Question

Copper has an atomic number of 29 and a mass number of 64. what would result if an uncharged copper atom lost two electrons?

Answer 1

Explanation:

Atomic number is defined as the sum of total number of protons present in an atom. Whereas mass number is the sum of total number of both protons and neutrons present in an element.

When an atom is neutral in nature then its number of electrons are the same as its number of protons.

For example, atomic number of copper is 29 so it has 29 electrons.

When this copper atom loses two electrons then it acquires a +2 charge and results in the formation of a cation which is $Cu^{2+}$.

Thus, we can conclude that when an uncharged copper atom loses two electrons then it results into $Cu^{2+}$ ion.

Answer 2

The atomic mass of an element is the number of times of an atom of that element is  heavier than an atom of carbon taken as 12. In simpler way, atomic mass is number of protons present in  nucleus of an atom, which is a characteristic of an chemical element and is determines place of the element in the periodic table.  Mass number is total number of protons and neutrons. If an uncharged atom looses electron from its outermost shell, it becomes cation, which is positively charged species. Atomic number and mass number do not change if electron goes out of an atom.

Uncharged copper after loosing two electrons is converted to $Cu^{2+}$ which can be represented as follows:

$Cu_{29} ^{64}$→$Cu^{2+}$