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Chemistry

  • IGCSE Edexcel
  • Revision Notes

1. Principles of Chemistry

1.2 Elements, Compounds & Mixtures>1.3 Atomic Structure>1.4 The Periodic Table>1.5 Chemical Formulae, Equations and Calculations>1.6 Ionic Bonding>1.7 Covalent Bonding>1.8 Metallic Bonding>1.9 Electrolysis>

2.1 Group 1 (Alkali Metals) – Lithium, Sodium and Potassium >2.2 Group 7 (Halogens) – Chlorine, Bromine and Iodine >2.3 Gases in the Atmosphere >2.4 Reactivity Series >2.5 Extraction and Uses of Metals >2.6 Acids, Alkalis and Titrations >2.7 Acids, Bases and Salt Preparations >2.8 Chemical Tests >

3.1 Energetics >3.2 Rates of Reaction >3.3 Reversible Reactions and Equilibria >

4.1 Introduction >4.2 Crude Oil >4.3 Alkanes >4.4 Alkenes >4.5 Alcohols >4.6 Carboxylic Acids >4.7 Esters >4.8 Synthetic Polymers >

1.4 The Periodic Table

1.4.1 Understand how elements are arranged in the Periodic Table:

  • In order of atomic number
  • In groups and periods.

Elements on the periodic table are arranged in order of increasing atomic number.

GROUPS

  • Vertical columns in the table
  • Group number shows the number of valence (outermost shell) electrons
    • E.g. elements in group 2 have 2 electrons in the valence shell
  • The final group is called group 18 or 8 or 0

PERIODS

  • Horizontal rows in the table
  • Period number shows the number of electron shells in an atom
    • E.g. elements in period 2 have two electron shells

1.4.2 Understand how to deduce the electronic configurations of the first 20 elements from their positions in the Periodic Table

Deducing total number of electrons

  • Number of electron = number of proton = atomic number (for an atom)

Each electron shell can accommodate a fixed number of electrons

  • 1st shell: 2 electrons
  • 2nd shell: 8 electrons
  • 3rd shell: 8 electrons

Electronic Configuration of First 20 Elements

1.4.3 Understand how to use electrical conductivity and the acid-base character of oxides to classify elements as metals or non-metals

1.4.4 Identify an element as a metal or a non-metal according to its position in the Periodic Table

In general,

  • Metals are on the left of the periodic table
  • Non-metals are on the right of the periodic table
  • They are separated by metalloids (semimetals) which form a zig-zag line

1.4.5 Understand how the electronic configuration of a main group element is related to its position in the Periodic Table

Period number: number of electron shells

Group number: number of electrons in the outer shell

1.4.6 Understand why elements in the same group of the Periodic Table have similar chemical properties

  • The chemical properties of an element depend on the number of electrons in the outer shell
  • Elements in the same group have same number of electrons in the outer shell
  • Therefore, elements in the same group have similar chemical properties

1.4.7 Understand why the noble gases (Group 0) do not readily react

  • Noble gases (group 0) have 8 electrons in their outer shell (except for helium, which has 2)
  • Noble gases reach octet rule, meaning that they have full electron shells
  • They do not lose or gain electrons easily
  • Therefore, they are unreactive and do not easily form molecules

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