Modern Atomic Theory

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Quantum Mechanical Model Noun

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[kwon-tuhm muh-kan-i-kuhl mod-l]

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Quantum Mechanical Model

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A modern atomic model describing electron behavior with quantized energies but without defining an exact path around the nucleus.

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Example: This model shows a dense nucleus of protons and neutrons, with electrons existing in a 'cloud' of probable locations rather than fixed circular paths.

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Schrödinger Equation Noun

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[shroh-ding-er ih-kwey-zhuhn]

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Schrödinger Equation

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A mathematical equation describing an electron's behavior in an atom, whose solutions form the basis of the quantum mechanical model.

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Example: This image shows the Schrödinger equation, a core formula in modern atomic theory that helps predict the energy and behavior of electrons in an atom.

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Atomic Orbital Noun

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

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Atomic Orbital

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

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Example: This image shows two types of atomic orbitals: the spherical s-orbital and the dumbbell-shaped p-orbital, representing regions where an electron is likely found.

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Electron Cloud Model Noun

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[ih-lek-tron kloud mod-l]

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Electron Cloud Model

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

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Example: This diagram shows a central nucleus surrounded by a blurry 'cloud,' which represents the probable region where electrons exist, not fixed orbits.

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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 version of the quantum mechanical model that describes the main electron energy levels as distinct shells.

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Example: This diagram shows the shell model for a Sodium atom, with a central nucleus and electrons organized into distinct energy shells (2, 8, 1).

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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 levels within an atom, also known as shells, designated by the principal quantum number 'n'.

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Example: This diagram shows electrons orbiting the nucleus in distinct paths called electron shells, which represent different principal energy levels.

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Subshell Noun

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[suhb-shel]

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Subshell

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A subdivision of a principal energy level, also known as a sublevel, denoted by the letters s, p, d, and f.

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Example: This image shows the different shapes of regions where electrons are found, which are grouped into subshells labeled s, p, and d.

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s orbital Noun

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[es or-bi-tl]

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s orbital

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A spherically shaped atomic orbital that can hold up to two electrons and exists in every principal energy shell.

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Example: This diagram shows that an s-orbital has a simple spherical shape, centered on the atom's nucleus, which is represented by the intersection of the x, y, and z axes.

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p orbital Noun

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[pee or-bi-tl]

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p orbital

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A dumbbell-shaped atomic orbital, with three p orbitals existing in each principal energy shell from n=2 onwards.

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

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d orbital Noun

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[dee or-bi-tl]

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d orbital

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A type of atomic orbital, often with a cloverleaf shape, with five d orbitals existing from principal shell n=3 onwards.

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