Chem Chapter1-6

Chemistry

The science that investigates the materials of the universe, their structure and properties, and the changes of matter and energy they undergo.

Organic chemistry

The branch of chemistry that deals with carbon-containing compounds, excluding carbonates, oxides, and carbides.

Inorganic chemistry

The branch of chemistry that deals with all elements and their compounds, excluding organic compounds.

Physical chemistry

The branch of chemistry that applies the laws and theories of physics to understand the structure, properties, and changes of matter.

Analytical chemistry

The branch of chemistry focused on instruments and methods used to separate, identify, and quantify the components of matter.

Biochemistry

The branch of chemistry that investigates the physical and chemical processes occurring within living organisms.

Environmental chemistry

The branch of chemistry that studies chemical and toxic pollutants in the environment and their effects on human health and ecosystems.

Industrial chemistry

The branch of chemistry concerned with the large-scale manufacturing and processing of chemical substances.

Medicinal chemistry

The branch of chemistry that examines interactions between drugs and biological targets to develop new therapeutic agents.

Polymer chemistry

The branch of chemistry that focuses on the synthesis, properties, and structural applications of macromolecular chains.

Nuclear chemistry

The branch of chemistry that deals with changes, reactions, and properties occurring within atomic nuclei.

Astrochemistry

The branch of chemistry that studies chemical compositions and reactions occurring in astronomical environments such as stars and interstellar space.

Green chemistry

The design of chemical products and processes that minimize or eliminate the generation and use of hazardous substances.

Technology

The process of applying scientific knowledge to create practical machines, materials, and systems that solve problems.

Engineering

The practical discipline that uses science and mathematics to design, construct, and optimize structures, machines, and manufacturing processes.

Matter

Anything that possesses mass and occupies physical space.

Plasma

An ionized, high-energy state of matter composed of positive ions and free electrons that responds to electric and magnetic fields.

Bose-Einstein Condensate

A state of matter occurring when separate atoms are cooled to near absolute zero, causing them to coalesce into a single quantum mechanical entity.

Allotropy

The ability of an element to exist in two or more distinct physical forms having different structural arrangements in the same state.

Graphite structure and properties

Flat two-dimensional layers of hexagonal carbon rings held by weak forces, making it soft, slippery, and electrically conductive.

Diamond structure and properties

A rigid three-dimensional tetrahedral network where each carbon atom is covalently bonded to four others, resulting in extreme hardness and electrical insulation.

Buckyballs ($C_{60}$)

Spherical allotropes of carbon featuring a hollow cage formed by twenty hexagons and twelve pentagons.

Saturated solution

A mixture containing the maximum dissolved solute at a given temperature in dynamic equilibrium with undissolved solute.

Supersaturated solution

An unstable mixture that contains a greater concentration of dissolved solute than required for complete saturation at that temperature.

Colloid

A heterogeneous mixture with particle sizes between $1\,\text{nm}$ and $1000\,\text{nm}$ that stay suspended without settling and scatter light.

Suspension

A heterogeneous mixture containing insoluble particles larger than $1000\,\text{nm}$ that remain dispersed temporarily before settling upon standing.

Tyndall effect

The scattering of visible light beams as they pass through a colloidal dispersion, making the light path visible.

Rutherford's alpha scattering experiment

Bombarding thin gold foil with doubly charged helium nuclei ($\text{He}^{2+}$), revealing that atoms are mostly empty space with a dense, positively charged nucleus.

Bohr's atomic model

A planetary theory proposing that electrons orbit the nucleus in fixed, quantized circular energy levels without radiating energy unless transitioning between levels.

Heisenberg uncertainty principle

The quantum concept stating that it is fundamentally impossible to simultaneously determine both the exact position and momentum of an electron.

Strong nuclear force

A powerful attractive fundamental force operating at short range that overcomes electrostatic repulsion to bind protons and neutrons together in the nucleus.

Atomic number ($Z$)

The total number of protons located in the nucleus of an atom, defining its elemental identity.

Mass number ($A$)

The total sum of protons and neutrons (nucleons) present in an atom's nucleus.

Isotopes

Atoms of the same element containing identical numbers of protons but differing numbers of neutrons, resulting in different mass numbers.

Carbon dating

An archaeological technique that determines the age of carbon-containing specimens by measuring the radioactive decay ratio of $\text{C}-14$ to $\text{C}-12$.

Cation

A positively charged ion formed when a neutral atom, typically a metal, loses one or more valence electrons.

Anion

A negatively charged ion formed when a neutral atom, typically a non-metal, gains one or more valence electrons.

Aufbau principle

The rule stating that electrons fill available subshells in order of increasing energy, occupying the lowest energy subshell first.

Modern periodic law

The principle stating that the physical and chemical properties of elements recur periodically when arranged in order of increasing atomic number.

Shielding effect

The reduction in nuclear electrostatic attraction experienced by outer valence electrons due to the presence of intervening inner-shell electrons.

Atomic radius periodic trend

The measure of atomic size that decreases across a period due to increasing nuclear charge, and increases down a group as new electron shells are added.

Ionization energy

The minimum energy required to remove the most loosely held valence electron from an isolated gaseous atom: $M(g) + \text{energy} \rightarrow M^+(g) + e^-$.

Electron affinity

The quantity of energy released when an electron is added to the valence shell of an isolated neutral gaseous atom to produce a uninegative anion.

Electronegativity

The relative ability of an atom bonded in a molecule to attract shared electron pairs toward itself.

Properties of alkali metals (Group 1)

Highly reactive, soft metals with low densities and melting points that possess one valence electron ($ns^1$) and react vigorously with water to form basic hydroxides and hydrogen gas.

Properties of halogens (Group 17)

Reactive diatomic non-metals ($ns^2\,np^5$) whose physical states transition from pale yellow gas ($F_2$) to yellow-green gas ($Cl_2$), red-brown liquid ($Br_2$), and grey-black solid ($I_2$).

Transition elements

d-block metals characterized by high densities, elevated melting points, variable oxidation states, catalytic activity, and the formation of colored complex ions.

Noble gases (Group 18)

Chemically inert, colorless, monoatomic gases possessing completely filled outermost electron shells ($ns^2\,np^6$), making them exceptionally stable.

Octet rule

The principle that main-group atoms tend to bond, gain, lose, or share electrons until they achieve a stable outer shell containing eight electrons.

Duplet rule

The tendency of small atoms such as hydrogen and lithium to achieve stability by completing their outermost valence shell with two electrons, mimicking helium.

Ionic bond

The strong electrostatic force of attraction between oppositely charged cations and anions formed by complete electron transfer.

Covalent bond

A chemical linkage formed through the mutual sharing of one or more electron pairs between two atoms, electrostatic in origin between shared electrons and both nuclei.

Coordinate covalent bond (Dative bond)

A covalent linkage in which both shared electrons in the bonding pair originate exclusively from a single donor atom possessing a lone pair.

Hydrogen bonding

An intermolecular attraction occurring between a highly electron-deficient hydrogen atom covalently bonded to nitrogen, oxygen, or fluorine and an electronegative atom's lone pair.

Metallic bond

The electrostatic attraction between a regular lattice of positively charged metal ions and a surrounding mobile sea of delocalized valence electrons.

Empirical formula

The simplest whole-number ratio of the different atoms present in a chemical compound.

Molecular formula

The chemical formula indicating the actual number of atoms of each constituent element present in a single molecule of a compound.

Mole

The amount of substance that contains exactly $6.022 \times 10^{23}$ representative elementary particles (atoms, molecules, or formula units).

Avogadro's number ($N_A$)

The fundamental constant representing the number of constituent particles in one mole of any substance, equal to $6.022 \times 10^{23}\,\text{particles}$.

Spectator ions

Ions that remain unchanged in solution on both sides of a chemical equation and do not directly participate in the chemical reaction.