The Particulate Nature of Matter and Atomic Models

This set of flashcards covers vocabulary and key figures related to the particulate nature of matter, historical atomic theories, and the classification of substances and mixtures.

Macroscopic scale

The larger scale that allows us to visualise objects with the unaided eye.

Microscopic scale

The scale usually too small to be seen with the unaided eye, often requiring models for study.

Structure

One of the two main concepts in the DP chemistry course, concerned with the arrangement of particles in a substance and how this affects physical and chemical properties.

Reactivity

One of the two main concepts in the DP chemistry course, concerned with how and why substances interact with each other.

Atomos

A term coined by Democritus in $400\,BCE$ meaning indestructible, used to describe the point at which matter could no longer be cut.

John Dalton

The British chemist who in $1803$ developed atomic theory, proposing that each element consisted of identical atoms that bond to form compounds.

J. J. Thomson

The British physicist who discovered the electron in $1897$ and proposed the plum pudding model of the atom.

Plum pudding model

An atomic model proposed by J. J. Thomson in which electrons were embedded in a sphere of positive charge.

Hantaro Nagaoka

A Japanese physicist who in $1904$ proposed an atomic model with a positively charged centre surrounded by orbiting electrons, similar to Saturn and its rings.

Ernest Rutherford

The New Zealand physicist who in $1909$ demonstrated that the atom is largely empty space.

Niels Bohr

The Danish physicist who in $1914$ proposed that electrons exist in fixed energy levels and transition between them by absorbing or emitting exact amounts of energy.

Pure substances

Substances like elements and compounds that are made up of one type of substance and have a fixed composition.

Mixtures

Matter composed of two or more pure substances in no fixed ratio that are not chemically bonded and can be separated by physical methods.

Elements

The simplest forms of matter that consist of only one type of atom and cannot be broken down chemically into simpler substances.

Diatomic elements

Elements formed by two atoms of the same element bonded together, such as $H_2$, $N_2$, $O_2$, $F_2$, $Cl_2$, $Br_2$, and $I_2$.

Polyatomic elements

Elements formed by more than two atoms of the same element bonded together, such as phosphorus ($P_4$) and sulfur ($S_8$).

Allotropes

Different forms of an element in the same physical state, such as the different forms of carbon.

Compounds

Pure substances composed of two or more different elements chemically combined in fixed ratios.

Heterogeneous mixture

A mixture with a non-uniform composition and visible phases or boundaries, such as oil and water or iron filings and sulfur.

Homogeneous mixture

A mixture with a uniform composition where the components are equally distributed and in the same state, showing no visible phases.

Solute

The substance that is dissolved in a solvent to form a solution, such as salt in water.

Solvent

The substance that dissolves the solute, such as water in a salt water solution.

Solvation

The process where the solvent particles surround and interact with the particles of the solute.