Protons & Position on the Periodic Table

Specification Point 1.16:
  • Explain the meaning of the atomic number of an element in terms of position in the periodic table and number of protons in the nucleus.
  • We have previously seen that the atomic number (proton number) of an element is equal to the number of protons in its nucleus.
  • The atomic number also forms the basis for the design of the Periodic Table.
  • Elements are arranged on the Periodic Table in order of ascending atomic number, where each element has one proton more than the element preceding it.
  • The table is arranged in vertical columns called Groups numbered 1 – 8 and in rows called Periods.
  • Elements in the same Group have the same number of outer shell electrons and thus have similar chemical properties.

Groups & Periods

Specification Point 1.17:
  • Describe in the periodic table:
    a) elements that are arranged in order of increasing atomic number, in rows called periods
    b) elements with similar properties that are placed in the same vertical columns called groups
  • Period: these are the horizontal rows that show the number of shells of electrons an atom has.
    • E.g. elements in Period 2 have two electron shells, elements in Period 3 have three electron shells.
  • Group: these are the vertical columns that show how many outer electrons each atom has.
    • E.g. Group 4 elements have atoms with 4 electrons in the outermost shell, Group 6 elements have atoms with 6 electrons in the outermost shell.

Metals & Nonmetals

Specification Point 1.18:
  • Identify elements as metals or non-metals according to their position in the periodic table, explaining this division in terms of the atomic structure of the elements.
  • Most elements are metals which occur on the left-hand side of the Periodic table.
  • Nonmetals appear on the right-hand side.
  • The metallic character of the elements decreases as you move across a Period on the Periodic table, from left to right, and it increases as you move down a Group.
  • This trend occurs due to atoms more readily accepting electrons to fill their shells rather than losing them to have the below, already full, electron shell as their outer shell.
  • Between the metals and the nonmetals lie the elements which display some properties of both.
  • These elements are referred to as metalloids or semi-metals.

Properties of metals and nonmetals

Properties of metals and nonmetals, Edexcel GCSE Chemistry
Metals, Nonmetals and Metalloids PT, Edexcel GCSE Chemistry

A zig-zag line on this Periodic Table separates the metals from the non-metals

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Morgan Curtin Chemistry

Author: Morgan

Morgan’s passion for the Periodic Table begun on his 10th birthday when he received his first Chemistry set. After studying the subject at university he went on to become a fully fledged Chemistry teacher, and now works in an international school in Madrid! In his spare time he helps create our fantastic resources to help you ace your exams.