Atoms, Molecules, and Ions - Early History of Chemistry

These flashcards cover key vocabulary terms and their definitions related to the early history of chemistry, atomic theory, chemical bonds, and the periodic table.

Law of Conservation of Mass

Mass is neither created nor destroyed in a chemical reaction.

Law of Definite Proportion

A given compound always contains exactly the same proportion of elements by mass.

Law of Multiple Proportions

When two elements form a series of compounds, the ratios of the masses of the second element that combine with 1 gram of the first can always be reduced to small whole numbers.

Dalton's Atomic Theory

A theory that states that elements are composed of atoms, compounds are combinations of atoms from different elements, and chemical reactions rearrange atoms.

Isotope

Atoms that have the same atomic number but different mass numbers.

Cation

A positively charged ion that has lost one or more electrons.

Anion

A negatively charged ion that has gained one or more electrons.

Chemical Bond

Forces that hold atoms together in a compound.

Covalent Bond

A bond formed between atoms by sharing electrons.

Ionic Bond

A bond formed due to the attraction between oppositely charged ions.

Empirical Formula

The simplest ratio of elements in a compound.

Molecular Formula

A formula that shows the exact number of atoms of each element in a molecule.

Hydrocarbon

Compounds that consist of only hydrogen and carbon.

Periodic Table

A chart in which elements with similar chemical and physical properties are grouped together.

Hydrate

An ionic compound that contains water molecules as integral components of its crystal.

Acid

A substance that produces hydrogen ions (H+) when dissolved in water.

Radioactivity

The spontaneous emission of radiation by certain unstable atomic nuclei.

X-ray

A type of electromagnetic radiation that can penetrate matter.

Plum Pudding Model

An early model of atomic structure proposed by J.J. Thomson, depicting atoms as a positively charged sphere with electrons embedded in it.

Nucleus

The extremely dense core of an atom, containing protons and neutrons.

Ionization

The process of gaining or losing electrons to form ions.