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Chemistry vocabulary · Atoms and the Periodic Table

Periodic table

Meaning in chemistry, with examples

nounCore term

In chemistry, periodic table means: A chart that arranges all known elements in order of atomic number, in rows called periods and columns called groups. Elements in the same group behave in similar ways.

In Turkish: periyodik tablo, periyodik sistem

How it is used

Students and chemists use it daily to find symbols, atomic masses and trends. You say an element is 'in group 1' or 'in period 3', and describe trends 'across a period' (left to right) and 'down a group' (top to bottom).

Example sentences

  1. Atomic radius decreases across a period of the periodic table.

  2. Check the periodic table on the wall for the atomic mass of chlorine.

Common collocations

  • on the periodic table
  • group of the periodic table
  • periodic trend
  • across a period
  • down a group
  • elementA pure substance made of only one kind of atom, all with the same number of protons. It cannot be broken down into simpler substances by chemical reactions.
  • atomic numberThe number of protons in the nucleus of an atom. It identifies the element: every carbon atom has 6 protons and every oxygen atom has 8.
  • electron configurationThe way an atom's electrons are arranged in shells and orbitals, written for example as 1s² 2s² 2p⁶ 3s¹ for sodium.
  • transition metalA metal from the central block of the periodic table, usually taken as groups 3 to 12, such as iron, copper, nickel and platinum. Many form colored compounds and have several oxidation states.
  • electronegativityA measure of how strongly an atom pulls shared electrons toward itself in a bond. Fluorine has the highest value, about 4.0 on the Pauling scale.

More terms: Atoms and the Periodic Table

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