States of Matter, Atomic Structure, and the Periodic Table

Vocabulary practice flashcards covering states of matter, atomic history, sub-atomic particles, atomic structure, and the periodic table based on chemistry lecture notes.

Kinetic theory of matter

A theory based on the fact that all matter is made up of tiny particles, describing particle movement and the average distance between particles in solids, liquids, and gases.

Solid

A state of matter with a fixed shape and volume that cannot be compressed, where particles touch their nearest neighbours in a fixed arrangement and vibrate constantly.

Liquid

A state of matter with a fixed volume that can flow and change shape, where particles are very close together but move past each other in a constantly changing, random arrangement.

Gas

A state of matter with no fixed shape or volume that can be compressed easily, where particles have lots of space between them and move at high speeds in random directions.

Sublimation

The change of state that occurs when a solid is heated and changes directly to a gas without melting or passing through the liquid phase.

Heating curve of a solid

A plot of temperature against time showing that when a solid is heated to its melting point, its temperature remains constant until all the solid has melted, as energy is absorbed to break forces between particles.

John Dalton's atomic theory

An early 1800s theory proposing that all substances are made up of indivisible, tiny hard sphere atoms, where each chemical element has its own atoms differing in mass.

Electron

A tiny, negatively charged sub-atomic particle discovered by J. J. Thomson, having a relative charge of $-1$ and a mass about $2000$ times smaller than the lightest atom.

Plum pudding model

An atomic model proposed by J. J. Thomson where tiny, negatively charged electrons are embedded inside a cloud of positive charge.

Alpha particle scattering experiment

An experiment where Ernest Rutherford's students fired dense, positively charged alpha particles at thin gold foil, demonstrating that the positive charge of an atom is concentrated in a tiny central nucleus.

Bohr model of the atom

An atomic model revised by Niels Bohr in $1914$, proposing that electrons orbit the nucleus at set distances in fixed energy levels or shells.

Neutron

An uncharged sub-atomic particle located in the nucleus with the same mass as a proton, discovered by James Chadwick in $1932$.

Element

A substance made up of only one type of atom, with about $100$ total elements existing (and $92$ occurring naturally on Earth).

Compound

A substance made up of different types of atoms tightly joined together by chemical bonds.

Metalloid

An element located next to the dividing staircase line on the periodic table that exhibits both metallic and non-metallic characteristics, such as silicon ($\text{Si}$) and germanium ($\text{Ge}$).

Molecule

A grouping of two or more atoms held together by chemical bonds, such as a water molecule.

Proton

A positively charged sub-atomic particle located inside the nucleus of an atom, with a relative charge of $+1$.

Atomic number

The number of protons in the nucleus of an atom, which determines its position on the periodic table and identity as an element.

Mass number

The total number of protons plus neutrons in the nucleus of an atom.

Carbon atom structure

An atom of carbon consists of $6$ protons and $6$ neutrons in its central nucleus, surrounded by $6$ orbiting electrons.

Dmitri Mendeleev's periodic table

A table published in $1869$ arranging elements by atomic mass and leaving gaps for undiscovered elements to maintain groups of elements with similar properties.

Group (periodic table)

A vertical column in the periodic table containing elements with similar chemical properties because their atoms have the same number of electrons in their outermost shell.

Period (periodic table)

A horizontal row of elements in the periodic table.

Noble gases

Group $0$ non-metal monatomic gases that are unreactive due to having very stable electronic structures with $8$ electrons in their outermost shell (or $2$ for helium).

Modern periodic table

The layout arranging chemical elements in order of increasing atomic (proton) number so that elements line up in vertical groups with similar outer-shell electron structures.