C#3 2021

C#3 2021

1. relative charges and approximate relative masses of a proton, neutron and electron

2. structure of an atom containing protons & neutrons (nucleons) in the nucleus and electrons arrange in the shell

3. define atomic (proton) number

   • atomic number/ proton number is the number of protons in the nucleus of an atom. (each element has its own proton number)

4. define nucleon (mass) number

   • nucleon number/ mass number is the total number of protons and neutrons in an atom

5. nuclide notation

6. mass number = proton number + neutron number (mass no. = p + n). proton number = electron number (p = e). each element has its own proton number

7. an atom is electrically neutral because the number of electrons is equal to the number of protons

8. define isotopes

   • isotopes are atoms of the same element with the same atomic number and mass number
   • isotopes of the same element have the same chemical properties due to the same number of electrons (only valence electrons are involved in chemical reactions)
   • isotopes of the same element have different physical properties due to the different number of neutrons, resulting in different densities, melting & boiling points
   • uses of isotopes

9. define ions

   • an ion is a charged particle formed when an atom gains or loses electrons

10. ions

    • metals (group I, II, III) lose electrons to form positive ions (cations)
    • non-metals (group V, VI, VII) gain electrons to form negative ions (anions)
    • group IV (non-metals) share electrons to be stable
    • group 0 elements do not want to form ions bc they have a full outer sheel

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