2 Chemistry: 2.1 The Composition of Matter

Vocabulary flashcards covering key terms related to matter, mixtures, separation methods, and atomic structure from the section 2.1.

matter

Anything that has mass and occupies space; chemists study its structure, transformations, and the energy involved in those transformations.

atom

The basic unit of matter that combines with other atoms to form molecules; the building block of elements.

mixtures

A physical blend of two or more substances in varying proportions; components are not chemically bonded.

Pure substances

Matter with a definite, uniform composition; can be elements or compounds.

Heterogeneous mixture

A mixture with distinct phases that can be visually distinguished.

Homogeneous mixture

A mixture with uniform composition in a single phase.

Immiscible liquids

Two liquids that do not mix to form a single phase (e.g., water and oil) and separate into distinct layers.

Saltwater

A homogeneous solution in which salt is dissolved in water.

Physical separation methods

Techniques to separate mixture components based on physical properties without chemical changes.

Chemical separation methods

Techniques to separate components through chemical changes, often forming new substances.

Evaporation

A physical separation method where a solvent is evaporated to leave dissolved solids behind.

NaCl (sodium chloride)

Sodium chloride; an ionic compound formed from Na+ and Cl- ions.

Sodium cation (Na+)

Positively charged ion derived from sodium.

Chloride anion (Cl-)

Negatively charged ion formed from chlorine.

Nucleus

Center of the atom containing protons and neutrons; houses most of the atom’s mass.

Protons

Positively charged subatomic particles in the nucleus; +1 charge; 1.6×10^-19C, mass ~1.67×10^-27 kg.

Neutrons

Electrically neutral subatomic particles in the nucleus; mass similar to protons.

Electrons

Negatively charged subatomic particles that orbit the nucleus; -1 charge; mass ~9.11×10^-31 kg.

Rutherford model

First atomic model (1911) proposing a nucleus with protons and neutrons, with electrons orbiting around it.

Nucleons

Protons and neutrons; the particles that form the atomic nucleus.