Modern Atomic Theory

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Quantum Mechanical Model Noun

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[kwan-tuhm me-kan-i-kuhl mod-l]

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Quantum Mechanical Model

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The modern description of electrons in atoms, derived from the Schrödinger equation, which describes the probable locations of electrons.

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Example: This model shows electrons in a 'cloud' of probable locations around the nucleus, not in fixed orbits, which is the main idea of the quantum mechanical model.

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Atomic Orbital Noun

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[uh-tom-ik or-bi-tuhl]

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Atomic Orbital

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A three-dimensional region of space around an atom's nucleus where there is a high probability of finding an electron.

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Example: This image shows that some atomic orbitals have specific 3D shapes, like the dumbbell shape of these p-orbitals oriented along x, y, and z axes.

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Electron Cloud Model Noun

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[ih-lek-tron klowd mod-l]

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Electron Cloud Model

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A visual representation of an atom where the probable locations of electrons are shown as a fuzzy, cloud-like region.

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Example: This diagram shows the electron cloud model, where an electron exists in a 'cloud' of probable locations around the central proton, not a fixed orbit.

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Shell Model Noun

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[shel mod-l]

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Shell Model

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A simplified model of the atom that describes the main electron energy levels as distinct shells at different distances from the nucleus.

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Example: This diagram shows the shell model of an atom, where electrons orbit a central nucleus in distinct paths called electron shells.

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Principal Energy Level Noun

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[prin-suh-puhl en-er-jee lev-uhl]

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Principal Energy Level

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The main energy level of an electron within an atom, also called a shell, denoted by the integer 'n'.

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Example: This diagram shows electrons (blue dots) in specific circular paths around a nucleus. Each path, or shell, represents a different principal energy level.

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Subshell Noun

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[sub-shel]

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Subshell

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A subdivision of a principal energy level, consisting of one or more orbitals and designated by the letters s, p, d, and f.

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Example: This diagram shows that a large electron shell is made of smaller groups called subshells, which are paths where electrons are found.

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s orbital Noun

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[es or-bi-tuhl]

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s orbital

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A type of atomic orbital that has a spherical shape, with one s orbital present in every principal energy level.

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Example: This image shows an s-orbital, the simplest type of electron orbital, which has a spherical shape centered around the atom's nucleus.

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p orbital Noun

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[pee or-bi-tuhl]

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p orbital

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A type of atomic orbital that has a dumbbell shape, with three p orbitals present in each shell from n=2 onwards.

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Example: This image shows a p-orbital, which is a dumbbell-shaped region around an atom's nucleus where an electron is likely to be found.

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d orbital Noun

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[dee or-bi-tuhl]

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d orbital

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A type of atomic orbital, most of which have a cloverleaf shape, with five d orbitals comprising the d subshell.

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Example: This image shows the five different shapes and orientations of d-orbitals, which are regions in an atom where electrons are likely to be found.

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f orbital Noun

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[ef or-bi-tuhl]

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f orbital

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A type of atomic orbital with a complex, multi-lobed shape, with seven f orbitals comprising the f subshell.

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Example: This image shows a 3D model of an f orbital, one of the complex shapes that describe where an electron is likely to be found in an atom.