periodic table

Cards (24)

  • Periodic table
    An organisational tool to identify patterns and trends in, and relationships between, the structures (electronic configurations and atomic radii) and properties (electronegativity, first ionisation energy, metallic or non-metallic character and reactivity) of elements
  • Key knowledge from the study design
    • For each trend of the periodic table, you need to be able to give a definition, state the trend and explain why it increases/decreases up/down a group and period
  • Features of the periodic table

    • Arranged in order of increasing atomic number (number of protons of an element)
    • Periods (horizontal rows 1-7)
    • Groups (vertical columns 1-18)
    • Gives information about the electron configuration
    • Arranged in order of increasing valence electrons (electrons in outer shell)
    • Each element in the same period has the same number of electron shells
    • Each element on the same group has the same number of valence electrons in their outer shell
  • Tip: when working out valence e- in group 13 to 18, subtract 10
  • Periodic table blocks
    • s-block (Group 1 + 2 and He)
    • p-block (Groups 13-18 except He)
    • d-block (Groups 3-12)
    • f-block (Lanthanoids and Actinoids)
  • Highest energy subshell configurations
    1. block: s1 or s2
    2. block: s2 p1 to s2 p6
    3. block: d1 s2 to d10 s2
    4. block: 4f subshell - Lanthanoids, 5f subshell - Actinoids
  • Periodic table groups
    • Noble gases
    • Halogens
    • Non-metals
    • Alkali metals
    • Alkali Earth metals
    • Transition metals
    • Other metals
  • Core charge
    Measure of the attractive force felt by the valence electrons in the outer shell towards the nucleus
  • Determining core charge
    Core charge = number of protons - number of inner shell electrons
  • Determining core charge
    • Aluminium: Protons = 13, Inner shell electrons = 10, Core charge = 13 - 10 = +3
    Sodium (group 1): Protons = 11, Inner shell electrons = 10, Core charge = 11 - 10 = +1
    Chlorine (group 17): Protons = 17, Inner shell electrons = 10, Core charge = 17 - 10 = +7
  • Atomic size
    • Decreases across a period (electrons being added to same energy level, protons being added to nucleus, valence electrons pulled closer)
    Increases down a group (number of occupied energy levels/shells increasing)
  • Electronegativity
    Ability of an atom to attract electrons to itself
  • Electronegativity trends
    • Increases across a period (more protons in nucleus)
    Atoms on the right are close to filling their valence outer shells therefore electronegativity increases
  • Atomic radius

    Distance from the nucleus to the outermost electron shell
  • Atomic radius trends
    • Increases down a group (increase in number of electron shells)
    Decreases across a period (valence shell pulled closer to nucleus)
  • The more electrons (-) and protons (+), the larger the atomic radius
  • First ionisation energy

    Energy required to remove the first valence electron from an atom
  • Ionisation energy trends
    • Decreases down a group (electron to be removed is increasingly distant from nucleus)
    Increases across a period (more protons being added to nuclei, electrons more tightly held)
  • The further away an electron is from the nucleus, the easier it is to pull away. The lower the atomic number the higher the ionisation energy.
  • Metallic character

    Tendency of an atom to lose an electron instead of gaining an electron in order to fill its valence shell
  • Metallic character trends
    • Non-metals (on the right) have more valence electrons therefore the tendency to lose their electrons decreases
  • Reactivity of metals
    Measure of how readily an element will react with another element/lose electrons
  • Reactivity of non-metals
    Measure of how readily a non-metal atom will accept an electron
  • Atoms of non-metallic elements undergo chemical reactions to gain electrons to form a stable outer shell (octet arrangement)