Atomic Structures & Electron configurations

Atomic Structures & Electron configurations

1. Definitions

   • Atomic Number (Z): The number of protons in the nucleus.
   • Mass Number (Ar): The number of protons and neutrons in the nucleus.
   • Isotope: Atoms of an element with a different number of neutrons.
   • Relative atomic mass: The average mass of an atom compared to 1/12th the mass of an atom of carbon-12
   • Relative: compared to 1/12th of mass of an atom of carbon-12 ( any definition with relative in requires this.
   • Relative isotopic mass: the average mass of a isotope of an atom compared to 1/12th the mass of an atom of carbon-12
   • Relative molecular mass: the average mass of a molecule compared to 1/12th the mass of an atom of carbon-12
   • Relative formula mass: the average mass of the simplest whole number formula of a compound compared to 1/12 the mass of an atom od carbon-12
   • First ionisation energy: the minimum energy required to remove an electron from each of one mole of atoms in the gaseous state to form 1+ ions
   • Second & successive ionisation energy: The minimum energy required to remove an electron from each of one mole of 1+ ions in the gaseous state to form 2+ ions
   • Atomic Orbital: region within an atom that can hold up to 2 electrons

2. Atomic Mass calculations

3. Ionisation Energy

   • Down the group
     • Nuclear charge increases
     • Atomic radius increases
     • Shielding increases
     • Electrostatic attraction decreases

4. Electron Configurations

   • Filling order
     • 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6
     • Cr : 1s2 2s2 2p6 3s2 3p6 4s1 3d5
     • Cu : 1s2 2s2 2p6 3s2 3p6 4s1 3d10