Atomic Theory and Ions

Vocabulary and key concepts from the lecture notes regarding the definition of ions, John Dalton's atomic theory of 1808, and modern modifications concerning subatomic particles and nuclear fission.

Ions

Any atom or a group of atoms which possess an electric charge.

Cations

The positively charged ions, including examples such as $K^{+}$, $Na^{+}$, $Ca^{2+}$, $Fe^{2+}$, and $NH_4^{+}$.

Anions

The negatively charged ions, including examples such as $OH^{-}$, $Cl^{-}$, $NO_3^{-}$, and $SO_4^{2-}$.

Ion Formation

The process where ions are produced when atoms lose or gain electrons, for example: $Na - e \rightarrow Na^{+}$ or $Cl + e \rightarrow Cl^{-}$.

Atomic theory

The scientific idea that elements are made up of atoms.

John Dalton

A scientist from England who, in $1808$, proposed a famous theory defining atoms and their behavior.

Atoms (Dalton's definition)

Small indivisible particles that make up all elements.

Dalton's First Postulate

States that all elements are made up of small indivisible particles called atoms.

Dalton's Second Postulate

States that atoms cannot be created or destroyed.

Compound Formation (Dalton)

Atoms of different elements can combine in simple whole numbers ratios to form compounds.

Chemical Changes (Dalton)

Changes that result from the combination or the separation of atoms.

Subatomic Particles

The three components identified following Rutherford's discovery that show atoms are not indivisible: protons, neutrons, and electrons.

Nuclear Fission

A process that destroys atoms by breaking nuclei into smaller units, such as a nucleus of $uranium-235$ absorbing a neutron and breaking into fragments.