1.4 Periodic Table

• The Periodic Table is a handy tool when studying chemistry
• It shows all of the 118 elements known to man and information about them
• The first Periodic Table was created by Dmitri Mendeleevin


  1869
• Chemical families


  Groups of similar elements organised in the Periodic Table
• Atomic number


  The number of protons in the nuclei of the atom
• Periodic Table arrangement

  • Elements arranged in order of atomic number
  • Columns called groups
  • Rows known as periods
• The first period contains helium and hydrogen
• Periodic Table information

  • Atomic Number
  • Name
  • Symbol
  • Atomic Weight
  • Electrons per shell
  • State of matter
  • Subcategory in the metal-metalloid-nonmetal trend
• Symbol


  One or two letters representing an element
• Atomic mass number


  The number of protons and neutrons in the nucleus of the atom
• Atomic number


  The number of protons only within the nucleus of the atom
• Calculating number of neutrons

  Number of neutrons = atomic mass number - atomic number
• The image shows a drawing of an atom with a nucleus in the centre and electrons moving in elliptical paths around
• Energy levels


  Fixed distances where electrons orbit the nucleus
• Electronic configuration


  The arrangement of electrons in an atom
• There must be no more than two electrons on the first energy level and no more than eight electrons on the energy levels above that
• Elements in the same group in the Periodic Table have the same number of electrons in their outer shell
• The number of electrons in the outer shell is the same as the group number for Groups 1 to 7
• Elements in the same group of the Periodic Table have similar chemical properties
• Noble gases


  Elements in group 8 or group 0 with a full outer shell
• Noble gases are very unreactive
• Metals


  Elements found on the left-hand side of the Periodic Table
• Non-metals


  Elements found on the right-hand side of the Periodic Table
• Metalloids


  Elements that show properties common to both metals and non-metals
• Differences between metals and non-metals

  • Electrical conductivity
  • Acid-base character of their oxides
• Metals can conduct electricity due to delocalised electrons
• Non-metals do not conduct electricity as they rarely contain free electrons
• Properties of non-metals

  • Low melting and boiling points
  • Brittle when solid
  • Can form ionic and covalent compounds
  • Tend to form negative ions
  • Do not shine as much as metals
  • Do not usually conduct electricity
  • Poor conductors of heat
• Properties of metals

  • High melting and boiling points
  • Good conductors of electricity and heat
  • Able to form ionic compounds
  • Form positive ions
  • Shiny when polished
  • Malleable
  • Ductile
• How are elements arranged in the Periodic Table?

  By atomic number, in groups and periods.
• What is the electronic configuration of chlorine?

  [2,8,7].
• What does the atomic mass number represent?

  The sum of protons and neutrons in an atom.
• Why do elements in the same group have similar chemical properties?

  They have the same number of electrons in their outer shell.
• Why are noble gases unreactive?

  They have full outer electron shells.
• Name two properties of metals.

  High melting points, good conductors of electricity.
• What type of oxides do metals form?

  Basic oxides.
• Why can metals conduct electricity?

  Due to the presence of delocalized electrons that can move and carry a current.
• Groups (columns) have similar chemical properties because they all have the same number of valence electrons.
• Periods (rows) have different chemical properties because they have different numbers of shells.
• The reactivity series is an arrangement of metals from most reactive at the top to least reactive at the bottom.