Periodic Table Basics

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What are periodic groups?

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Periodic groups are columns in the periodic table that classify elements with similar chemical properties.

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What are periods in the periodic table?

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Periods are horizontal rows in the periodic table where elements are arranged in order of increasing atomic number.

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What are periodic trends?

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Periodic trends are patterns in the periodic table that show the variation of certain characteristics of elements, such as electronegativity, ionization energy, and atomic radius.

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Who was Mendeleev?

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Dmitri Mendeleev was a Russian chemist who created one of the first versions of the periodic table by atomic mass and he predicted the properties of undiscovered elements.

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Who was Mosely?

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Henry Moseley was an English physicist who redefined the periodic table by arranging elements in order of increasing atomic number, which resolved inconsistencies in Mendeleev's arrangement.

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What is atomic number?

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The atomic number is the number of protons in the nucleus of an atom, which determines the element's identity and its position in the periodic table.

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What is electronegativity?

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Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons. It generally increases across a period and decreases down a group in the periodic table.

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What is ionization energy?

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Ionization energy is the energy required to remove an electron from an atom in its gaseous state. It typically increases across a period and decreases down a group.

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What is atomic radius?

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Atomic radius is the distance from the nucleus of an atom to the outermost electron shell. It generally decreases across a period and increases down a group in the periodic table.

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What is a valence electron?

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A valence electron is an outer shell electron that is associated with an atom.