How many electrons, protons and neutrons that the element barium with atomic number of 56 and atomic mass of 137; and what ions will barium form?
The correct answer and explanation is:
Barium (Ba) has an atomic number of 56 and an atomic mass of 137. Here’s how to determine the number of electrons, protons, and neutrons:
- Protons: The atomic number of an element is equal to the number of protons in its nucleus. Since barium has an atomic number of 56, it has 56 protons.
- Electrons: In a neutral atom, the number of electrons is equal to the number of protons. Therefore, barium also has 56 electrons in its neutral state.
- Neutrons: The number of neutrons in an atom can be determined by subtracting the atomic number from the atomic mass. The atomic mass of barium is 137, and the atomic number is 56, so: Neutrons=Atomic mass−Atomic number=137−56=81\text{Neutrons} = \text{Atomic mass} – \text{Atomic number} = 137 – 56 = 81 Therefore, barium has 81 neutrons.
Ions Barium Can Form:
Barium, like many alkaline earth metals, tends to lose two electrons to achieve a stable electron configuration. This is because it has two valence electrons in the outermost shell, and by losing these electrons, it can attain the same electron configuration as the nearest noble gas, xenon.
When barium loses two electrons, it forms a Barium ion (Ba²⁺). The resulting ion has a charge of +2 because the number of protons (56) exceeds the number of electrons (54).
Explanation:
Barium is in Group 2 of the periodic table, which means it is an alkaline earth metal. These metals have two electrons in their outermost shell. Since barium’s outermost electrons are not tightly bound to the nucleus, it is energetically favorable for barium to lose these two electrons. By doing so, barium becomes positively charged and forms the Ba²⁺ ion. This ion is stable because it has the same electron configuration as xenon, a noble gas. Therefore, barium typically forms Ba²⁺ ions when it reacts with other elements.