This exercise will lead you to verify that the average atomic mass of magnesium is 24.31 amu, based on the following information: isotope mass (amu) percent abundance
24Mg 23.985042 78.99%
25Mg 24.985837 10.00%
26Mg 25.982593 11.01%
The average atomic mass is the weighted average of the atomic masses of all isotopes.
What is the fractional abundance of 24Mg?

"the periodic table is arranged in order of atomic number."

answer:

the answer is 6 valence electrons.

explanation:

valence is the # of electrons on the outer most shell of an atom.

oxygen has 6.

although, the valency of oxygen is 2, because it only needs to make 2 covalent bonds, or gain 2 electrons, to achieve the stable octet configuration of a noble gas.

that's it!

if you need further assistance, let me know: )

~ trueboss72

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.