Chemistry: Atomic Theory, Periodic Table, Matter, and Ion Formation

Vocabulary flashcards reviewing core chemistry concepts from the provided lecture series, including atomic theory, classification of matter, atomic structure, the periodic table, and ion formation.

Element

A pure substance that cannot be broken down into simpler substances by chemical means. Examples include gold, sulfur, and carbon.

Atom

The smallest part of an element that retains all the properties of that element, forming the basic building block of all matter.

Billiard Ball Model

The atomic model proposed by John Dalton in 1808, which described atoms as small solid spheres that varied in size, mass, and colour depending on their properties.

Plum Pudding Model

The atomic model proposed by J.J. Thomson in 1897, depicting the atom as consisting mostly of a positively charged sphere with negative charges embedded within it.

Gold Foil Experiment

An experiment conducted by Ernest Rutherford in 1911 in which alpha particles were shot at gold foil, demonstrating that the atom is mostly empty space with a tiny, positively charged nucleus.

Solar System Model

The atomic model proposed by Niels Bohr in 1913, proposing that protons are located in the nucleus and electrons move around the nucleus in definite energy levels or orbits.

Electron Cloud Model

The atomic model proposed by Louis de Broglie and Erwin Schrödinger in 1930, asserting that electrons form a cloud around the nucleus where their exact locations are not precisely defined.

Atomic Number

The number of protons in the nucleus of an atom, which specifies the element; in a neutral atom, it also equals the number of electrons.

Atomic Mass

The average mass of an element's naturally occurring isotopes, as displayed on the periodic table.

Mass Number

The total number of protons and neutrons in the nucleus of an atom, calculated as $\text{Mass Number} = \text{Number of Neutrons} + \text{Number of Protons}$.

Period (Periodic Table)

A horizontal row on the periodic table, numbered by atomic number, where the period number indicates the number of occupied energy levels in an atom.

Group (Periodic Table)

A vertical column on the periodic table containing elements with similar physical and chemical properties; the group number indicates the number of valence electrons.

Metal

A class of elements comprising most of the periodic table that are typically silvery or grey, shiny, malleable, ductile, good conductors of heat and electricity, and solid at room temperature (except Mercury).

Non-Metal

A class containing $17$ elements located on the right side of the periodic table that vary in colour, state at room temperature, and reactivity.

Metalloid

An element located between metals and non-metals on the periodic table with intermediate properties, such as conducting electricity poorly.

Alkali Metals

Group $1$ elements on the periodic table (excluding hydrogen) including lithium, sodium, potassium, rubidium, cesium, and francium, which are soft, shiny, silver, and extremely reactive with water.

Alkaline Earth Metals

Group $2$ elements on the periodic table that are reactive metals always found combined with non-metals in nature and serve as important mineral nutrients such as magnesium and calcium.

Transition Metals

Elements in Groups $3$ through $12$ on the periodic table that are harder, less reactive metals commonly used in construction and jewelry.

Halogens

Group $17$ non-metal elements—fluorine, chlorine, bromine, and iodine—that are volatile, diatomic, poisonous, and react readily with alkali metals to form salts.

Noble Gases

Group $18$ elements—helium, neon, argon, krypton, xenon, and radon—that have a full valence shell of electrons, making them extremely unreactive.

Matter

Anything that has mass and occupies space, possessing both physical and chemical properties.

Physical Property

An observable feature of matter, such as colour, density, boiling point, melting point, texture, electrical conductivity, smell, or taste.

Chemical Property

A characteristic describing how a substance reacts with another substance, such as flammability, combustibility, or reaction with water to produce gas.

Physical Change

A change that alters the appearance or state of a substance without altering its chemical composition or producing a new substance, making it reversible.

Chemical Change

A process where a chemical reaction occurs to form one or more new substances, evidenced by bubbles, precipitate formation, colour change, heat or light emission, or odour formation.

Pure Substance

A type of matter consisting of a single kind of substance that always maintains a constant composition and uniform properties, classified as either an element or a compound.

Compound

A pure substance composed of two or more different types of chemically combined atoms that can be broken down into simpler substances by chemical means.

Mixture

A physical combination of two or more pure substances that can be separated and classified as either homogeneous or heterogeneous.

Homogeneous Mixture

Also known as a solution, a mixture in which the solute and solvent are uniformly distributed so that separate components are not visible.

Solute

The component of a solution that is dissolved by the solvent.

Solvent

The component of a solution that does the dissolving.

Heterogeneous Mixture

Also known as a mechanical mixture, a combination in which individual parts remain distinct and visibly separate.

Suspension

A heterogeneous mechanical mixture in which components exist in different states of matter, such as pulp in orange juice or sand in a sandstorm.

Colloid

A heterogeneous mechanical mixture in which finely suspended particles cannot easily be separated from the rest of the mixture, such as milk or whipped cream.

Proton

A positively charged subatomic particle located inside the nucleus of an atom.

Neutron

A neutral subatomic particle with no charge located inside the nucleus of an atom.

Electron

A negatively charged subatomic particle that orbits surrounding the nucleus in specific energy levels.

Bohr Diagram

A visual representation of an atom showing the number of protons and neutrons in the nucleus and electrons occupying discrete energy levels, where the first level holds up to $2$ electrons, the second holds up to $8$, and the third holds up to $8$.

Isotope

Atoms of the same element that have the same number of protons but different numbers of neutrons, resulting in different atomic masses.

Valence Electrons

The electrons occupying the outermost energy level of an atom, which dictate its chemical reactivity and bonding properties.

Octet Rule

The principle stating that atoms gain, lose, or share electrons to achieve a full outer energy level containing $8$ valence electrons, resembling a stable noble gas.

Lewis Dot Diagram

A simplified representation of an atom or ion that displays only its valence electrons as dots surrounding the chemical symbol.

Ionization

The process by which an atom gains or loses electrons to form a charged particle called an ion.

Ion

An atom or group of atoms that has acquired a positive or negative electric charge by losing or gaining one or more electrons.

Cation

A positively charged ion formed when an atom, typically a metal, loses one or more electrons.

Anion

A negatively charged ion formed when an atom, typically a non-metal, gains one or more electrons.

Valence

The tendency of an atom to gain or lose electrons during chemical interactions.