24}\,\text{g}$, a Coulomb charge of $+1.6022 \times 10^{-19}\,\text{C}$, and a charge unit of $+1$.

Neutron

A neutral subatomic particle discovered by Chadwick in 1932 with a charge of $0$ and a mass of $1.67493 \times 10^{-24}\,\text{g}$, approximately equal to the mass of a proton.

Atomic Radius vs Nuclear Radius

The comparison showing that an atom's overall radius is $\sim 100\,\text{pm}$ ($1 \times 10^{-10}\,\text{m}$), whereas its nuclear radius is only $\sim 5 \times 10^{-3}\,\text{pm}$ ($5 \times 10^{-15}\,\text{m}$).

Atomic Number

Represented by $Z$, it is the total number of protons present in the nucleus of an atom.

Mass Number

Represented by $A$, it is the total number of protons plus neutrons present in the nucleus of an atom ($A = Z + \text{number of neutrons}$).

Isotopes

Atoms of the same element ($X$) that have the same atomic number ($Z$) but different mass numbers ($A$) due to varying numbers of neutrons.

Dimensional Analysis

A problem-solving method using unit conversion factors to ensure unwanted units cancel out and leave only the desired unit in the final answer.