Modern Atomic Theory Test

Excited State

An atom is in an excited state when it possesses more energy than in its ground state.

Ground State

An atom is in its ground state when it is in its lowest possible energy state.

Photon

A discrete quantity of electromagnetic radiation. (a packet of energy)

Orbital

A region in space where there is a 90% probability of finding an electron.

s subshell capacity

A particular s-subshell can hold a maximum of 2 electrons.

p subshell capacity

A p subshell consists of three orbitals and can hold a maximum of 6 electrons.

p orbital capacity

A specific p orbital can hold a maximum of 2 electrons of opposite spin.

Valence Electrons

The electrons in the outermost shell of an atom.

Core Electrons

Electrons in principal energy levels closer to the nucleus than the outermost shell.

Periodic Table Arrangement

The periodic table is arranged based on the electronic structure of the atoms.

Electron Configuration of Na

1s² 2s² 2p⁶ 3s¹.

Electron Configuration of N

1s² 2s² 2p³.

Electron Configuration of Be

1s² 2s².

Electron Configuration of Sr

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² or [Kr] 5s².

Ionization Energy

The energy required to remove an electron from an atom.

Atomic Radius

The distance from the center of the nucleus to the outer edge of the valence electrons.

Ionization Energy Trend in Groups

Ionization energies decrease from top to bottom in a vertical group.

Atomic Size Trend in Groups

Atomic radius increases from top to bottom in a vertical group.

Ionization Energy Trend in Periods

Atomic sizes decrease across a horizontal row of the periodic table.

Atom's return to ground state

An excited atom returns to its ground state by emitting excess energy as electromagnetic radiation.

Photon Energy and Wavelength Relation

Longer wavelength photons carry less energy than shorter wavelength photons.

Wave Mechanical Orbitals vs. Bohr’s Orbits

Wave-mechanical orbitals predict probabilities of finding electrons rather than specific paths.

Unpaired Electrons in p Orbitals

Unpaired electrons are placed in separate p orbitals to minimize interelectronic repulsion.

Electrons in Principal Energy Levels

The first principal level can hold 2 electrons; the second can hold a maximum of 8 electrons.

Valence Electrons Importance

Valence electrons affect an atom's chemical properties and are related to the atom's position on the periodic table.

Excited States Emission of Radiation

Excited atoms emit only discrete photons of characteristic wavelength and energy.

Trend Explanation for Atomic Radius

Atomic radius decreases across periods due to increased nuclear charge, while it increases down groups due to additional energy levels.

Shorthand Electron Configuration

Core electrons are represented by the closest noble gas, conveying only the valence electrons and their orbitals.

Energy Level, Sublevel, and Orbital Definition

Energy levels are discrete states, sublevels are divisions within energy levels, and orbitals are probable locations of electrons.