2.05-2.07 Chem

Heisenberg Uncertainty Principle

An electron's position and momentum cannot both be known precisely.

Quantum Mechanical Model

A model describing electrons in probability regions called electron clouds.

Bohr Model Limitation

Cannot accurately predict spectra of multi-electron atoms.

Erwin Schrödinger

Developed equations describing the probability of finding an electron in a certain location.

Louis de Broglie

Proposed that electrons have both wave and particle properties.

Principal Energy Level

The main energy level of an electron represented by n.

Sublevel

A region within a principal energy level designated s, p, d, or f.

Atomic Orbital

A region within a sublevel that can hold up to two electrons.

Electron Spin

A property of electrons represented by up or down arrows.

Pauli Exclusion Principle

No two electrons in the same atom can have identical sets of four quantum numbers.

Maximum Electrons in an Orbital

2 electrons with opposite spins.

Number of Orbitals in s

1 orbital.

Number of Orbitals in p

3 orbitals.

Number of Orbitals in d

5 orbitals.

Number of Orbitals in f

7 orbitals.

Maximum Electrons in s

2 electrons.

Maximum Electrons in p

6 electrons.

Maximum Electrons in d

10 electrons.

Maximum Electrons in f

14 electrons.

Electron Configuration

Shows the probable locations of electrons in an atom.

Aufbau Principle

Electrons fill orbitals in order of increasing energy.

Hund's Rule

Electrons occupy equal-energy orbitals individually before pairing.

Degenerate Orbitals

Orbitals within the same sublevel that have equal energy.

Ground State Electron Configuration

The arrangement of electrons in their lowest available energy orbitals.

Excited State Electron Configuration

An arrangement where electrons occupy higher-energy orbitals than normal.

Valence Energy Level

The highest occupied principal energy level in an atom.

Valence Electrons

Electrons in the highest occupied principal energy level.

Noble Gas Configuration

An abbreviated electron configuration using the preceding noble gas in brackets.

Isoelectronic Species

Atoms or ions of different elements with identical electron configurations.

Oxygen Electron Configuration

1s² 2s² 2p⁴.

Aluminum Electron Configuration

1s² 2s² 2p⁶ 3s² 3p¹.

Carbon Ground State Configuration

1s² 2s² 2p².

Chromium Electron Configuration

[Ar] 4s¹ 3d⁵.

Copper Electron Configuration

[Ar] 4s¹ 3d¹⁰.

Orbital Notation

Uses boxes or lines for orbitals and arrows for electrons and their spins.

Periodic Table Group

A vertical column of elements with similar properties.

Periodic Table Period

A horizontal row of elements with the same valence energy level.

Representative Elements

Main-group elements with predictable valence electron patterns.

Metals

Shiny, malleable, ductile, and good conductors of heat and electricity.

Nonmetals

Generally poor conductors that are not malleable or ductile.

Metalloids

Elements with properties of both metals and nonmetals.

Malleable

Able to be hammered or shaped into sheets.

Ductile

Able to be drawn into wires.

Lustrous

Having a shiny appearance.

Alkali Metals

Group 1 metals with 1 valence electron and a typical +1 charge.

Alkaline Earth Metals

Group 2 metals with 2 valence electrons and a typical +2 charge.

Transition Metals

Groups 3–12 metals that can have variable positive charges.

Halogens

Group 17 elements with 7 valence electrons and a typical -1 charge.

Noble Gases

Group 18 elements that are generally chemically unreactive.

Lanthanides and Actinides

The two series of f-block elements.

Most Reactive Metals

Alkali metals in Group 1.

Most Reactive Nonmetals

Halogens in Group 17.

Group 1 Charge

+1.

Group 2 Charge

+2.

Group 16 Charge

-2.

Group 17 Charge

-1.

Group 18 Charge

0.

Noble Gas Valence Electrons

8 except helium which has 2.

Diatomic Elements

H₂, N₂, O₂, F₂, Cl₂, Br₂, and I₂.

Dmitri Mendeleev

Organized elements by atomic mass and properties and predicted undiscovered elements.

Henry Moseley

Established atomic number as the basis for organizing the modern periodic table.

Johann Döbereiner

Proposed the law of triads in 1829.

John Newlands

Proposed the law of octaves in 1864.

Law of Triads

Groups of three similar elements with the middle atomic mass approximately averaging the other two.

Law of Octaves

An early pattern suggesting similar elemental properties repeat every eighth element.

Mendeleev's Periodic Law

Element properties are periodic functions of their atomic masses.

Modern Periodic Law

Element properties are periodic functions of their atomic numbers.

Mendeleev's Predicted Elements

Gallium, germanium, and scandium.