What is the mass number of an atom or ion with three protons, three neutrons, and three electrons?.

Its nucleus also contains two neutrons. Since 2+2=4, we know that the mass number of the helium atom is 4. Finally, the helium atom also contains two electrons, since the number of electrons must equal the number of protons.

Explanation:

Name lithium

Symbol Li

Protons 3

Neutron 4

Electrons 3

Answer : The mass of an atom is, 6

Explanation:

For the neutral atom, the number of protons and electrons are equal. But, they are unequal when the atoms present in the form of ions or the atom has some charges.

When an unequal number of electrons and protons then it leads to the formation of ionic species.

Ion : An ion is formed when an atom looses or gains electron.

When an atom looses electrons, it will form a positive ion known as cation.

When an atom gains electrons, it will form a negative ion known as anion.

Atomic number is defined as the number of protons or number of electrons.

Atomic number = number of protons = number of electrons

Mass number is defined as the sum of number of protons and number of neutrons.

Number of neutrons = Mass number - Number of protons

As we are given:

Number of protons = 3

Number of neutrons = 3

Number of electrons = 3

Mass number = Number of neutrons + Number of protons

Mass number = 3 + 3

Mass number = 6

Thus, the mass of an atom is, 6