Salsabil's Topic 1 Mindmap

Salsabil's Topic 1 Mindmap

1. Definitions

   • Isotopes are atoms of the same element that have the same number of protons and electrons but different number of neutrons.
   • Relative isotopic mass is the mass of an atom of an isotope of the element compared to 1/12 mass of an atom of carbon-12, which has a mass of 12
   • relative atomic mass of an element is the weighted mean mass of an atom of the element compared to 1/12 the mass of an atom of carbon-12, which has a mass of 12.

2. Mass Spectra

   • Ionisation: The atom or molecule is ionised by knocking one or more electrons off to give a positive ion. (By an electron gun)
   • Acceleration: The ions are accelerated so that they all have the same kinetic energy.
   • Deflection: The ions are then deflected by a magnetic field according to their masses. The lighter they are, the more they are deflected. The amount of deflection also depends on the number of positive charges on the ion
   • Detection: The beam of ions passing through the machine is detected electrically.

3. Ionisation Energy

   • First ionisation energy is the energy required to remove one mole of electrons from each atom in one mole of atoms in the gaseous state to give gaseous 1+ ions.
   • Successive ionisation energy is the energy required to remove one mole of electrons from each ion in one mole of +1 ions in gaseous state to give gaseous 2+ ions
   • Factors that affect the ionisation energy:
     • The repulsion (shielding) experienced by the electrons from ll the other electrons present
     • Nuclear charge of an atom
     • The distance/orbital in which the electron exists
   • Across a period, As you go across the period, the number of electrons increase which results in a increase in attraction between the nucleus and the electron. Therefore a decrease in in the energy in the outermost electron, and an increase in first ionisation energy.
     • The increase in nuclear charge is more significant than the increase in electron-electron repulsion. So there is a general increase in first ionisation energy
   • Down a group, one quantum shell is added on each occasion. This increases the energy in the outermost electrons for two reasons. Each shell added has a higher energy value than the last. Secondly, as each quantum shell is added, the outer electrons experience increased repulsion(shielding) from the inner electrons.