Atom/Periodic Table

• Atomic Orbital


  Region in space around the nucleus of an atom in which there is a high probability of finding an electron
• Relative Atomic Mass


  Average Mass of atoms of element compared to 1/12 mass of carbon-12 isotope
• First Ionisation Energy


  Minimum energy to remove most loosely-bound electron from an isolated gaseous atom in its ground state
• Oxidation


  Loss of Electrons & Increase in Oxidation Number
• Isotopes


  Atoms of the same element with different mass numbers due to different number of neutrons OR Atoms with the same atomic number but different mass numbers
• (Atomic) Energy Level


  Fixed amount of energy of an electron in an atom
• Radioactivity


  Spontaneous breaking up of a nucleus to release alpha, beta or gamma radiation
• Atomic Radius


  Half the distance between the nuclei of two identical atoms of the same element joined by a single covalent bond
• Heisenberg's Uncertainty Principle


  It is not possible to measure the exact position & momentum of electron in atom simultaneously (at the same time)
• Alpha Particle


  Helium nucleus OR 2 protons + 2 neutrons
• Principle of Mass Spectrometry


  Positively charged ions are separated by mass when moving in a magnetic field
• Ground State


  In lowest energy state OR n=1
• Excited State


  Higher energy state OR n>1
• Atomic Number


  Number of protons in nucleus of an atom
• Radioisotope


  Radioactive isotope OR isotope with unstable nucleus
• (Energy) Sub-Level


  Sub-division of a main energy level consisting of one or more orbitals of the same energy
• Mass Number


  Number of nucleons (protons + neutrons) in the atoms of an isotope
• Half Life


  Time taken for half of the nuclei in a sample of decay OR Time taken for activity to reduce by a half
• Oxidation Number


  Charge on atom if electrons distributed by rules (if bonds assumed ionic)
• Second Ionisation Energy


  Electron removed from monopositive ion OR X^+ -> X^2+ + e-