Atomic Structure, Periodic Trends, Chemical Reactions, and Metallic Bonding

Vocabulary flashcards covering atomic structure, historical atomic models, chemical reaction types, balancing methods, periodic trends (ionization energy, atomic radius, electronegativity), the electron gas model, ionic vs. metallic lattices, alloys, and physical properties of metals.

Proton

A subatomic particle located in the nucleus with symbol $p$, a charge of $+1$, and a relative mass of $1.0$.

Electron

A subatomic particle located in the atomic shell with symbol $e$, a charge of $-1$, and a relative mass of $0.0005$.

Neutron

A subatomic particle located in the nucleus with symbol $n$, a charge of $0$, and a relative mass of $1.0$.

Synthesis Reaction

A chemical reaction in which two or more simple substances combine to form a more complex substance ($A + B \rightarrow AB$).

Decomposition Reaction

A chemical reaction in which a compound breaks down into simpler substances ($AB \rightarrow A + B$).

Combustion Reaction

A chemical reaction in which a hydrocarbon ($C_x H_y$) reacts with oxygen ($O_2$) to produce carbon dioxide ($CO_2$), water ($H_2O$), heat, and light.

Activity Series

A ranking of elements used in single replacement reactions to establish that an element cannot replace another element that is more reactive than it.

Atomic Number ($Z$)

The number of protons in an atom, which uniquely determines the identity of the chemical element.

Mass Number ($A$)

The total number of protons and neutrons in the nucleus of an atom ($\text{Neutrons} = A - Z$).

Single-replacement Reaction

A chemical reaction where a more reactive element replaces another element in a compound ($A + BC \rightarrow B + AC$).

Double-replacement Reaction

A chemical reaction in which parts of two ionic compounds are exchanged to form two new compounds.

Law of Conservation of Mass

The principle underpinning chemical reaction balancing, requiring the number of each type of atom to be identical on both sides of a reaction equation.

Ionization

The process by which an atom acquires a positive or negative charge by losing or gaining electrons.

Cation

A positively charged ion formed when an atom loses electrons, resulting in more protons than electrons.

Anion

A negatively charged ion formed when an atom gains electrons, resulting in more electrons than protons.

Dalton's Atomic Model

An early model of the atom that pictured it as indivisible because internal atomic structure was not yet known.

Thomson's Atomic Model

An atomic model that established atoms are divisible by discovering the negative electron and incorporating it into the structure.

Rutherford's Atomic Model

An atomic model based on the gold foil experiment demonstrating that positive charge and most of an atom's mass are concentrated in a tiny nucleus.

Bohr's Shell Model

An atomic model proposing that electrons move in set energy levels (shells) around a nucleus rather than moving at any arbitrary distance.

Electron Shell Capacities (Shells $1$–$7$)

The maximum electron capacities for shells $1$ through $7$ in Bohr's shell model: $2$, $8$, $18$, $32$, $50$, $72$, and $98$ electrons, respectively.

Valence Electrons

The electrons located in an atom's outermost occupied shell.

Lewis Dot Notation Rules

The convention of drawing up to four valence electrons as single dots in the order right-left-top-bottom, doubling them up in the same order if there are more than four, and often combining two paired dots into a line.

Ionization Energy

The energy needed to overcome the electrostatic attraction between a nucleus and an electron to remove an electron from a gaseous atom, leaving behind a positive ion.

Periodic Trend of Ionization Energy

Increases across a period from left to right because the nucleus has more protons attracting electrons more strongly; decreases down a group because outer electrons are farther from the nucleus and shielded by more inner electrons.

Metal Crystal (Microscopic Scale)

A solid packed in an ordered crystal lattice where atomic cores are held together by a sea of delocalised, mobile outer electrons.

Grains (Macroscopic Scale of Metals)

Many tiny crystal regions that combine to form a solid, continuous piece of metal, whose size and orientation determine physical properties.

Isotopes

Atoms of the same element containing the same number of protons but different numbers of neutrons, resulting in different mass numbers.

Atomic Radius

A measure of the size of an atom, which decreases across a period from left to right as added protons pull electrons closer, and increases down a group as additional electron shells place electrons farther from the nucleus.

Electronegativity

A measure of how strongly an atom attracts the shared electrons within a chemical bond.

Periodic Trend of Electronegativity

Increases across a period from left to right because higher nuclear charge attracts bonding electrons more strongly; decreases down a group because bonding electrons are farther from the nucleus and more shielded by inner electrons.

Atomic Cores

Positively charged metal cations formed when metal atoms readily lose valence electrons; they occupy fixed, ordered sites in a regular three-dimensional lattice.

Electron Gas Model

A model of metallic bonding describing a regular lattice of stationary positive atomic cores held together by an uncharged sea of mobile, free valence electrons.

Ionic Lattice

A rigid, uncharged crystal structure composed of alternating cations and anions of different elements held together by electrostatic attraction, with no mobile particles, which breaks under mechanical pressure.

Metal Lattice

A metallic structure composed of positively charged atomic cores of the same element held together by a free electron gas, which deforms without breaking under mechanical pressure.

Alloy

A mixture of a metal with one or more other elements whose added atoms disrupt the regular lattice structure, preventing atom layers from easily sliding past each other and making the material harder and stronger than pure metal.

Mechanical Deformability

The property of metals that allows them to be bent, hammered, or drawn into wires without breaking easily.

Thermal Conductivity of Metals

The ability of a metal to rapidly transfer heat through its structure via mobile electrons.

Electrical Conductivity of Metals

The ability of a metal to conduct electric current through the movement of freely mobile electrons.

Metallic Lustre

The shiny appearance characteristic of metals, caused by mobile surface electrons reflecting incoming light.