Atomic Structure

Atomic Structure

1. The Atom

   • Protons
     • -Found in Nucleus -Relative Charge of +1 -Relative Mass of 1
   • Neutrons
     • -Found in Nucleus -Relative Charge: 0 -Relative Mass: 1
   • Electrons
     • -Found in orbitals around nucleus -Relative Mass: 1/1800 -Relative Charge: -1
   • Mass Number
     • Number of Protons and Neutrons in the nucleus of an atom
   • Atomic Number
     • Number of protons in the nucleus of an atom
   • Isotopes
     • Isotope: atom of the same element with same number of protons but different number of neutrons
     • Radioisotopes
       • Radioactive isotopes
       • Carbon-14
         • -Used for dating fossils -When an organism dies, CO2 is still trapped inside and decays over time -Half life = 5730 years
       • Cobalt-60
         • -Emits gamma radiation -Used in Radiotherapy -Used to sterilize medical supplies Half life = 5.27 years
       • Iodine-131 and Iodine-125
         • -Used as medical tracers -Emit gamma and beta radiation -135 has 8-day half-life and used on thyroid gland to check for hyperactivity

2. The Mass Spectrometer

   • VIADD
     • Vaporization
       • Inject a vaporised sample of substance into machine
     • Ionization
       • Atoms bombarded by electron stream from electron gun, making them all cations
     • Acceleration
       • Cations are sped up by electric field
     • Deflection
       • cations deflected onto curved path using magnetic field. All separated onto different paths according to mass:charge ratio
     • Detection
       • ions strike detector and recorded according to mass
   • Relative Atomic Mass

3. Electron Arrangement

   • Electrons are arranged in shells around the nucleus
   • Electromagnetic Spectrum
   • Spectrum
     • Continuous
       • A spectrum of radiation that consists of a continuous range of frequencies and colours
     • Line
       • A spectrum of radiation/a pattern of thin discrete lines of a different colour, each which corresponds to a specific frequency
     • Emission
       • Balmer Series
         • electrons falling to the n=2 energy level
       • Lyman Series
         • energy falling to n=1, highest energy level. Largest drop; emits UV radiation
   • Hydrogen

4. Ionization Energy

   • -The minimum energy needed to remove the most loosely held electron from 1 mole of gaseous atoms. -Successively increases with every electron removed

5. Orbitals

   • s and p orbitals

6. Aufbau, Hund and Pauli

   • Exceptions
     • Copper
       • [Ar[ 4s^1 3d^10
     • Cromium
       • [Ar] 4d^1 3d^5
   • Aufbau
     • Each sub-level is filled before going to the next level
   • Hund
     • Fill each shell individually before pairing up the electrons
   • Pauli
     • Two electrons should occupy each orbital but each must have  separate spin

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