Madrid PAU General Sciences - independent foundations key terms

The number of protons in the nucleus of an atom, which uniquely identifies the element. In a neutral atom it also equals the number of electrons.

The total count of protons plus neutrons in one atom's nucleus. It is a whole number written as a superscript beside the element symbol and differs between isotopes.

One of two or more atoms of the same element that have equal proton counts but different neutron counts, so they differ in mass while sharing nearly identical chemical behaviour.

The weighted average mass of an element's atoms compared with one-twelfth the mass of a carbon-12 atom, taking natural isotopic abundance into account. It is dimensionless and rarely a whole number.

The rule that electrons occupy the lowest-energy available orbitals first when an atom is built up, giving the familiar 1s 2s 2p 3s filling order and the ground-state configuration.

The arrangement of an atom's electrons among its shells, subshells and orbitals, usually written with superscripts such as 1s2 2s2 2p6. It governs chemical behaviour and position in the periodic table.

The statement that electrons fill degenerate orbitals singly, with parallel spins, before any pairing occurs. It explains the unpaired electrons in nitrogen and the paramagnetism of many transition-metal ions.

A force directed toward equilibrium, often proportional to displacement over an explicitly specified linear range; its direction determines the sign in the oscillator equation.

The angular frequency of free oscillation in the chosen ideal model, measured in radians per second and related to period by omega = two pi divided by period.

Transfer of oscillator energy to other forms through mechanisms such as friction or electrical resistance, changing amplitude and potentially the observed response frequency.

The fraction of incident radiant energy reflected by a surface or planetary system, defined for a specified spectral and averaging context.

Accounting for incoming sunlight, reflected sunlight and emitted thermal radiation across the planetary outer boundary; an imbalance represents energy accumulation or loss.

A response to a perturbation that changes energy flows and thereby amplifies or reduces the initial temperature response, depending on the process and sign.

Small, single units that join end to end in long chains, such as amino acids forming proteins or nucleotides forming nucleic acids. Their structure determines the properties of the polymer built from them.

A large molecule made of many similar subunits linked in sequence, such as starch from glucose or a protein from amino acids. Its behaviour depends on chain length, branching and folding.

A joining reaction in which two molecules bond and a small molecule, usually water, is released. It builds glycosidic, peptide and ester bonds when smaller units are assembled into larger biological molecules.

A splitting reaction in which a water molecule is used to break a bond between subunits. Digestion of starch, proteins and lipids depends on it, and it reverses condensation.

The bond formed between the hydroxyl groups of two monosaccharides with the loss of water. Its orientation, alpha or beta, changes whether a polysaccharide coils or forms straight strands.

A storage polysaccharide of alpha-glucose found in plant cells, made of amylose and amylopectin. It is compact, insoluble and easily hydrolysed to release glucose for respiration.

A structural beta-glucose polysaccharide forming straight chains associated into strong plant-wall microfibrils. Most animals lack their own cellulase enzymes, while some obtain cellulose digestion through symbiotic microorganisms.

A sugar with a free carbonyl group able to donate electrons, so it reduces copper(II) ions to a brick-red precipitate when heated in Benedict's reagent. All monosaccharides and most disaccharides qualify.

The covalent link formed between the amino group of one amino acid and the carboxyl group of another, releasing water. It is rigid and planar, which constrains how a polypeptide chain can fold.

The exact sequence of amino acids in a polypeptide, held by peptide bonds. It is coded by DNA and ultimately determines the three-dimensional shape and function of the protein.

Estado de equilibrio gravitatorio de masas litosféricas respecto al material subyacente, interpretado mediante diferencias de espesor y densidad sin exigir un océano de magma.

Superficie interna donde la velocidad de las ondas sísmicas cambia bruscamente, delimitando capas terrestres; las principales son Mohorovičić, Gutenberg y Lehmann.

Discontinuidad de Mohorovičić, límite entre la corteza y el manto donde las ondas P aceleran de forma brusca; su profundidad varía entre unos 5 y 70 km.

Ondas elásticas generadas por un terremoto: las P son longitudinales y atraviesan sólidos y fluidos; las S son transversales y no se propagan por líquidos.

Región central de la Tierra, dividida en núcleo interno sólido y externo líquido, compuesta mayoritariamente por hierro y níquel; genera el campo magnético terrestre.

Región entre corteza y núcleo, compuesta principalmente por rocas silicatadas y mayoritariamente sólida; puede deformarse y transportar calor en escalas geológicas.

Capa externa rígida de la Tierra formada por la corteza y la parte superior del manto; está fragmentada en placas que se desplazan sobre la astenosfera.