Elements and atoms
Draw electronic arrangement of any 5 elements with atomic
number 1-18. Follow school pattern [ tabular format as given in
the slides] .Write representation, Label them: Name of
element, symbol, atomic number, Mass number, Number
protons, electrons and neutrons, Number of valence electrons,
reactive nor reactive , gain or lose electron , ion form
Example: Sodium, atomic number 11[ subscript] , Mass number
23 [ superscript], Number of protons 11,Number of electrons
:11, Number of neutrons:12,
Number of valence electrons 1[ electrons on outer most shell],
reactive, Na+ loses 1 electron to become sodium ion .
2. Magnesium has three stable isotopes, 24Mg, 25Mg, and
26Mg, with atomic masses 23.9850 u, 24.9858 u, and 25.9826 u
respectively.
The natural abundances of 24Mg and 25Mg are 78.99% and
10.00% respectively. Calculate the average atomic mass of
magnesium.