Doc Brown's Chemistry AQA GCSE Science-CHEMISTRY 3 Revision Notes

Chemistry Unit C3.1 The periodic table  Study Notes

CHEMISTRY UNIT 3 Chemistry 3 for GCSE Triple Award Science or GCSE Chemistry

REVISION NOTES GUIDE SUMMARY: What do you need to know for the examinations? What do you need to able to do in the exams? In AQA GCSE Science A examinations HT means for higher tier students only. Sorry, but I don't have much time to answer questions, but if you see any apparent errors or wish to comment, please email me. All my notes, learning objectives, comments for exam revision are based on the official AQA GCSE Science A Key Stage 4 syllabus specification.

  • Throughout this unit you will be expected to write word equations for reactions specified.

  • Higher tier (HT) candidates will also be expected to write and balance symbol equations for reactions specified throughout the unit.

AQA GCSE Science CHEMISTRY Unit C3.1 The periodic table

  • The modern periodic table has been developed from work begun by Newlands and Mendeleev.

  • There are trends in chemical properties within the periodic table linked to how easily the element gains or loses electrons.

  • You should use your skills, knowledge and understanding to:

    • evaluate the work of Newlands and Mendeleev in terms of their contributions to the development of the modern periodic table

    • explain why scientists regarded a periodic table of the elements first as a curiosity, then as a useful tool and finally as an important summary of the structure of atoms.

  • Knowledge of the history of the periodic table is limited to that specified in the subject content.

  • You may consider other models, but knowledge is limited to the work of Newlands and Mendeleev.

  • Examination questions may give information about other models so that comparisons can be made.

    Periodic Table Notes - an overview

AQA GCSE Science CHEMISTRY Unit C3.1.1 The early periodic table

  • a) Know that Newlands, and then Mendeleev, attempted to classify the elements by arranging them in order of their atomic weights.

    • The list can be arranged in a table so that elements with similar properties are in columns, known as groups.

    • The table is called a periodic table because similar properties occur at regular intervals.

  • b) Know and understand that the early periodic tables were incomplete and some elements were placed in inappropriate groups if the strict order of atomic weights was followed.

AQA GCSE Science CHEMISTRY Unit C3.1.2 The modern periodic table

  • a) Know that when electrons, protons and neutrons were discovered early in the 20th century, the periodic table was then arranged in order of atomic (proton) numbers.

    • Understand that when this was done, all elements could now be placed in appropriate groups.

  •  b) The modern periodic table can be seen as an arrangement of the elements in terms of their electronic structures.

    • Know and understand that elements in the same group have the same number of electrons in their highest occupied energy level (outer shell).

    • The periodic table that will be used in the examinations is on the Data Sheet, with main groups numbered from 1 to 7 and the noble gases as Group 0.

    • You are not expected to know detailed electronic configurations for elements beyond calcium, but should understand that the number of electrons in the highest occupied energy level (outer shell) for elements in the main groups is equal to the group number (except in Group 0 below helium, there are 8 electrons in the outer shell) eg. eg 1 for the Group I Alkali Metals or 7 for the Group VII Halogens


AQA GCSE Science CHEMISTRY Unit C3.1.3 Trends within the periodic table

  • a) Know that the elements in Group 1 of the periodic table are known as the alkali metals and know:

    • They are metals with low density (the first three elements in the group are less dense than water).

    • They react with non-metals to form ionic compounds in which the metal ion carries a charge of +1.

    • Their compounds are usually white solids that dissolve in water to form colourless solutions.

    • They react with water, releasing hydrogen.

    • They form white solid hydroxides that dissolve in water to give alkaline solutions.

  • b) Know that in Group 1, the further down the group an element is:

    • the more reactive the element

    • the lower its melting point and boiling point.

  • c) Know that compared with the elements in Group 1, transition elements:

    • have higher melting points (except for mercury) and higher densities

    • are stronger and harder

    • are much less reactive and so do not react as vigorously with water or oxygen.

  • d) Know that many transition elements have ions with different charges, form coloured compounds and are useful as catalysts.

  • e) Know that the elements in Group 7 of the periodic table (known as the halogens) react with metals to form ionic compounds in which the halide ion carries a charge of 1.

  • f) Know that in Group 7, the further down the group an element is:

  • g) Know and understand that a more reactive halogen can displace a less reactive halogen from an aqueous solution of its salt.

  • h) HT only: Know and understand that the trends in reactivity within groups in the periodic table can be explained because the higher the energy level of the outer electrons:

    • the more easily electrons are lost eg when Group 1 alkali metals react, more reactive down the group

    • the less easily electrons are gained eg Group 7 halogens become less reactive down the group


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