Question

Explain the concept of multi-electron atoms.

Answer 1

Atoms with multiple electrons are a complex subject. This is due to the fact that the wavefunction for an atom with more than one electrons is a function of the positions of all of the electrons in the atom. The electrons cannot really be thought of as being indpendent from each other. They are not independent from each other at all. However, this is very very difficult to deal with. As a result, as chemists we try to simplify the problem in a way that we can wrap our head around it. One very important simplfication that we make is that even though we cannot treat each electron separate, we do. This is known as the single electron approximation. And from it we get the very useful idea of "orbitals". We imagine that each electron has its own wavefunction and since wavefunction is an odd cumbersome word we instead use "orbital". To make things even more simple we assume these orbitals are essentially the same as the solutions we had for the hydrogen atom. The only difference being the nuclear charge. So we can use the same quantum numbers that we had for electrons in hydrogen to describe the electrons in a multi-electron atom.

Answer 2

Electrons with more than one atom, such as Helium (He), and Nitrogen (N), are referred to as multi-electron atoms. Hydrogen is the only atom in the periodic table that has one electron in the orbitals under ground state. We will learn how additional electrons behave and affect a certain atom.

Let's review some basic concepts. First, electrons repel against each other. Particles with the same charge repel each other, while oppositely charged particles attract each other. For example, a proton, which is positively charged, is attracted to electrons, which are negatively charged. However, if we put two electrons together or two protons together, they will repel one another. Since neutrons lack a charge, they will neither repel nor attract protons or electrons.

(a) The two electrons are placed together and repel each other because of the same charge. 

(b) The two protons are repelling each other for the same reason. 

(c) When oppositely charged particles, an electron and a proton, are placed together, they attract each other.

Protons and neutrons are located in an atom's nucleus. Electrons float around the atom in energy levels. Energy levels consist of orbitals and sub-orbitals. The lower the energy level the electron is located at, the closer it is to nucleus. As we go down and to the right of the periodic table, the number of electrons that an element has increases. Since there are more electrons, the atom experiences greater repulsion and electrons will tend to stay as far away from each other as possible. Our main focus is what effects take place when more electrons surround the nucleus. To better understand the following concepts it is a good idea to first review quantum mechanics.

Shielding (Screening) :

With more protons in the nucleus, the attractive force for electrons to the nucleus is stronger. Thus, the orbital energy becomes more negative (less energy). Orbital energy also depends on the type of l orbital an electron is located in. The lower the number of l, the closer it is to the nucleus. For example, l=0 is the s orbital. S orbitals are closer to the nucleus than the p orbitals (l=1) that are closer to the nucleus than the d orbitals (l=2) that are closer to the f orbitals (l=3).

Penetration Penetration is the ability of an electron to get close to the nucleus. The penetration of ns > np > nd > nf. Thus, the closer the electron is to the nucleus, the higher the penetration. Electrons with higher penetration will shield outer electrons from the nucleus more effectively. The s orbital is closer to the nucleus than the p orbital. Thus, electrons in the s orbital have a higher penetration than electrons in the p orbital. That is why the s orbital electrons shield the electrons from the p orbitals. Electrons with higher penetration are closer to the nucleus than electrons with lower penetration. Electrons with lower penetration are being shielded from the nucleus more.

Comments

Electron ke pass atom hota hai ya atom ke passs electrons