Variable valency explanation and cause

In summary, transition elements such as Fe have variable oxidation states due to the energy level of their electron configurations. This means they may not always follow the octet rule, as it is a crude approximation for main group elements. The exact cause for their variable oxidation states can be explained by computational chemistry and the energy levels of different electron configurations. Even elements like nitrogen, which are not transition elements, can show variable valency and their electronic configuration may not always follow the aufbau principle.
  • #1
adi1998
15
0
many transition elements have variable oxidation state like Fe.what is the exact cause for this?they may not obey the octet rule,but what is the reason behind this?Also,elements like nitrogen are not transition elements and still show variable valency.what will be the electronic configuration of such elements?is it always according to aufbau principle?then which electrons will take part in the reaction,like in Fe---1s1,2s2,2p6,3s2,3p6,4s2,3d7
 
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  • #2
Octet rule is obeyed mostly by 2nd row elements, and even then not always, so don't treat it as a starting point. The real force behind is the energy - the lower the energy, the more stable the configuration. Sometimes energy is particularly low for some configurations and these are the only ones we observe, but more often there are several configurations, each with their own energy minimum (not much different from others), and all are observed.
 
  • #3
octet rule is a very crude approximation for main group elements. for a quantitative reason why electron shells are what they are, you need computational chemistry.
 

FAQ: Variable valency explanation and cause

1. What is variable valency?

Variable valency is a term used in chemistry to describe the ability of certain elements to have different valence states or oxidation numbers. This means that these elements can form different types of chemical bonds with other elements, depending on the conditions and the other atoms involved.

2. What causes variable valency?

The cause of variable valency is the existence of multiple oxidation states for certain elements. This is due to the presence of different numbers of electrons in the outermost energy level, which determines the element's valence state and its ability to form bonds with other elements.

3. Which elements exhibit variable valency?

Elements in the transition metals group (groups 3-12) on the periodic table are known to exhibit variable valency. This includes elements such as iron, copper, and chromium.

4. How does variable valency affect chemical reactions?

Variable valency can greatly impact the types of chemical reactions that an element can participate in. Elements with variable valency can form different types of bonds with other elements, leading to a wider range of possible reactions and products.

5. How is variable valency determined in an element?

The valency of an element is determined by the number of electrons in its outermost energy level. For elements with variable valency, this number can vary depending on the conditions and other elements involved in a chemical reaction.

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