Video Transcript
Aluminum is in group 13. How many valence electrons are there in the valence shell of an aluminum atom?
Let’s take a look at aluminum. An aluminum atom has 13 protons represented by the atomic number on the periodic table. In a neutrally charged aluminum atom, the number of protons will be the same as the number of electrons. We can represent the arrangement of the 13 electrons by using the Bohr model of the atom. In this model, the center represents the nucleus. The first circle around the center is electron shell one, the second circle is electron shell two, and so on. The first electron shell can hold a maximum of two electrons, while the second and third electron shells can hold up to eight electrons.
Let’s draw the Bohr model for aluminum. We need to place 13 electrons in this model. We will represent an electron with a dot. We’ll start with the first electron shell. This shell can only hold two electrons, so we’ll draw two dots. The second shell can hold up to eight electrons. We have placed two of aluminum’s 13 electrons and have 11 more to place. This means that we can fill shell two. There are now a total of 10 electrons in this diagram. We can place the remaining three in the third shell. This is the completed Bohr model of the aluminum atom.
The question was asking us about the valence electrons in the valence shell of an aluminum atom. The valence shell is the outermost electron shell in an atom. For an atom of aluminum, the valence shell is shell three. The valence electrons are the outermost electrons, the electrons found in the valence shell. For an atom of aluminum, there are three valence electrons. We have determined that an atom of aluminum has three valence electrons. We solve this problem by drawing a Bohr model of the aluminum atom. But we could have used aluminum’s position on the periodic table as a shortcut.
Aluminum is found in group 13 of the periodic table. Elements of the same group are found in the same column. There are 18 columns on the periodic table. Therefore, there are 18 groups. Elements of a group share similar chemical and electronic properties. This is because elements of the same group have the same number of valence electrons. We can quickly determine the number of valence electrons for several of the groups by numbering the columns skipping the d-block elements. This tells us that aluminum, like all group 13 elements, has three valence electrons.
