Chapter 2: Components of Matter

Vocabulary practice flashcards covering fundamental definitions, subatomic particles, physical separation techniques, chemical laws, atomic structure, isotopes, and bonding types from Chapter 2.

Chemistry

The study of matter, its structure, properties, and the processes it undergoes.

Matter

Anything that has mass and occupies space, coming from the Latin word materia, meaning material.

Pure Substance

A sample of matter which cannot be separated or divided into simpler components by physical means, exhibiting a uniform or invariable composition from one sample to the next.

Element

The simplest type of substance with unique physical and chemical properties, consisting of only one type of atom, which cannot be broken down into any simpler substances by physical or chemical means.

Compound

A substance composed of two or more elements that are joined together in fixed, definite proportions; it can be broken down into simpler substances by chemical means, but not by physical means.

Molecule

A structure that consists of two or more atoms that are chemically bound together and thus behaves as an independent unit.

Mixture

Matter composed of two or more components such that they can have variable composition from one sample to the next.

Homogeneous Mixture

A mixture characterized by having a composition which is the same or uniform throughout a given sample.

Heterogeneous Mixture

A mixture that is not uniform throughout a given sample, varying in its composition when comparing one region of the sample to the next.

Filtration

A separation technique that separates components of a mixture based upon differences in particle size, usually involving separating a precipitate from solution.

Crystallization

A separation technique based upon differences in solubility of the components in a mixture.

Distillation

A separation technique based upon differences in volatility, which is the tendency of a substance to become a gas.

Chromatography

A separation technique based upon differences in solubility in a solvent versus a stationary phase.

Law of Mass Conservation

States that the total mass of substances involved in a chemical reaction does not change, and thus matter is not created nor destroyed during the reaction.

Law of Definite Composition

States that all samples of a particular compound are composed of the same elements with the same proportions of those elements by mass, no matter what their source or how they were prepared.

Law of Multiple Proportions

States that if two elements react to form two different compounds, then the two masses of element 2 that combine with a fixed mass of element 1 in each of the two compounds can be expressed as a ratio of small whole numbers.

Radioactivity

The phenomenon exhibited by certain elements wherein radiation (such as alpha particles, beta particles, or gamma rays) is emitted due to changes in the atomic nucleus.

Cathode Rays

Streams of low-mass, negatively charged particles (electrons) that travel from the cathode to the anode in a cathode ray tube.

Plum Pudding Model

An atomic model proposed by J. J. Thomson where negatively charged electrons are distributed throughout a sphere of positive charge.

Nucleus

A dense collection of subatomic particles (protons and neutrons) at the center of an atom that constitutes essentially the entire mass of the atom.

Proton

A positively charged subatomic particle residing in the nucleus of an atom, having a relative charge of $+1$, a mass of $1.00727\,\text{amu}$, or $1.67262 \times 10^{-24}\,\text{g}$.

Neutron

A subatomic particle of neutral charge residing in the nucleus of an atom, having a relative charge of $0$, a mass of $1.00866\,\text{amu}$, or $1.67493 \times 10^{-24}\,\text{g}$.

Electron

A low-mass, negatively charged subatomic particle residing in orbitals around the atomic nucleus, having a relative charge of $-1$, a mass of $0.00055\,\text{amu}$, or $0.00091 \times 10^{-24}\,\text{g}$.

Atomic Mass Unit (amu)

A unit of mass defined as being $\frac{1}{12}$ the mass of a carbon-12 atom.

Mass Number

The total number of protons and neutrons associated with a given atom of an element, defined as $\text{Mass Number} = \text{number of protons} + \text{number of neutrons}$.

Isotopes

Atoms that have the same atomic number (number of protons) but different mass numbers due to having different numbers of neutrons.

Isotope Abundance

The fraction or percentage of naturally occurring atoms of an element that consist of a given isotope.

Periodic Law

States that if the chemical elements are arranged in order of increasing relative mass, their chemical and physical properties recur at various intervals in a cyclical or periodic manner.

Ion

An atom or group of atoms that has acquired an electrical charge imbalance by gaining or losing one or more electrons.

Anion

A negatively charged ion formed when an atom or group of atoms gains electrons.

Cation

A positively charged ion formed when an atom or group of atoms loses electrons.

Ionic Bond

A chemical bond formed when electrons are transferred from one element to another, typically formed between a metal and a nonmetal.

Covalent Bond

A chemical bond formed when elements share electrons, typically formed between two nonmetals.

Polyatomic Ion

An ion composed of two or more atoms covalently bonded together that possesses an overall electrical charge.

Hydrate

An ionic compound that contains a specific number of water molecules bound within each formula unit.

Binary Acid

An acid solution formed when certain covalent, gaseous compounds dissolve in water and ionize to produce $\text{H}^+(aq)$ cations.

Oxoacid

An acid compound containing hydrogen bound to an oxoanion.