Why is co placed before ni on the periodic table?

Answer 1

Keep in mind that the Atomic Mass of an element is based on an average of relative abundance of stable isotopes. Nickel has several stable isotopes and Cobalt I believe has only one stable isotope. The weighted average proportionally to the relative abundance of the several Nickel isotopes is less than the average of Cobalt's isotope(s). So basically Though Nickel has a greater atomic number and the trend is for this to correlate with atomic mass because nickel exists in relatively large proportion as a lighter stable isotope Nickels average atomic mass is less than Cobalt's atomic mass. Google about relative abundance and calculating atomic mass to find all sorts of interesting things!

Answer 2

In the Periodic Table, the elements are arranged by atomic number (number of protons), not atomic mass. The number of protons is an important factor in how an element behaves chemically.

Atomic mass is determined by number of protons plus number of neutrons in an atom. Many elements have isotopes which have different number of neutrons. Typically, the increase in atomic number will result in atomic mass increasing, but Cobalt has enough naturally occurring isotopes which make the average atomic mass is slightly higher than the average atomic mass of Nickel.

Answer 3

No. although Nickel has more protons in its nucleus, Cobalt has more neutrons on average.

Average atomic mass of Cobalt : 58.9 grams/mole

Average atomic mass of Nickel : 58.7 grams/mole

Answer 4

Elements are arranged according to atomic number.So Co is placed before Ni.

Answer 5

Co has 27 protons ans Ni has 28.So Cobalt will be before Nickel.Cobalt has less protons that why placed earlier on the table.