Unit 2: Matter and Chemical Change Study Guide

Comprehensive vocabulary flashcards covering WHMIS safety symbols, the classification and particle model of matter, atomic structure and history, periodic table trends and families, and chemical compounds.

WHMIS

Workplace Hazardous Materials Information System; a comprehensive system for providing health and safety information on hazardous products used in Canadian workplaces.

Health Hazard (WHMIS)

A hazard symbol indicating a substance that may cause or is suspected of causing serious long-term health effects, such as cancer or birth defects.

Poisonous/Toxic with Immediate Effects (WHMIS)

A hazard symbol (skull and crossbones) indicating substances that can cause death or toxicity with short exposure or small amounts.

Poisonous/Toxic with Other Toxic Effects (WHMIS)

A hazard symbol (exclamation mark) indicating substances that may cause less serious health effects (such as skin or eye irritation, sensitivity, or lung damage) or damage to the ozone layer.

Corrosive (WHMIS)

A hazard symbol indicating materials that cause chemical damage to metals as well as human skin and eyes.

Biohazard (WHMIS)

A hazard symbol for organisms or toxins that can cause diseases in people or animals, such as blood, bacteria, and viruses.

Oxidizing Chemical (WHMIS)

A substance that releases oxygen ($O_2$), which significantly increases the risk and intensity of a fire; identified by a flame over an "O" symbol.

Flammable (WHMIS)

A hazard symbol (flame) representing a fire hazard from materials capable of catching fire easily.

Compressed Gas (WHMIS)

A hazard symbol indicating gases stored under pressure, which can cause a hazardous reaction or explosion if heated or dropped.

Explosive (WHMIS)

A hazard symbol designating substances that pose severe explosion or reactive hazards.

Matter

A physical substance that occupies space and makes up everything in the physical universe.

Pure Substances

Substances that contain only one specific type of particle throughout.

Elements

Pure substances that cannot be broken down into simpler substances by chemical means.

Compounds

Pure substances formed by a chemical bond between two or more different elements in fixed proportions.

Mixtures

Physical combinations of two or more substances that are not chemically bonded together.

Homogeneous Mixture

A mixture containing many particles that are evenly mixed together so the distinct components cannot be distinguished visually.

Heterogeneous Mixture

A mixture where the different types of particles and components can be visibly seen and distinguished.

Particle Model of Matter

A scientific model stating: 1. All matter is made of very small particles too small to be seen with the naked eye; 2. Particles have spaces between them and never touch; 3. Particles attract each other; 4. All particles in a pure substance are identical; 5. As particles gain kinetic energy, they vibrate faster.

Solid

A state of matter characterized by a fixed shape, fixed volume, the least amount of energy, and particles that vibrate in place.

Liquid

A state of matter that takes the shape of its container, has a fixed volume, a medium amount of energy, and particles that exhibit transitional movement (flowing past one another).

Gas

A state of matter with no fixed shape, no fixed volume, the most amount of energy, and particles that vibrate and rotate constantly.

Atomic Number

The number of protons an element contains in its nucleus. In a neutral element, this also equals the total number of electrons.

Atomic Mass

The total number of protons and neutrons in one atom of an element ($\text{Atomic mass} = \#p + \#n$), where each proton and neutron has a mass of approximately $1\,\text{AMU}$.

Atomic Symbol

The one- or two-letter abbreviation used on the periodic table to represent the name of an element (e.g., $O$ for oxygen, $Au$ for gold).

Ion

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

Cation

A positively charged ion formed by the loss of one or more electrons, resulting in more protons than electrons (e.g., $Au^{3+}$ is named Gold ion).

Anion

A negatively charged ion formed by the gain of one or more electrons, resulting in more electrons than protons; named using the element's first syllable followed by the suffix "-ide" (e.g., nitrogen forms nitride).

Isotopes

Atoms of the same chemical element that contain the same number of protons but different numbers of neutrons (e.g., carbon-$12$ with $6$ neutrons vs. carbon-$13$ with $7$ neutrons).

Antoine Lavoisier

An 18th-century French chemist known as the "father of modern science" who conducted careful experiments, assisted in developing the metric system, defined elements as pure substances, and defined the Law of Conservation of Mass.

John Dalton

An 1800s scientist who formulated the first modern particle theory: all matter is made of indivisible atoms, atoms of the same element are identical in mass and size, and compounds form when elements link in definite proportions.

Dmitri Mendeleev

A Russian chemist who in the 1860s created the first periodic table ordered by atomic mass, discovered periodic repeating properties, and accurately predicted the existence and properties of undiscovered elements.

Billiard Ball Model

An early atomic model proposed by John Dalton in 1800 that depicted atoms as solid, uniform spheres of varying sizes.

Plum Pudding Model

An atomic model proposed by J.J. Thomson in 1904 following his discovery of the electron, depicting negative electrons ($e^-$) embedded within a generally positive spherical atom.

Planetary Model

An atomic model proposed by Ernest Rutherford in 1911 showing that the atom is mostly empty space with a dense, positively charged nucleus in the center containing protons and neutrons, orbited by electrons.

Bohr Model

An atomic model introduced in 1913 hypothesizing that electrons travel in circular paths around the nucleus called fixed shells, orbitals, or energy levels.

Valence Electrons

The electrons located in the outermost occupied shell or energy level of an atom.

Metals

Elements that are good conductors of heat and electricity, malleable, ductile, shiny, and solid at room temperature (with the exception of liquid mercury, $Hg$).

Metalloids

Elements with intermediate properties between metals and non-metals; they act as semiconductors of heat and electricity, are solids at room temperature, are not malleable or durable, and can appear shiny or dull.

Non-metals

Elements that do not conduct heat or electricity, are brittle, dull, not durable, and exist as solids, liquids, or gases at room temperature.

Periods

The horizontal rows on the periodic table that indicate the number of occupied electron shells or energy levels.

Groups / Families

The vertical columns on the periodic table of elements sharing similar chemical properties and having the same number of valence electrons.

Alkali Metals

Group 1 elements (excluding hydrogen) with 1 valence electron; they are the most reactive metals, highly reactive in water, have a single unpaired electron, and readily form $1+$ ions.

Alkaline Earth Metals

Group 2 metallic elements that have 2 valence electrons; reactive metals that lose both valence electrons to achieve stability by forming $2+$ ions or compounds.

Halogens

Group 17 non-metallic elements with 7 valence electrons; the most reactive non-metals, possessing one unpaired electron and readily gaining an electron to form $1-$ ions.

Noble Gases

Group 18 elements that are chemically stable, non-reactive gases with complete outer electron shells containing 8 valence electrons and no unpaired electrons.

Law of Definite Composition

A fundamental chemical principle stating that compounds are pure substances containing two or more elements combined in definite, fixed proportions.

Coefficient

The regular-sized number positioned in front of a chemical formula indicating the total quantity of molecules or formula units present (e.g., the "$2$" in $2H_2O$ indicates two water molecules).

Subscript

The small number written directly following an element's atomic symbol indicating the number of atoms of that element present in one molecule (e.g., the "$2$" in $H_2O$ indicates two hydrogen atoms).

Molecular Compounds

Compounds formed by two or more non-metallic atoms sharing available valence electrons through covalent bonds; typically possess low melting and boiling points and are poor electrical conductors.

Ionic Compounds

Compounds formed between a metal (cation) and a non-metal (anion) through the transfer of electrons, characterized by high melting and boiling points, formation of crystal lattices, and good electrical conductivity when dissolved in water.

Crystal Lattice

The repeating three-dimensional geometric framework formed by the mutual electrostatic attraction between alternating positive cations and negative anions in an ionic solid.

Diatomic Molecules

Molecules naturally consisting of two identical atoms bonded together; specifically $H_2$, $N_2$, $O_2$, $F_2$, $Cl_2$, $Br_2$, and $I_2$.