Honors Chemistry Unit 1: Matter, Change, Atomic Theory, and Isotopes

Vocabulary practice flashcards covering atomic theory, subatomic particles, isotopes, average atomic mass, states of matter, physical and chemical properties, and separation techniques.

Extensive Property

A property of matter that depends on the amount of matter in a sample, such as mass, volume, and calories.

Intensive Property

A property of matter that depends on the type of matter in a sample, not the amount, such as hardness, density, and boiling point.

Density

The ratio of the mass of an object to its volume, calculated as $\text{D} = \frac{m}{v}$.

Physical Property

A quality or condition of a substance that can be observed or measured without changing the substance's composition, such as color, hardness, melting point, boiling point, and density.

Chemical Property

The ability of a substance to undergo a specific chemical change, such as the ability to burn, decompose, ferment, or react with other substances.

Homogeneous Mixture

A mixture in which the composition is uniform throughout, also known as a solution (e.g., air, sugar in water, stainless steel).

Heterogeneous Mixture

A mixture in which the composition is not uniform throughout, where every part retains its own properties (e.g., granite, wood, blood).

Pure Substance

Matter that has a uniform and definite composition, classified as either an element or a compound.

Element

A pure substance that cannot be decomposed by ordinary chemical means, represented by a one- or two-letter symbol (e.g., Gold, aluminum, oxygen, chlorine).

Compound

A pure substance that can be decomposed by ordinary chemical means, represented by a chemical formula (e.g., water, $\text{NaCl}$, sucrose).

Physical Change

A change that alters some properties of a material without changing its chemical composition, such as boiling, melting, cutting, bending, splitting, or cracking.

Chemical Change

A change that produces matter with a different composition than the original matter, such as rusting, burning, decomposing, or fermenting.

Signs of a Chemical Change

Indicators that a chemical change has occurred, including liquid formation - energy, color change, gas formation (bubbles), solid formation (precipitate), and irreversibility.

Law of Conservation of Mass

The fundamental principle stating that mass is conserved and cannot be created or destroyed during physical or chemical changes.

Filtration

A physical separation technique used to separate solid components from liquids in a heterogeneous mixture.

Distillation

A physical separation technique that separates components of a liquid mixture by taking advantage of differences in their boiling points.

Paper Chromatography

A physical separation technique used to separate the components of dyes or ink.

Copper Phase Temperatures

Copper exists as a solid at temperatures $\le 1083^\circ\text{C}$, as a liquid between $1083^\circ\text{C}$ and $2594^\circ\text{C}$, and as a vapor (gas) at temperatures $\ge 2595^\circ\text{C}$.

Isotopes

Atoms of the same element that have the same number of protons but differ in their number of neutrons.

Average Atomic Mass

The weighted average mass of all naturally occurring isotopes of an element, based on their relative percentage abundance and measured in atomic mass units ($\text{amu}$).

Calculation of Average Atomic Mass

Determined by multiplying the atomic mass of each isotope by its fractional abundance (percent divided by 100), and then summing the results.

Carbon-12 ($^{12}\text{C}$)

The most abundant isotope of carbon ($98.89\%$ abundance), composed of 6 protons and 6 neutrons in its nucleus.

Carbon-13 ($^{13}\text{C}$)

An isotope of carbon with a natural abundance of $1.11\%$ comprised of 6 protons and 7 neutrons in its nucleus.

Carbon-14 ($^{14}\text{C}$)

An isotope of carbon with a natural abundance of $<0.01\%$ comprised of 6 protons and 8 neutrons in its nucleus.

Atomic Number

The number of protons in an atom, which uniquely determines the identity of an element.

Mass Number

The combined total number of protons and neutrons located in the nucleus of an atom.

Neutral Atom

An atom in which the number of negatively charged electrons is equal to the number of positively charged protons.

Democritius

The ancient philosopher who first suggested the existence of fundamental, indivisible particles called atoms.

John Dalton

The scientist who formulated an early atomic theory, incorrectly stating that all atoms of the same element are completely identical.

J.J. Thompson

The scientist who discovered the electron using cathode rays and proposed the plum pudding atomic model.

Ernest Rutherford

The scientist who conducted the gold foil experiment, discovering the dense, positively charged atomic nucleus.

Niels Bohr

The scientist who created the Bohr model of the atom, depicting electrons orbiting the nucleus in specific fixed energy levels.

Erwin Schrodinger

The scientist who developed the quantum mechanical model of the atom, describing electrons in terms of mathematical probability clouds rather than rigid orbits.

Discovery of the Neutron

The discovery of the neutral subatomic particle located in the nucleus, which led to a clearer understanding of isotopes and atomic mass variations.