atoms

atoms

1. consists of subatomic particles in

   • electron shells
     • occupied by
       • • relative mass: 1/1840 relative charge: -1
           • arrangement of electrons in shells represented by
             • electronic structure
         • that are found in valance shells
           • valance electrons
           • atoms with same number of valance shells = in the same group of PT
           • elements w fully filled valance shells= group 0 in PT, stable in electronic configuration = noble gases
   • nucleus
     • contains
       • protons(p)
         • relative mass: 1 relative charge: +1
         • have the same number of
           • isotopes
             • have same chemical properties as normal atom but physical properties different
             • that emit high energy radiation
               • radioisotopes
         • number in atoms indicated by proton number/ atomic number (Z)
           • used to represent an element
             • nucleon number (A)
               • total number of protons and neutrons
         • are equal numbers in an atom
           • electrons (e)
             • moving rapidly around electron shells around nucleus
               • first electron shell fully filled then to the second and so on
                 • 1st shell: max 2 electron 2nd shell: max 8 electron 3rd shell: max 8 electron
               • elements w same no. of electron shells= same period on PT
           • atoms are electrically neutral
       • neutrons(n)
         • relative mass: 1 relative charge: 0
         • do not have the same number of
         • no. of neutrons= atomic mass- atomic number

2. mass can be measured w Relative Atomic Mass (Ar) / Relative Molecular mass (Mr) / Relative Formula Mass (Mr)