Unit 2 Chemistry Review: Atomic Structure and Periodic Trends

Comprehensive vocabulary flashcards covering atomic structure models, subatomic particles, isotope notation, electron configuration rules, and periodic trends based on the Unit 2 Review Packet.

Dalton's Atomic Model

The solid sphere model proposing that atoms are indivisible and indestructible spheres.

Plum Pudding Model

J.J. Thomson's atomic model depicting a positively charged sphere with negatively charged electrons floating around inside.

Rutherford's Atomic Model

The nuclear model developed after the gold foil experiment, which discovered that an atom contains a central nucleus.

Bohr Model

An atomic model demonstrating that electrons travel around the nucleus in fixed orbits.

Wave Model (Schrodinger)

The quantum mechanical model created by Erwin Schrödinger, recognized as the most accurate atomic model today.

Dmitri Mendeleev

An early chemist who created the periodic table and intentionally left blank spaces for undiscovered elements he knew existed.

Allotrope

Different structural forms of the same chemical element in the same physical state, such as diatomic oxygen ($O_2$) and ozone ($O_3$).

Atomic Number

The number of protons in an atom, represented by $Z$, which determines the identity of an element.

Mass Number

The total number of protons and neutrons in the nucleus of an atom, designated by the symbol $A$.

Proton

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

Neutron

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

Electron

A negatively charged subatomic particle found in the electron cloud surrounding the nucleus.

Isotope

Atoms of the same element containing the same number of protons but a different number of neutrons, resulting in different masses.

Aufbau Principle

The rule stating that electrons must occupy the lowest energy subshells first before filling higher energy levels.

Hund's Rule

The rule stating that electrons (represented by upward arrows) must occupy empty degenerate orbitals singly before pairing up with opposite-spin electrons (downward arrows).

Pauli Exclusion Principle

The principle stating that an orbital can hold a maximum of two electrons, and those two electrons must have opposite spins.

Groups (Periodic Table)

The vertical columns on the periodic table whose elements share the same number of valence electrons and exhibit similar chemical properties.

Periods (Periodic Table)

The horizontal rows of elements on the periodic table.

Alkali Metals

The family of chemical elements comprising Group 1 of the periodic table.

Alkaline Earth Metals

The family of chemical elements comprising Group 2 of the periodic table.

Transition Metals

The metallic elements located in Groups 3 through 12 of the periodic table.

Halogens

The reactive nonmetal elements located in Group 17 of the periodic table.

Noble Gases

The inert nonmetal elements located in Group 18 of the periodic table.

Periodic Table Staircase Line

The zigzag line running down the right side of the periodic table; metalloids sit along the line, metals lie to the left, and nonmetals lie to the right.

Atomic Radius (Periodic Trend)

A periodic trend that increases down a group (from smaller to bigger) and decreases across a period from left to right (from bigger to smaller).

Electronegativity (Periodic Trend)

A periodic trend that decreases down a group (from bigger to smaller) and increases across a period from left to right (from smaller to bigger).

Ionization Energy (Periodic Trend)

A periodic trend that decreases down a group (from bigger to smaller) and increases across a period from left to right (from smaller to bigger).

Fluorine (Electronegativity)

The chemical element with the highest electronegativity value because its valence electrons are closest to the nucleus, exerting the strongest pull on shared electrons.

Francium (Electronegativity)

The chemical element with the lowest electronegativity value because its outer electrons are farthest from the nucleus on the lower left of the table, making the nuclear pull weakest.