Valence Electrons: Why Move from Group 1 to 17?

  • Thread starter Infrasound
  • Start date
  • Tags
    Electrons
In summary, the movement of an electron from a group 1 element to a group 17 element is due to the attraction between opposite charges. This is because the valence electron of sodium is more attracted to the nucleus of chlorine than its own nucleus. Despite the larger radius of chlorine, the effective charge that the valence electron sees is lower, making it more attractive. This is due to quantum mechanics and the existence of discrete energy levels, which results in the noble gas rule where noble gas configurations are the most stable.
  • #1
Infrasound
70
0
What causes an electron to move from a group 1 element to a group 17?

I understand that opposite charges attract, but why would the valence electron of sodium be more attracted to the nucleus of chlorine than its own?

It seems strange that this occurs if the radius of a chlorine element is so much greater than that of sodium. Doesn't electrical force decrease at a rate equal to the inverse of square of the distance from the nucleus?


Also, do we understand why electrons exist in specific energy levels? As opposed to anywhere like planetary orbits. Is this one of those quantum physics realms where I would have to understand the mathematics?

Thanks in advance for any help with either question.
 
Physics news on Phys.org
  • #2
Yeah, these are mostly due to quantum effects.

Electrons in an atom can, to a good approximation, be divided into core electrons and valence electrons. The core electrons are very tightly bound to the nucleus, and located very close to it, whereas the valence electrons are located further out. So the core electrons end up doing an effective job at screening the nuclear charge, so roughly speaking, as far as the valence electron is concerned, it will see a charge of [tex]Z - N_{\mathrm{core}}[/tex]. In sodium, it has a single valence electron and 10 core electrons, so the effective charge that the valence electron sees is just 1. A Cl atom has the same 10 core electrons, but the nuclear charge is 17, so the effective charge the valence electrons see is 7. This actually results in the Cl atom being smaller than the Na atom.

Now, you ask why do some of the electrons behave like core electrons and others behave like valence electrons, the answer is due to quantum mechanics. QM results in discrete energy levels, the highest of which are the valence which are significantly higher in energy than the core energy levels. And once you count up states, you end up with the "noble gas rule," where noble gas configurations end up being the most stable. These occur at 2,10,18,36,... total electrons, so for Na and Cl it turns out Na is more stable at Na+ with 10 electrons, and Cl is more stable at Cl- with 18 electrons. (That is, a system containing an Na+ with a Cl- is more stable than a system with a neutral Na with a neutral Cl.)
 
  • #3



I can provide some insights into the movement of valence electrons from group 1 to 17. Firstly, it is important to understand that the periodic table is organized based on the electronic configuration of elements. Elements in group 1 have one valence electron in their outermost energy level, while elements in group 17 have seven valence electrons in their outermost energy level. This means that there is a difference of one electron between these two groups.

Now, the attraction between the valence electron of sodium and the nucleus of chlorine is due to the difference in their electronegativity values. Chlorine has a higher electronegativity than sodium, which means it has a stronger pull on electrons. This is because chlorine has a higher number of protons in its nucleus, which creates a stronger positive charge, compared to sodium. So, the valence electron of sodium is more attracted to the nucleus of chlorine because of this stronger electronegativity.

Furthermore, the radius of an atom does not solely determine its electronegativity. Other factors such as the number of protons and the shielding effect of inner electrons also play a role. Therefore, even though the radius of chlorine is larger than sodium, it still has a higher electronegativity due to its other characteristics.

Regarding your question about the existence of specific energy levels for electrons, this is a fundamental concept in quantum mechanics. Electrons exist in specific energy levels because of the wave-like nature of their behavior. These energy levels are determined by the Schrödinger equation, which is a mathematical equation used to describe the behavior of particles at the atomic level. So, yes, understanding the mathematics of quantum mechanics is necessary to fully understand this concept.

I hope this helps to clarify your questions. Science is a constantly evolving field, and we are still learning and discovering more about the behavior of atoms and electrons. Keep asking questions and seeking answers, as that is the essence of scientific inquiry.
 

1. What are valence electrons?

Valence electrons are the electrons located in the outermost energy level of an atom. These are the electrons involved in chemical bonding and determining the reactivity of an element.

2. Why do valence electrons move from group 1 to 17?

Valence electrons move from group 1 to 17 in order to achieve a full outer energy level, also known as the octet rule. Elements in group 1 only have 1 valence electron, while elements in group 17 have 7 valence electrons. By transferring or sharing electrons, elements can reach a stable configuration with 8 valence electrons.

3. How do valence electrons affect an element's properties?

Valence electrons play a crucial role in determining an element's properties. Elements with a full outer energy level (8 valence electrons) are stable and non-reactive, while elements with fewer or more valence electrons are more likely to form chemical bonds in order to reach stability. This is why elements in group 1 are highly reactive, while elements in group 17 are more likely to gain electrons and form negative ions.

4. Why do valence electrons have different energy levels?

The energy levels of valence electrons vary depending on their distance from the nucleus. The further away an electron is from the nucleus, the higher its energy level. Valence electrons are located in the outermost energy level because they are shielded from the positive charge of the nucleus by the inner energy levels.

5. How do valence electrons determine an element's placement on the periodic table?

The number of valence electrons an element has determines its placement on the periodic table. Elements in the same group have the same number of valence electrons, which is why they share similar chemical properties. As you move from left to right across a period, the number of valence electrons increases by one, while the inner energy levels remain the same.

Similar threads

  • Atomic and Condensed Matter
Replies
0
Views
391
Replies
1
Views
1K
  • Atomic and Condensed Matter
Replies
5
Views
2K
  • Atomic and Condensed Matter
Replies
2
Views
2K
  • Atomic and Condensed Matter
Replies
5
Views
2K
  • High Energy, Nuclear, Particle Physics
Replies
17
Views
1K
Replies
1
Views
2K
Replies
10
Views
939
Replies
6
Views
1K
  • Atomic and Condensed Matter
Replies
1
Views
2K
Back
Top