Classification of the Elements

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Valence Electrons Noun

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[vay-luhns ih-lek-trons]

Back

Valence Electrons

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Electrons in the outermost energy level of an atom that are involved in forming chemical bonds and determining chemical properties.

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Example: This Bohr model of a Sodium atom shows electrons in shells; the single electron in the outermost shell is its one valence electron.

Front

Electron Configuration Noun

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[ih-lek-tron kuhn-fig-yuh-rey-shuhn]

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Electron Configuration

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The specific arrangement and distribution of electrons within the orbitals of an atom or molecule, dictating its chemical behavior.

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Example: This diagram shows how electrons are arranged in specific energy levels, or shells, around an atom's nucleus, which defines the element's electron configuration.

Front

Group Noun

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[groop]

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Group

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A vertical column in the periodic table where elements share similar chemical properties due to having the same valence electrons.

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Example: This diagram of the periodic table shows that a 'Group' is a vertical column of elements, as indicated by the downward-pointing arrows.

Front

Period Noun

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[peer-ee-uhd]

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Period

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

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Example: A period is a horizontal row of elements in the periodic table, as indicated by the label 'PERIODS' and the numbers 1 through 7.

Front

Electron-Dot Structure Noun

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[ih-lek-tron dot struhk-cher]

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Electron-Dot Structure

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A diagram that uses dots to represent the valence electrons of an atom around the element's chemical symbol.

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Example: This chart shows electron-dot structures for several elements, arranged by their group on the periodic table. The number of dots (valence electrons) matches the group number.

Front

s-Block Elements Noun

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[es-blok el-uh-muhnts]

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s-Block Elements

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The elements in Groups 1 and 2 of the periodic table, characterized by having their highest-energy electron in an s orbital.

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Example: This diagram shows the periodic table and highlights the s-block elements, which are found in the first two columns (Groups 1 and 2) and Helium.

Front

p-Block Elements Noun

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[pee-blok el-uh-muhnts]

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p-Block Elements

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The elements in Groups 13-18 of the periodic table, where the highest-energy electron occupies a p orbital.

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Example: This periodic table diagram uses color-coding to highlight the p-block elements (in yellow), showing their specific location in groups 13 through 18.

Front

d-Block Elements Noun

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[dee-blok el-uh-muhnts]

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d-Block Elements

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The elements in Groups 3-12, also known as transition metals, with their highest-energy electron occupying a d orbital.

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Example: This image shows the section of the periodic table containing the d-block elements, also known as transition metals, grouped by their shared chemical properties.

Front

f-Block Elements Noun

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[ef-blok el-uh-muhnts]

Back

f-Block Elements

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The elements in the lanthanide and actinide series, where the highest-energy electron occupies an f orbital.

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Example: This diagram of the periodic table shows the location of the f-block elements, also called the 'Inner Transition Elements', which are usually placed below the main table.

Front

Representative Elements Noun

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[rep-ri-zen-tuh-tiv el-uh-muhnts]

Back

Representative Elements

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The elements located in the s-block and p-block of the periodic table, which exhibit a wide range of properties.

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Example: This periodic table highlights the representative elements, which are found in the s-block (Groups 1A-2A) and p-block (Groups 3A-8A) of the table.