# The respective masses in amu of the proton, the neutron, and the nckel-60 atom are 1.00728, 1.00867, and 59.9308. What is the mass defect of the nickel-60 atom in g?

##### 2 Answers

#### Explanation:

You're looking for **mass defect**, *difference* that exists between the atomic mass of a nucleus and the **total mass** of its nucleons, i.e. of its protons and neutrons.

The idea here is that the **energy** that is *released* when the nucleus is formed will **decrease** its mass as described by Albert Einstein's famous equation

In this regard, you can say that the actual mass of the nucleus will always be **lower** than the added mass of its nucleons.

Your goal here is to figure out the **total mass** of the protons and neutrons that make up a nickel-60 nucleus and subtract it from the known atomic mass of the nucleus.

Grab a periodic table and look for *nickel*, *atomic number*, **protons**.

The nickel-60 isotope has a *mass number*,

#A = Z + "no. of neutrons"#

#"no. of neutrons" = 60 - 28 = "32 neutrons"#

So, the total mass of the *protons* will be

#m_"protons" = 28 xx "1.00728 u" = "28.20384 u"#

The total mass of the *neutrons* will be

#m_"neutrons" = 32 xx "1.00867 u" = "32.27744 u"#

The **total mass** of the nucleuons will be

#m_"total" = m_"protons" + m_"neutrons"#

#m_"total" = "28.20384 u" + "32.27744 u" = "60.48128 u"#

The mass defect will be equal to

#Deltam = m_"total" - m_"actual"#

#Deltam = "60.48128 u" - "59.9308 u" = "0.55048 u"#

Now, to express this in *grams*, use the definition of the unified atomic mass unit,

#color(purple)(|bar(ul(color(white)(a/a)color(black)("1 u" = 1.660539 * 10^(-24)"g")color(white)(a/a)|)))#

In your case, you will have

#0.55048 color(red)(cancel(color(black)("u"))) * (1.660539 * 10^(-24)"g")/(1color(red)(cancel(color(black)("u")))) = color(green)(|bar(ul(color(white)(a/a)color(black)(9.1409 * 10^(-25)"g")color(white)(a/a)|)))#

The mass defect is

#### Explanation:

Mass defect is the amount of mass that is lost when protons and neutrons combine to form a nucleus. The protons and neutrons become bound to each other, and the binding energy that's released shows up as mass being lost because of the relation

Nickel-60 has a mass number of 60 and an atomic number of 28, thus 28 protons and 32 neutrons are bound together. The mass of the geee particles is given by:

Compare that with the given atomic mass of nickel-60

Mass defect =

Note the units. To get grams per *atom* divide by Avogadro's Number:

Go back to the molar basis and see how much energy this is in

This is tremendously larger than the energy changes associated in chemical reactions. This shows the potential power of the nuclear force and processes based on it.