Atoms Summary

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  • Atoms Summary
    • Calculate Ar from relative abundance data
      • The overall mass number of an element depends on;
        • The percentage abundance of the different isotopes.
          • The relative isotopic masses of the isotopes.
            • We use data from a mass spectrometer to calculate the Ar of an element
      • Mass Spectrometry tells us each relative isotopic masses and their abundancies
    • Writing Formula
      • The overall charge must be zero, so the ion charges must balance. Sum of positive charges= sum of negative charges
        • Elements are represented by their symbols
      • Charges are usually omitted from compound formula
      • Diatomic molecules are when two atoms are bonded together
        • The number of each atom, is shown in subscript. When there is multiple of a molecule, the number is put in front
          • Binary compounds are compounds thats contain two elements only. To name, use the name of the first element, then change the ending of the second element to "ide"
            • For Ionic compounds, metal ions always come first
              • State symbols must be included: S) Solid, L) liquid, G) Gas, Aq) Solute in water (Aqueous)
    • Structure
      • Ion
        • Negative ions have more electrons than protons.
        • Positive ions have less electrons than protons
        • Molecular polyatomic ions include
          • Zinc Ion Zn
          • Sulfate SO
          • Carbonate CO
          • Hydroxide OH
          • Silver ion Ag
          • Ammonium NH
          • Nitrate NO
        • Charge can be identified by group. Metals are positive. Non metals are negative
      • Atom
        • Electrons have a mass of 1/1836 and have a charge of -1, found in orbitals or energy levels
          • Orbitals take up most volume in an atom
        • Neutrons have a mass of +1 and a charge of 0, found in the nucleus
        • Protons have a mass of 1 and charge of +1, found in nucleus
        • These are uncharged as have same number of protons and electrons
        • Mass is concentrated in the nucleus where you find nucleons
        • Contains sub-atomic particles
    • Balancing Equations
    • Key Definitions
      • Relative atomic (molecular) mass-
        • Atomic masses are measured using the unified atomic mass unit, u  1 u = 1.660538782 x 10-27 kg
          • The carbon-12 isotope is  the international standard all elemental masses are measured against
          • The Ar is the weighted mean mass of an atom of an element compared to 1/12th of the mass of an atom of carbon-12
        • In comparrason to the Carbon-12 isotope
        • Relative atom mass= abundance (intensity) X mass number (M/Z= mass to charge ratio). You then add each different isotope's calculation, then divide by the total abundance.
          • All the data can be found using a Mass Spectrometer
      • Isotope:
        • These are atoms of the same element with the same number of protons but different numbers of neutrons. Also differing masses
        • Relative isotopic mass, is the mass of an isoptope compared to 1/12 of the mass of carbon-12
  • Atom
    • Electrons have a mass of 1/1836 and have a charge of -1, found in orbitals or energy levels
      • Orbitals take up most volume in an atom
    • Neutrons have a mass of +1 and a charge of 0, found in the nucleus
    • Protons have a mass of 1 and charge of +1, found in nucleus
    • These are uncharged as have same number of protons and electrons
    • Mass is concentrated in the nucleus where you find nucleons
    • Contains sub-atomic particles

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