Lewis Dot Structures

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Valence Shell Noun

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[vay-luhns shel]

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Valence Shell

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The outermost electron shell of an atom which contains the electrons involved in chemical bonding and determines an atom's reactivity.

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Example: This diagram shows an atom's outermost electron shell, the valence shell, and highlights the valence electrons within it that can be gained or lost.

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Valence Electrons Noun

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[vay-luhns ih-lek-trons]

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Valence Electrons

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The electrons located in the outermost shell of an atom that can be transferred or shared with other atoms.

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Example: This Bohr model of a Sodium atom shows its single valence electron, which is the electron located in the outermost shell (energy level).

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Nucleus Noun

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[noo-klee-uhs]

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Nucleus

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The dense, positively charged central region of an atom, composed of protons and neutrons, containing nearly all its mass.

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Example: This diagram shows the nucleus at the center of an atom, containing positively charged protons and neutral neutrons, with electrons orbiting around it.

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Electron Shell Noun

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[ih-lek-tron shel]

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Electron Shell

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A fixed energy level or orbit that electrons occupy as they move around the nucleus of an atom.

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Example: This diagram shows an atom's electrons orbiting the nucleus in specific paths called electron shells, the basis for understanding chemical bonding.

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Atom Noun

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[at-uhm]

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Atom

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The smallest and most basic unit of a chemical element that retains the chemical properties of that element.

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Example: This diagram shows the basic structure of an atom, with a central nucleus containing protons and neutrons, and electrons orbiting the nucleus.

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Chemical Bond Noun

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[kem-i-kuhl bond]

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Chemical Bond

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A lasting attraction between atoms, ions, or molecules that enables the formation of stable chemical compounds.

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Example: This image shows an oxygen atom sharing its electrons with two hydrogen atoms to form covalent bonds, creating a water molecule.

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Octet Rule Noun

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[ok-tet rool]

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Octet Rule

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A chemical principle stating that atoms tend to bond in a way that gives them eight electrons in their valence shell.

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Example: A sodium atom gives an electron to a chlorine atom, so both end up with a stable, full outer shell of eight electrons (an octet).

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Compound Noun

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[kom-pound]

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Compound

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A substance formed when two or more different chemical elements are chemically bonded together in a fixed ratio.

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Example: This image shows a water molecule, a compound where one oxygen atom shares electrons with two hydrogen atoms, as illustrated by the Lewis dot structure.

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Covalent Bond Noun

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[koh-vey-luhnt bond]

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Covalent Bond

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A type of chemical bond that involves the mutual sharing of one or more pairs of electrons between atoms.

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Example: Two nonmetal atoms share their outer electrons (valence electrons) to form a stable covalent bond, creating a molecule.

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Ionic Bond Noun

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[ahy-on-ik bond]

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Ionic Bond

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A chemical bond formed through electrostatic attraction between two oppositely charged ions, involving the transfer of electrons.

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Example: A sodium (Na) atom transfers its outer electron to a chlorine (Cl) atom, forming a positively charged sodium ion (Na+) and a negatively charged chlorine ion (Cl-).