Answer: A = atomic number = 12
Explanation: A (atomic number) defines the chemical element. It is the numbervof protons or electrons. Neutron numbers may vary, produving isotopes of differing atomic mass. This isotope has atomic mass 28. The atomic number 12 = carbon. C28 does not really exist. If it could be produced it would be radioactive with an almost zero halflife.
2 Fluorine atoms covalently bonded with each other, each sharing an equal number of a single, one valence electron to achieve a stable octet, would form a diatonic fluorine gas. It is a diatomic molecule, a molecule consisting of 2 atoms that are the same, in this case fluorine.
<u>Answer</u>:-
Name of element = Lead
Symbol ♾ of Lead = Pb
Atomic no. = 82
Atomic mass = 207.2 amu
No. of protons = 82
No. of electrons = 82
Yes, lead(Pb) is a metallic element and certainly it has 6 electron shells which means 6 energy level.
If you find anything unclear you can ask me...