Slovakia Maturita Chemistry key terms

The number of protons in the nucleus of an atom, which uniquely identifies the element and determines its position in the periodic table.

The total number of protons and neutrons in an atomic nucleus, written as a superscript before the element symbol.

Atoms of the same element that have the same number of protons but different numbers of neutrons, giving them different mass numbers.

The arrangement of electrons in an atom's energy levels and orbitals, usually written using the aufbau principle and notation such as 1s² 2s² 2p⁶.

An electron in the outermost shell of an atom that participates in chemical bonding and largely determines the element's chemical properties.

A tabular arrangement of elements ordered by increasing atomic number, with groups (columns) and periods (rows) reflecting recurring chemical properties.

A measure of how strongly an atom attracts shared electrons in a chemical bond; it generally increases across a period and decreases down a group.

The electrostatic attraction between oppositely charged ions, formed when one atom transfers electrons to another, typically between a metal and a nonmetal.

A chemical bond formed by the sharing of one or more pairs of electrons between two atoms, common between nonmetal atoms.

A covalent bond in which electrons are shared unequally because the bonded atoms have different electronegativities, creating partial charges.

The SI unit for amount of substance, defined as containing exactly 6.022 × 10²³ elementary entities (Avogadro's number).

The mass of one mole of a substance, expressed in grams per mole (g/mol), numerically equal to its relative molecular mass.

The number of particles (atoms, molecules, ions) in one mole of a substance, approximately 6.022 × 10²³ mol⁻¹.

The quantitative relationship between amounts of reactants and products in a balanced chemical equation, used to calculate masses, moles, or volumes.

The reactant that is completely consumed first in a chemical reaction and therefore determines the maximum amount of product that can form.

The amount of product actually obtained in a chemical reaction, often expressed as a percentage of the theoretical maximum calculated from stoichiometry.

A chemical process in which an atom, ion, or molecule loses electrons, corresponding to an increase in oxidation state.

A chemical process in which an atom, ion, or molecule gains electrons, corresponding to a decrease in oxidation state.

A reaction involving the transfer of electrons from one species to another, consisting of simultaneous oxidation and reduction half-reactions.

A logarithmic scale (0–14) measuring the acidity or basicity of an aqueous solution, defined as the negative logarithm of hydrogen ion concentration.

A substance that donates protons (H⁺ ions) in aqueous solution (Brønsted–Lowry) or accepts an electron pair (Lewis), producing a pH below 7.

A substance that accepts protons (H⁺ ions) in aqueous solution (Brønsted–Lowry) or donates an electron pair (Lewis), producing a pH above 7.

A reaction between an acid and a base that produces a salt and water, often accompanied by heat release.

A quantitative analytical technique in which a solution of known concentration is added gradually to a measured volume of another solution until the equivalence point is reached.

A weak acid or base that changes colour over a specific pH range, used to detect the endpoint of a titration.

A chemical reaction that releases energy to its surroundings, usually as heat, so the products have lower enthalpy than the reactants.

A chemical reaction that absorbs energy from its surroundings, so the products have higher enthalpy than the reactants.

A thermodynamic quantity representing the total heat content of a system at constant pressure; enthalpy change (ΔH) measures heat absorbed or released in a reaction.

The minimum energy that colliding particles must possess for a chemical reaction to occur; it acts as an energy barrier that catalysts lower.

A substance that increases the rate of a chemical reaction by lowering its activation energy without being consumed in the overall process.

A dynamic state in a reversible reaction where the forward and reverse reaction rates are equal, so the concentrations of reactants and products remain constant.

A rule stating that when a system at equilibrium is disturbed by a change in concentration, pressure, or temperature, the system shifts to counteract that change.

A saturated hydrocarbon containing only single carbon–carbon bonds, with the general formula CnH2n+2; examples include methane and ethane.

An unsaturated hydrocarbon containing at least one carbon–carbon double bond, with the general formula CnH2n; ethene is the simplest example.

An unsaturated hydrocarbon containing at least one carbon–carbon triple bond, with the general formula CnH2n−2; ethyne (acetylene) is the simplest example.

An atom or group of atoms within an organic molecule that determines its characteristic chemical properties and reactions, such as –OH, –COOH, or –NH2.

The systematic set of rules for naming chemical compounds, especially organic molecules, based on the longest carbon chain and its functional groups.

An organic compound containing a hydroxyl (–OH) group bonded to a saturated carbon atom; ethanol is a common example.

An organic compound containing the carboxyl group (–COOH), which makes it acidic; ethanoic acid (acetic acid) is a common example.

An organic compound formed by the reaction of a carboxylic acid with an alcohol, releasing water; esters often have pleasant fruity odours.

The acid-catalysed reaction between a carboxylic acid and an alcohol that produces an ester and water, typically reversible.

A large molecule made by linking many small repeating units (monomers) together, either naturally (e.g., proteins) or synthetically (e.g., polyethylene).

A small molecule that can join with many identical or similar molecules to form a polymer through polymerisation reactions.

A reaction in which two or more molecules combine to form a single product without the loss of any small molecule, typical of alkenes and alkynes.

A biomolecule made of carbon, hydrogen, and oxygen, including sugars, starches, and cellulose, serving as a primary energy source for living organisms.

A simple monosaccharide sugar with the formula C6H12O6, a key energy source in cells and a building block of starch and cellulose.

A large biomolecule composed of amino acids linked by peptide bonds, performing structural, catalytic, and regulatory functions in living organisms.

An organic molecule containing both an amino group (–NH2) and a carboxyl group (–COOH); it is the monomer from which proteins are built.

The covalent bond formed between the carboxyl group of one amino acid and the amino group of another, releasing water and linking amino acids in proteins.

A protein (or sometimes RNA) that acts as a biological catalyst, speeding up metabolic reactions by lowering activation energy with high specificity.

A diverse group of hydrophobic biomolecules including fats, oils, and steroids, important for energy storage, membrane structure, and signalling.

The metabolic pathway that breaks down glucose into pyruvate in the cytoplasm, producing a small amount of ATP and NADH without requiring oxygen.

Adenosine triphosphate, the universal energy-carrying molecule in cells; its hydrolysis releases energy used to drive many cellular processes.

The warming of Earth's surface caused by atmospheric gases such as carbon dioxide and methane trapping outgoing infrared radiation.

A non-renewable energy source formed from ancient organic matter, including coal, petroleum, and natural gas, whose combustion releases carbon dioxide.

The process of collecting and processing used materials such as paper, glass, and metals to make new products, reducing waste and resource consumption.

A separation technique that uses a porous barrier (filter paper) to separate a solid from a liquid or gas mixture based on particle size.

A separation method that boils a liquid mixture and condenses the vapour, separating components based on differences in boiling point.

An analytical technique that separates mixture components by distributing them between a stationary phase and a mobile phase, based on differing affinities.

A document that provides information about a chemical's hazards, safe handling, storage, and emergency measures, required in laboratories and workplaces.