The Periodic Table - Chapter 4

• detection

  the beam of ions passing through the machine is detected electrically on a computer
• deflection

  ions are made to move in a curved paths and are deflected by a magnetic field according to their masses (the lighter they are the more they are deflected)
• acceleration

  positive ions pass between a series of negatively charged plates, the ions are accelerated so that they all have the same kinetic energy
• ionisation

  the atom is ionised by knocking one or more electrons off to give a positive ion
• vaporisation

  small amount of gas/liquid is injected into an instrument under vacuum
• pauli exclusion principle

  no more than 2 electrons may occupy an orbital and they must have opposite spin
• hund's rule of maximum multiplicity

  when two or more orbitals of equal energy are available, the electrons occupy them singly before filling them in pairs
• aufbau principle

  when building up the electron configuration of an atom in its ground state, the electrons occupy the lowest available energy levels
• electron configuration

  shows the arrangement of electrons in an atom of an element
• uses of mass spectrometry

  identify presence of isotopes and measure relative abundances / measure relative atomic and molecular masses / identify unknown compounds / used with gas chromatography to detect banned drugs
• 5 processes that occur in a mass spectrometer

  vaporisation, ionisation, acceleration, separation in a magnetic field, detection
• principle of mass spectrometry


  charged particles moving in a magnetic field are deflected to different extents according to their masses and are thus separated according to these masses
• relative atomic / molecular mass

  the average of one molecule of that element / compound compared with one twelfth the mass of one atom of the carbon-12 isotope
• isotopes

  atoms of the same element which have different mass numbers due to the different numbers of neutrons in the nucleus
• mass number

  the sum of the number of protons and neutrons in the nucleus of an atom of that element
• modern periodic law


  when elements are arranged in order of increasing atomic number, the properties of the elements recur periodically
• modern periodic table

  an arrangement of elements in order of increasing atomic number
• atomic number

  the number of protons in the nucleus of that atom
• Mendeleev's periodic law

  when elements are arranged in order of increasing atomic weight (relative atomic mass), the properties of the elements recur periodically
• Newland's octaves

  the arrangement of elements in which the first and the eighth element, counting from a particular element, have similar properties
• triad

  group of three elements with similar chemical properties in which the atomic weight (relative atomic mass) of the middle element is approximately equal to the average of the other two
• element

  a pure substance that cannot be split into simpler substances by chemical means