Question

Using the periodic table and your knowledge of atomic structure. cobalt (Co) and nickel (Ni) have almost identical atomic mass numbers. Comparing nickel and cobalt from the periodic table, which statement best describes the atoms?
A. Nickel has one more neutron.


B. Both atoms will have the same number of protons.


C. Both atoms will have the same number of neutrons.


D. Cobalt has one less proton.

Answer 1

Answer:

Cobalt has one less proton.

Explanation:

Nickel and Cobalt both has almost same atomic mass number approximately 59 but has different atomic number.

Number of proton and electrons in an atom is given by,

Number of proton = Number of electron = atomic number of an atom.

Number of neutron in an atom is given by,

Number of neutrons = Atomic mass number - atomic number

Case 1: Cobalt

Atomic mass number = 59

Atomic number = 27

Number of proton and electrons in Nickel is given by,

Number of proton = Number of electron = atomic number of an atom.

Number of proton = 27

Number of proton = 27

Number of neutron in an atom is given by,

Number of neutrons = Atomic mass number - atomic number

Number of neutrons = 59 - 27

Number of neutrons = 32

Case 2: Nickel

Atomic mass number = 59

Atomic number = 28

Number of proton and electrons in Nickel is given by,

Number of proton = Number of electron = atomic number of an atom.

Number of proton = 28

Number of neutron in an atom is given by,

Number of neutrons = Atomic mass number - atomic number

Number of neutrons = 59 - 28

Number of neutrons = 31

Cobalt has one less proton.

Thus, Option D is correct.

Answer 2

Answer: The correct answer is option D.

Explanation:

Cobalt and Nickel both are transition metals which means that their last electron enter d-orbitals.

These two elements have similar atomic masses but differ in the atomic number.

Atomic number is equal to the number of protons or electrons present in that element.

Atomic number = number of protons =  number of electrons

Atomic Mass is the sum of protons and neutrons in an element

Atomic mass = Number of protons + Number of neutrons

• For Cobalt:

Atomic Number = 27

Number of protons = 27

Atomic mass = 59

Number of neutrons = 59 - 27 = 32

Hence, Number of protons in this element is 27 and number of neutrons are 32.

• For Nickel:

Atomic Number = 28

Number of protons = 28

Atomic mass = 59

Number of neutrons = 59 - 28 = 31

Hence, Number of protons in this element is 28 and number of neutrons are 31.

• From the above information, it is visible that cobalt has one less proton that the nickel.

Hence, the correct answer is option D.