Number Of Electrons In Lithium

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Learning Objectives

  1. Number Of Unpaired Electrons In Lithium
  2. Number Of Electrons In Lithium 7
  3. Number Of Electrons In Lithium-7
  4. Number Of Electrons In Lithium Ion
  • Define valence electron.
  • Be able to indicate valence electrons when given the electron configuration for an atom.

The arrangement of electrons in a lithium atom: Lithium (Li) has an atomic number of 3, meaning that in a neutral atom, the number of electrons will be 3.The energy levels are shown as concentric circles around the central nucleus, and the electrons are placed from the inside out. The number of valence electrons can be determined by looking at the location of the element in the periodic table. Lithium, for example, belongs to. Lithium is the third element with a total of 3 electrons. In writing the electron configuration for lithium the first two electrons will go in the 1s orbital. Since 1s can only hold two electrons the remaining electron for Li goes in the 2s orbital. Electron configuration is the arrangement of electrons on the orbitals. The lithium atom has a total of 3 electrons, so we have to put 3 electrons in orbitals. The first two electrons will go in the 1s orbital as S orbital can hold a maximum of two electrons only. The remaining one will go in 2s orbital.

What makes a particular element very reactive and another element non-reactive?

Number Of Unpaired Electrons In Lithium

A chemical reaction involves either electron removal, electron addition, or electron sharing. The path a specific element will take depends on where the electrons are in the atom and how many there are.

Electron Configurations of Second-Period Elements
Element Name Symbol Atomic Number Electron Configuration
LithiumLi31s22s1
BerylliumBe41s22s2
BoronB51s22s22p1
CarbonC61s22s22p2
NitrogenN71s22s22p3
OxygenO81s22s22p4
FluorineF91s22s22p5
NeonNe101s22s22p6

In the study of chemical reactivity, we will find that the electrons in the outermost principal energy level are very important and so they are given a special name. Valence electrons are the electrons in the highest occupied principal energy level of an atom. In the second period elements listed above, the two electrons in the 1 s sublevel are called inner-shell electrons and are not involved directly in the element’s reactivity or in the formation of compounds. Lithium has a single electron in the second principal energy level and so we say that lithium has one valence electron. Beryllium has two valence electrons. How many valence electrons does boron have? You must recognize that the second principal energy level consists of both the 2 s and the 2 p sublevels and so the answer is three. In fact, the number of valence electrons goes up by one for each step across a period until the last element is reached. Neon, with its configuration ending in s2p6, has eight valence electrons.

Summary

Number
  • Valence electrons are the outer-shell electrons of an atom.
  • Valence electrons determine the reactivity of an atom.

Practice

Use the link below to answer questions about valence electrons:

LithiumUnpaired

Review

Number Of Electrons In Lithium 7

  1. Define valence electron.
  2. Define inner shell electron.
  3. How many valence electrons are there in fluorine?
  4. What are the 2s electrons in nitrogen?
  5. How many inner shell electrons are there in beryllium?

Number Of Electrons In Lithium-7

Glossary

Lithium valence electrons

Number Of Electrons In Lithium Ion

  • inner-shell electrons: Those electrons that are not in the outer shell and are not involved in the reactivity of the element.
  • valence electrons: The electrons in the highest occupied principal energy level of an atom.
Show References

References

  1. User:Chemicalinterest/Wikipedia. http://commons.wikimedia.org/wiki/File:Cobalt_carbonate.JPG.