solution:
The quoted atomic mass on the Periodic Table is the WEIGHTED average of the individual isotopic masses. The higher the isotopic percentage, the MORE that isotope will contribute to the isotopic mass. For this reason, most masses that are quoted on the Table are non-integral.
By way of example we could look to the hydrogen atom. The VAST majority of hydrogen atoms (in this universe) are the protium isotope. i.e. 1H, whose nuclei contain JUST the defining proton. There is a smaller percentage (>1%) of hydrogen atoms WITH one NEUTRON in their nuclei to give the deuterium isotope. i.e. 2H, and because this is relatively cheap, and easily incorporated into a molecule, deuterium labelling is routinely used in analysis.
And there is even a smaller percentage of hydrogen atoms with TWO NEUTRONS in their nuclei, to give the tritium isotope. i.e. 3H. The weighted average of the isotopic percentages gives 
Answer:
Are transferred completely from the valence shell of an element to the other
Explanation:
Basically, to form a chemical bond, you either transfer or you share. When you share, it is a case of covalent bonding which can be in several other forms. When there is a transfer, it is a case of ionic bonding.
The basic explanation for this is that while some atoms are electronically sufficient, some are electronically deficient. This means while some atoms are having an excess number of electrons, then some are having less number of electrons.
To satisfy both parties, there must be a transfer if electrons between the two parties. While the one with the excess numbers serves as the donor, the one with insufficient number of electrons serve as the acceptor
<span>The rate of a chemical reaction can be increased by raising the temperature. </span>