Question Video: Explaining the Reactions of an Element With Three Outer Shell Electrons | Nagwa Question Video: Explaining the Reactions of an Element With Three Outer Shell Electrons | Nagwa

Question Video: Explaining the Reactions of an Element With Three Outer Shell Electrons Science • First Year of Preparatory School

Join Nagwa Classes

Attend live Science sessions on Nagwa Classes to learn more about this topic from an expert teacher!

Typically, how might an element with 3 electrons in its outermost energy level behave in a reaction?

03:48

Video Transcript

Typically, how might an element with three electrons in its outermost energy level behave in a reaction?

We are asked about an element which has three electrons in its outermost energy level. We need to describe how such an element would behave in a chemical reaction. Let’s start by drawing a diagram to show the electron placement or electronic configuration of an atom of this element. We know atoms have a nucleus with protons and neutrons. In this case, we do not know how many of each subatomic particle there are in the nucleus, nor do we know how many electrons an atom of this element has or how many electron shells are filled. So, for simplicity, let us draw just three energy levels.

We do, however, know that an atom has an equal number of protons and electrons, making it neutral. And we know that there are three electrons in its outer shell. We know that all inner shells are full. The full electronic configuration of this atom is shown here. But remember, there are other possible electronic configurations if we add more inner shells. Again, we do not know how many inner shells there are in this atom. We have just chosen to work with two inner shells.

Now, metal atoms tend to have one, two, or three electrons in their outer shell, and nonmetal atoms tend to have five, six, or seven electrons in their outer shell. Atoms that have less than eight electrons in their outer shell are unstable. Helium, however, is stable even though it has less than eight electrons, since its outer shell is full with two electrons. We can deduce that the element in question must be a metal since we are told it has three outer electrons. Except for the noble gas atoms, which tend to be unreactive, atoms tend to lose or gain electrons in a chemical reaction and usually end up with eight electrons in their outer shell. When there are eight electrons in the outer shell, an atom is stable, like the noble gases.

In this question, we have a metal atom. Metal atoms tend to lose all their outer electrons in chemical reactions and end up with the electronic configuration of a noble gas. Nonmetal atoms do the opposite; they gain electrons. So, we know this metal atom will lose outer electrons. But how many electrons will an atom of this element lose? We said they will lose all their outer electrons. So, it will lose all three of its outer electrons.

Now, the number of protons is no longer equal to the number of electrons, but there are three more protons than electrons. A positively charged particle will form, with a plus three charge. We call this particle an ion. An ion is a particle with an unequal number of protons and electrons. So, how does an element with three electrons in its outer energy level behave? The answer is it loses its three electrons and changes to a positive ion.

Join Nagwa Classes

Attend live sessions on Nagwa Classes to boost your learning with guidance and advice from an expert teacher!

  • Interactive Sessions
  • Chat & Messaging
  • Realistic Exam Questions

Nagwa uses cookies to ensure you get the best experience on our website. Learn more about our Privacy Policy