Chemistry: Matter, Atoms, Changes, and Reactions

Vocabulary flashcards covering atomic theory, periodic table structure, elements, compounds, physical and chemical changes, reaction rates, and recycling processes based on lecture notes.

Atom

The fundamental unit of matter that cannot be divided further by simple means, originally derived from the Greek word atomos.

Dalton's Atomic Theory

A scientific theory proposed by John Dalton stating that all matter is composed of indivisible atoms of varying weights that combine to form substances.

Law of Octaves

An arrangement of elements published by John Newlands in 1865, grouping atoms into sets of eight with similar physical and chemical properties.

Periodic Table

A tabular arrangement of chemical elements ordered by atomic size and properties, organized into horizontal periods and vertical groups.

Periods

The horizontal rows of elements in the periodic table.

Groups

The vertical columns of elements in the periodic table that share similar chemical and physical properties.

Element

A pure substance made of only one type of atom that cannot be broken down into simpler substances.

Monatomic Element

An element consisting of single, unbonded atoms in its natural gas state, such as helium ($He$) or neon ($Ne$).

Diatomic Element

An element whose atoms naturally bond in pairs of two, such as oxygen ($O_2$), hydrogen ($H_2$), or nitrogen ($N_2$).

Molecule

A particle formed when two or more atoms are chemically linked or bonded together.

Molecular Element

A molecule consisting of two or more atoms of the same element bonded together, such as $O_2$.

Compound

A substance composed of two or more different types of elements chemically bonded together, such as water ($H_2O$) or carbon dioxide ($CO_2$).

Polymer

A complex compound composed of long repeating strings or chains of atomic groups, such as plastics, starch, or proteins.

Pure Substance

A material composed of only one type of particle, either a single element or a single compound, with consistent uniform properties.

Mixture

A combination of two or more different substances that are physically combined without chemical bonding.

Physical Change

An alteration in the appearance, shape, or state of matter where the underlying particles and molecules remain unchanged and no new substance is formed.

Vaporise

The physical process of a liquid evaporating or changing state into a gas.

Vapour

The gaseous phase of a substance that is typically a solid or liquid at normal room temperature.

Volatile Liquid

A liquid substance that readily vaporises or evaporates at room temperature, such as petrol.

Condensation

The physical change of state where a gas or vapour cools down and turns into a liquid.

Sublimation

The phase transition in which a solid changes directly into a gas without passing through an intermediate liquid state.

Chemical Change

A process in which atoms rearrange to break or form new bonds, resulting in one or more new substances with distinct properties.

Precipitate

Solid particles formed in a liquid solution during a chemical reaction.

Reactants

The initial starting substances present before a chemical reaction takes place.

Products

The final new substances produced as a result of a chemical reaction.

Combustion

A chemical reaction in which a substance reacts rapidly with oxygen, releasing heat and light energy; commonly known as burning.

Chemical Equation

A shorthand expression using symbols and formulas to represent a chemical reaction, displaying reactants on the left and products on the right.

Collision Theory

A theory stating that chemical reactions occur when reactant particles physically collide with one another with sufficient energy.

Concentration

The number of particles of a substance present within a specific volume.

Catalyst

A substance that speeds up the rate of a chemical reaction without being consumed or permanently altered in the reaction.

Enzyme

A specialized biological catalyst that speeds up chemical processes within living organisms.

Corrosion

A chemical reaction between a substance, typically a metal, and its surrounding environment that causes the material to degrade.

Rusting

The specific chemical corrosion of iron or steel upon reacting with oxygen and moisture to form reddish-brown iron oxide.