Ionization Energy

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Ionization Energy Noun

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[eye-on-ih-zay-shun en-er-jee]

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Ionization Energy

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The minimum amount of energy required to remove the most loosely bound electron from an isolated gaseous atom or ion.

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Example: This diagram shows an electron being removed from an atom, which requires a specific amount of energy called ionization energy.

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Cation Noun

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[kat-eye-on]

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Cation

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A positively charged ion that is formed when a neutral atom loses one or more of its valence electrons.

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Example: A neutral sodium atom loses its single valence electron, resulting in more protons than electrons, thus forming a positively charged sodium ion (cation).

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Nuclear Charge Noun

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[noo-klee-er charj]

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Nuclear Charge

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The total positive charge of an atomic nucleus, which is equal to the number of protons within the nucleus.

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Example: The green protons in the central nucleus create a positive 'nuclear charge' that attracts the negative red electrons orbiting it.

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Atomic Radius Noun

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[uh-tom-ik ray-dee-us]

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Atomic Radius

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A measure of the size of an atom, typically the mean distance from the nucleus to the outermost electron shell.

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Example: This diagram shows a sodium atom with three electron shells. Its large size, or atomic radius, is due to these multiple shells, which places the outermost electron far from the nucleus.

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Valence Electron Noun

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[vay-lence ee-lek-tron]

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Valence Electron

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An electron in the outermost shell of an atom that can participate in the formation of a chemical bond.

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Example: This diagram of an oxygen atom shows six electrons in the outermost shell; these are the valence electrons that can be removed by ionization energy.

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Coulombic Attraction Noun

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[koo-lom-ik uh-trak-shun]

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Coulombic Attraction

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The electrostatic force of attraction between oppositely charged particles, such as the nucleus and its surrounding electrons in an atom.

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Example: This diagram shows that an atom's nucleus has positive protons and is surrounded by negative electrons; the attraction between these opposite charges is Coulombic attraction.

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Period Noun

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[peer-ee-ud]

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Period

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A horizontal row in the periodic table where all elements have the same number of principal electron energy shells.

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Example: This image incorrectly depicts a biological period (menstruation), not a chemical period (a row in the periodic table) relevant to ionization energy.

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Group Noun

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[groop]

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Group

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A vertical column in the periodic table containing elements with the same number of valence electrons and similar chemical properties.

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Example: This diagram shows that groups are the vertical columns in the periodic table, such as the Alkali metals (Group 1) and Halogens (Group 17).

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Subsequent Ionization Energy Noun

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[sub-si-kwent eye-on-ih-zay-shun en-er-jee]

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Subsequent Ionization Energy

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The energy required to remove additional electrons one by one from a positive ion after the first electron is removed.

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Example: This graph shows that removing each additional electron from a chlorine atom requires more energy, with large jumps in energy when starting to remove electrons from a new, inner shell.

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Electronegativity Noun

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[ee-lek-tro-neg-uh-tiv-i-tee]

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Electronegativity

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A chemical property that describes the tendency of an atom to attract a shared pair of electrons towards itself.

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Example: This periodic table chart shows the trend of electronegativity. Elements on the right side, like Fluorine (F), are red and have high values, meaning they strongly attract electrons.