Chapter 1: Chemical Foundations - Vocabulary Flashcards

Vocabulary flashcards reviewing fundamental concepts, early history, chemical laws, scientific method, and atomic models from Chapter 1.

Scanning Tunneling Microscope (STM)

A specialized microscope that uses an electron current from a tiny needle to probe the surface of a substance, allowing individual atoms to be visualized.

Macroscopic World

The world of directly observed macroscopic objects and experience, such as cars, tables, rocks, and oceans.

Microscopic World

The realm of atomic and molecular structure that lies beyond direct human sight.

Scientific Method

A process at the center of scientific inquiry that involves making observations, formulating hypotheses, and performing experiments to test those hypotheses.

Qualitative Observation

An observation that describes a property or phenomenon without using numbers or quantitative measurements.

Quantitative Observation

An observation that involves both a numerical value and a unit, also referred to as a measurement.

Hypothesis

A possible explanation for an observation that can be tested by carrying out further experiments.

Theory

A set of tested hypotheses that gives an overall explanation of a natural phenomenon by addressing why nature behaves in a particular way; also called a model.

Natural Law

A concise statement summarizing consistently observed natural behavior that states what happens rather than explaining why it happens.

Law of Conservation of Mass

A fundamental principle stating that mass is neither created nor destroyed in a chemical reaction.

Law of Definite Proportion

A principle stating that a given compound always contains exactly the same proportion of elements by mass.

Law of Multiple Proportions

A principle stating that when two elements form a series of compounds, the ratios of the masses of the second element that combine with $1\,\text{g}$ of the first element can always be reduced to small whole numbers.

Dalton's Atomic Theory

An atomic model established in 1808 stating that elements are composed of atoms, atoms of an element are identical, compounds form from atom combinations, and chemical reactions involve atom reorganization.

Avogadro's Hypothesis

A postulate stating that equal volumes of different gases at the same temperature and pressure contain equal numbers of particles.

Cathode-Ray Tube

A partially evacuated glass tube used by J. J. Thomson to produce a stream of negatively charged particles emanated from a cathode electrode when high voltage is applied.

Electron

A negatively charged subatomic particle with a charge-to-mass ratio of $-1.76 \times 10^8\,\text{C/g}$ and a mass of $9.11 \times 10^{-31}\,\text{kg}$.

Plum Pudding Model

An atomic model postulated by J. J. Thomson that visualizes the atom as a diffuse cloud of positive charge with negative electrons embedded randomly throughout.

Radioactivity

The spontaneous emission of high-energy radiation by certain atomic nuclei, discovered by Henri Becquerel in 1896.

Alpha Particle ($\alpha$ particle)

A radioactive emission consisting of a particle with a $2+$ charge and a mass approximately $7300$ times that of an electron.

Nuclear Atom

Ernest Rutherford's atomic model featuring a dense, central nucleus of positive charge surrounded by electrons moving at a relatively large distance.

Proton

A nuclear particle with a positive charge equal in magnitude to the electron's negative charge ($1+$) and a mass of $1.673 \times 10^{-27}\,\text{kg}$.

Neutron

A nuclear subatomic particle with no electrical charge and a mass of $1.675 \times 10^{-27}\,\text{kg}$, virtually identical to that of a proton.

Isotopes

Atoms of the same element that have identical numbers of protons but different numbers of neutrons, resulting in different mass numbers.

Atomic Number ($Z$)

The number of protons in the nucleus of a given atom, written as a subscript before the chemical symbol.

Mass Number ($A$)

The total number of protons and neutrons in the nucleus of a given atom, written as a superscript before the chemical symbol.

Ion

A net electrically charged species formed when one or more electrons are gained or lost by a neutral atom or group of atoms.

Cation

A positively charged ion produced when a neutral atom loses one or more electrons.

Anion

A negatively charged ion produced when a neutral atom gains one or more electrons.