Determine the number of valence electrons in each of the following main-group elements or ions a

Determine the number of valence electrons in each of the...

Key Concepts

Valence Electrons

Valence electrons are the electrons found in the outermost electron shell of an atom and are responsible for the chemical properties and reactivity of an element. They play a critical role in how atoms bond with one another as well as in the formation of ions, because they are the electrons that can be lost, gained, or shared during chemical reactions.

Lewis Dot Structures

Lewis dot structures are diagrams that represent the valence electrons of atoms as dots around the chemical symbol of an element. These structures are used to predict molecular geometry, bonding behavior, and the possible coordination of electrons between atoms when forming chemical compounds or ions.

Main-Group Elements

Main-group elements are found in the s-block and p-block of the periodic table and typically have predictable valence electron configurations based on their group number. Their bonding and reactivity are largely determined by the number of valence electrons they possess, making them fundamental in the study of chemical bonding and molecular structure.

Ions and Electron Count

When dealing with ions, it is important to adjust the number of valence electrons according to the ion’s charge. A negative charge indicates extra electrons have been added, while a positive charge means electrons have been removed. This adjustment is essential when drawing accurate Lewis dot structures for ions, ensuring that the total count of valence electrons correctly reflects the ion’s electronic configuration.

Transcript

00:01 In this question we've been given some atoms and some ions and we've been asked to determine the valence shell electrons.

00:07 That is the valence electrons.

00:09 When we are looking at valence electrons, we are looking at the number of the electrons that are in the outermost shell.

00:17 If we look at carbon, the electronic configuration of carbon is 1s2, 2 s22p2.

00:27 So if we look at this, we have a total of two shells.

00:30 Shell 1 and shell 2 and shell 2 is the outermost shell and if we count the number of electrons we have a total of 2 plants 2 making us 4 valence electrons and if we are to draw this we are going to have something that looks like this so moving on to the next one where we are now looking at nitrogen if we look at nitrogen a simpler way would be just to look from a perspective of the periodic table remember the group number in the periodic table it gives us the number of valence electrons on an atom so if we are for example to look at nitrogen nitrogen is in group 5 so it means it has five electrons in its violent shell but not only that we are saying that because the electronic configuration of nitrogen is 1 s2 2 s2 2p 3 we have two shells here shell 1 and shell 2 and if we are to look at the valence that is the out of most shell we have these electrons three plus two electrons to give us five valence electrons so the dirt structure of nitrogen is going to be something that looks like this so remember this corresponds to the group number of nitrogen which is group five and now looking at oxygen just to simplify this oxygen is in group six so we can just conclude to say oxygen has six valence electrons and we can go on just to prove this by looking at and the electronic configuration like what we did for capone and nitrogen.

02:03 So if it has six valence electrons we're going to have something that looks like this as the lewis structure.

02:10 And then moving on to a bromide aisle.

02:13 If we look at promine, promine is in group, promine is in group 7, but now we are looking at bromide.

02:23 We have added an extra electron.

02:25 So it now has a total of eight electrons in its outermost shell.

02:31 That is in the valence shell and a bromide is something that is going to look like 1, 2, 3, 4, 5, 6, 7, 8.

02:40 This is a bromide ion.

02:43 And then finally, looking at mg, let's look at mg 2+...