# Why are the electrons in an atom moving around the nucleus?

Asked by Christian95 (3260) December 28th, 2009

Is it because of the electro-magnetic forces or because of the nuclear forces?I’d like a full explanation about how the movement happens

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Electrons are trapped in orbit around the nucleus of an atom due to nuclear forces of attraction. They are always on the move.

Kelly_Obrien (1735)

sndfreQ (11739)

@Medlang I don’t want a very complicated explanation I want just something easy to understand not an article copied here

Christian95 (3260)

electrons=negative charge
protons=positive charge

Protons are in the nucleus, electrons’ charge causes attraction that is electromagnetic, gravitational, and “weak force” attraction.

sndfreQ (11739)

Simplest explanation that I can give you: Electrons are attracted and held near the nucleus of the atom by an electromagnetic force known as Coulombic Force. The “orbit” of an electron is not the same as a satellite orbiting the earth. It is more of a “zone of probability” based on its quantum energy state, sometimes referred to as a “cloud” of probability. Because of their wavelike nature electrons do not move smoothly but tend to “jitter”. Electrons also have a precessive spin that is roughly equivalent to the earths rotation.

Adding to what @stranger_in_a_strange_land had to say, electrons move. That’s a fundamental property of them. They are always on the move. As a basic subatomic particle, they are part wave and part particle. Their wavelike property is constant motion. Electrons carry a negative electrical charge. The proton/s in the nucleus of an atom carry a corresponding positive charge. It is the atraction of those two charges that provides the Coulomb’s force that hold moving electron/s in orbit around the atomic nucleus.

ETpro (34605)

@ETpro Good summary, more readably and less “nerdy” than mine. +GA

@stranger_in_a_strange_land Thank you, kind sir, and kudos for giving me such a perfect springboard. :-)

ETpro (34605)

@ETpro – Wouldn’t it be more accurate to say electrons are both a particle and a wave depending on the observer?

Futomara (420)

@Futomara I believe it would be accurate to say they have properties of both at all times, and can be observed as either depending on the observer and circumstances.

ETpro (34605)

They’ve got noplace else to go. (Sort of the same reason that kids hang around the house all the time, and come home for meals. The ones who don’t are “free radicals”—same as the electrons.)

CyanoticWasp (20271)

Smells like teen homework.

proXXi (2906)

@Futomara Wavicles at that level, see references to De Broglie.

@proXXi Sure it is, but also good review for dinosaurs like me who haven’t thought about this stuff in 30 years.

Electrons have a finite energy. They move, because to be stationary relative to the nucleus they would need to have zero or almost zero energy. The energy they possess is expressed as kinetic energy, as well as electromagnetic potential. If they were stationary relative to the nucleus then their orbit would collapse and it would collide with the nucleus due to the electromagnetic attraction.

They aren’t really moving. If they were orbiting the nucleus like a satellite orbits the earth, they would be continuously emitting radiation according to Maxwell’s equations, and thereby losing energy until they dropped into the nucleus. This was recognized immediately upon discovery of the nuclear model of the atom and it sent physics into real tizzy.

It’s closer to the truth to consider the electrons to exist somewhere in a standing wave pattern around the nucleus. De Broglie was the first to figure this out with the hydrogen atom using the inspiration that if photons acted as both waves (according to Newton) and particles (according to Einstein in light of the photoelectric effect) then why not electrons? However, the naive interpretation of this wavelength (and the associated Schrödinger equation) as a “matter wave” did not come to pass. The modern interpretation is that what is “waving” is the probability of locating the electron at a given point in space.

I made a mistake in the previous post. Actually, Newton believed light consisted of particles. Support for the wave theory of light built over the following years and became entrenched when it was realized Maxwell’s equations described the behavior of light as well as electricity and magnetism (hence ‘electromagnetic radiation’). Einstein’s explanation of the photoelectric effect by recourse to particles went against the grain and caused a bit of controversy at the time.

Ironically, special relativity had its genesis in a conflict between Newtonian mechanics and Maxwell’s equations which Einstein came at with the firm belief that Maxwell would “win”.

Well, after our universe was born for the first 380,000 years the electrons were actually not moving around the nuclei of atoms. So another way of answering your question why the electrons do this are “lower surrounding energy levels”. The nuclei were finally able to “catch” and keep the electrons they love so dearly (using the electromagnetic force).

mattbrowne (31729)

Gravitational pull towards the neutrons and protons and magnetic repulsion from negative and positive charges.

LeopardGecko (1237)

@LeopardGecko In the context of the electromagnetic force, opposites attract. There is no magnetic repulsion between protons and electrons.

Let’s hit the mathematical interpretation straightaway.
Let’s take the case of the the Hydrogen atom which has a unit positive charged in nucleus and an electron.

Columb’s force due to attraction between the nucleus and the electron is
F=(¼pie0)q1q2/r^2
Here pi=22/7 e0=Permitivity of free speace q1 is tthe charge on nucleus and q2 = charge on electron and r is the distance between the centres of both the charges..
To Dumb it dow a bit let’s take (¼pie0)=K so We get F=Kq1q2/r^2
.
This attraction force results in the centrifugal force of the electrons that makes is revolve around the nuclear centre just like the planets revolve around the Sun due to Force of gravitation.
So we get the centripetal force on the electron is,mV^2/r
where m= mass of the electron,V is the velocity at with it spins around the nucleus and r is the distance between nucleus and the electron
.
Equating both the equations we get

Kq1q2/r^2=mV^2/r
Finally V= sqrt{(Kq1q2/rm)
As K is constant,the factors that affect the movent of electrons around the nucleus are
the charge dipole q1q1 the distance between the nucleus and the electron.
Mass of electron can be neglected in the propertionality equation as it’s always constant.To be more precise, if we neglect the constant charge of the electron we get the final propertionality equation as

V propertional to sqrt{q1/r)

Where q is the charge on the nucleus and r is the distance between the electron and nucleus.That’s why electron’s in lower orbits have higher velocity as combared to their counterparts in higher orbits or orbitals.
Hope that helps.

@proXXi I will accompany your response with this video

(double facepalm)

@Mike_Hunt Genius!!!

sndfreQ (11739)

@engineeristerminatorisWOLV, I don’t get “pie0”. Is that one that someone has already eaten, or what?

Someone’s going to step in here soon and demand that we not stray from the topic again, but until then I’m just going to say that I prefer apple or chocolate cream pies.

CyanoticWasp (20271)

@CyanoticWasp That is pi multiplied by e0, which I am assuming is the original value of e.

@engineeristerminatorisWOLV Your classical atom is unstable on account of accelerated charged particles emitting electromagnetic radiation.

Look folks, I don’t make this sh*t up…

http://en.wikipedia.org/wiki/Atom#Electron_cloud

The electrons in an atom are attracted to the protons in the nucleus by the electromagnetic force. This force binds the electrons inside an electrostatic potential well surrounding the smaller nucleus, which means that an external source of energy is needed in order for the electron to escape. The closer an electron is to the nucleus, the greater the attractive force. Hence electrons bound near the center of the potential well require more energy to escape than those at greater separations.

Electrons, like other particles, have properties of both a particle and a wave. The electron cloud is a region inside the potential well where each electron forms a type of three-dimensional standing wave—a wave form that does not move relative to the nucleus. This behavior is defined by an atomic orbital, a mathematical function that characterises the probability that an electron will appear to be at a particular location when its position is measured.[60] Only a discrete (or quantized) set of these orbitals exist around the nucleus, as other possible wave patterns will rapidly decay into a more stable form.[61] Orbitals can have one or more ring or node structures, and they differ from each other in size, shape and orientation.[62]

http://en.wikipedia.org/wiki/Bohr_model#Origin

In the early 20th century, experiments by Ernest Rutherford established that atoms consisted of a diffuse cloud of negatively charged electrons surrounding a small, dense, positively charged nucleus. Given this experimental data, Rutherford naturally considered a planetary-model atom, the Rutherford model of 1911 – electrons orbiting a solar nucleus – however, said planetary-model atom has a technical difficulty. The laws of classical mechanics (i.e. the Larmor formula), predict that the electron will release electromagnetic radiation while orbiting a nucleus. Because the electron would lose energy, it would gradually spiral inwards, collapsing into the nucleus. This atom model is disastrous, because it predicts that all atoms are unstable.

Also, as the electron spirals inward, the emission would gradually increase in frequency as the orbit got smaller and faster. This would produce a continuous smear, in frequency, of electromagnetic radiation. However, late 19th century experiments with electric discharges through various low-pressure gasses in evacuated glass tubes had shown that atoms will only emit light (that is, electromagnetic radiation) at certain discrete frequencies.

@CyanoticWasp : e0 is the permitivity of freespace.I should have used the symbols.
@hiphiphopflipflapflop : Thanks for the elaboration.

If the metal is not electrified, are the electrons of atom still revolving round the nucleus?

@Khokon_khoxx Electrons in solid metal do not strictly revolve around the nucleus. Those in lower energy levels do, but those in higher levels pass freely through the lattice in their ground state. That is why metals are such good conductors of electricity – because the flow of electrons occurs with very little resistance.