Americas
Europe
The Periodic Table is organized so that the columns have similar properties. These columns are called groups or families, and each have their own distinct names and properties. In this article, we will be learning all about the elements of group 3A, such as their physical and chemical properties. Keep reading…
Explore our app and discover over 50 million learning materials for free.
Lerne mit deinen Freunden und bleibe auf dem richtigen Kurs mit deinen persönlichen Lernstatistiken
Jetzt kostenlos anmeldenThe Periodic Table is organized so that the columns have similar properties. These columns are called groups or families, and each have their own distinct names and properties.
In this article, we will be learning all about the elements of group 3A, such as their physical and chemical properties. Keep reading to find out more!
Let's start by looking at the definition of group 3A elements.
Group 3A are the elements in the 13th column of the periodic table
Because they are in the 13th column, they are also called group 13. They are also called the "boron family" since they start with boron, as shown below:
Fig.1-Group 3A location on periodic table
This group is different from group 3, which is the third column of the periodic table. This is the first column of transition metals. Group 3A is the third column across when you skip the transition metals.
The group 3A elements in order are:
Boron (B): Element 5
Aluminum (Al): Element 13
Gallium (Ga): Element 31
Indium (In): Element 49
Thallium (Tl): Element 81
There is another element in this group called nihonium (Nh). It is man-made, and the small amounts of it that were made decayed in seconds. While it is calculated to have properties similar to group 3A elements, not enough is known about it to be thoroughly talked about.
Let's first talk about each element's Electron Configuration, since they will give us some insight on some of each element's properties.
Electron Configuration is the distribution of electrons around the nucleus of an atom
Below is each group 3A element's electron configuration:
| Element | Electron configuration |
| Boron (B) | 1s22s22p1 |
| Aluminum (Al) | 1s22s22p63s23p1 |
| Gallium (Ga) | 1s22s22p63s23p63d104s24p1 |
| Indium (In) | 1s22s22p63s23p63d104s24p64d105s25p1 |
| Thallium (Tl) | 1s22s22p63s23p63d104s24p64d104f145s25p65d106s26p1 |
The Valence Electrons are highlighted in blue.
Valence Electrons are the electrons in the outermost energy level/shell. They are the electrons that participate in Bonding
All 3A electrons have 3 valence electrons, which is why they are often referred to as "group 3A" instead of group 13.
There are clear trends in the physical properties of this group. However, boron is often an outlier. Boron, unlike the other 3A elements, is a metalloid, which shares properties of non-metals and metals. The other group 3A elements are metals.
Here are some common properties of group 3A elements:
Soft, silver/grey metals
Boron is brittle and is either a dark crystal or brown powder
For comparison, here is what boron and thallium look like:
Fig.2 Comparing boron to thallium
Good conductors of electricity
Boron is a good conductor at high temps, but it as an insulator (poor conductor) at room temp
Low melting/boiling points
Boron's has a significantly higher boiling point than the other group 3a elements
As you can see, since Boron is a metalloid, its properties are somewhat unlike the other group 3A elements, however, as you'll see later, it's reactivity "falls in line" with most or all of the other elements in the group.
Another way we can characterize the physical properties of a group is by looking at how these properties change for element to element. Let's look at some different properties and their trends across the group:
Boiling point
As you go down the group, boiling point decreases
-There is a sharp decrease between boron and aluminum
Atomic radius (distance between center of nucleus and outermost electron(s))Atomic radius increases as you move down the group. However, Aluminum is larger than gallium. This is because gallium has d-electrons, which do a poor job of "shielding" the attractive force of the nucleus from other electrons. Because of this, the attractive force of the nucleus is stronger, meaning the electrons will be held more closely, causing the radius to be smaller.
Think of it like putting pieces of paper in between two magnets. The paper "shields" the magnets from each other, so the attractive force is weakened. However, if there are fewer sheets of paper, the attractive force is stronger. Electronegativity (the tendency to attract/gain electrons)Electronegativity decreases as you move down the table. The order of most to least electronegative is:
boron > gallium > indium > thallium > aluminum
All the group 3A elements have a +3 oxidation state, except thallium, which has a +1 oxidation state.
Oxidation state is a hypothetical charge. It represents the number of electrons gained (-x) or donated (+x) when Bonding.
In this case, that means most 3A elements will lose 3 electrons, meaning they lose all of their valence electrons. This means that they have a new and complete "set" of valence electrons (i.e. the electrons in the energy level below the highest are now the highest energy level).
Thallium only loses one electron, so it will have a full 6s-orbital.
Because boron is a metalloid, it forms mainly covalent bonds, which are bonds where the electrons are shared between two non-metals or a non-metal + metalloid. However, the other group 3A elements usually form ionic bonds. These are bonds where one element donates electrons to another element.
The group 3A elements have a common set of compounds they produce, let's walk through some of them
Oxides
All group 3A's elements are able to react with oxygen gas (O2), as shown below:
$$G_{(s)} + O_{2\,(g)} \rightarrow G_2O_3$$
Where "G" is a group 3A element. However, thallium is the exception, since it forms TlO2 because of it's +1 oxidation state (oxygen has a -2 oxidation state).
Except for thallium, all group 3A elements react with Nitrogen gas (N2) as shown below:
$$G_{(s)} + N_{2\,(g)} \rightarrow GN$$
Where "G" is a group 3A element. Nitrogen has a -3 oxidation state, which is why the ratio is 1:1.
Halides
The last type of reaction we are going to talk about is with the halides (group 17). Like with the oxides, all the halide compounds follow a similar formula, except for thallium.
Below is a general group 3A halide reaction:
$$G_{(s)} + X_{2\,(g)} \rightarrow GX_3$$
Where "G" is a group 3A element and "X" is a halide (ex: Cl2, Br2, etc.). Halides have a -1 oxidation state, which is why the general form is GX3, but thallium forms TlX.
As a summary of what we've learned, here are the group 3A characteristics:
Metals
Except for boron, which is a metalloid
Good conductors
Boron only at high temps
Low melting/boiling points
Except for boron
Have 3 valence electrons
Have a +3 oxidation state
except for thallium, which has a +1 state
Will react with oxygen gas, nitrogen gas, and halides
Thallium will not react with nitrogen gas
Group 3A is also called group 13 or the "boron family"
Group 3A (minus thallium) has an oxidation state of +3, so they lose electrons. Thallium also loses an electron (ox.state of +1)
Group 3A is the 13th column of the periodic table. These elements were grouped together because of their similar properties
Group 3A elements have a variety of uses, for example aluminum is commonly used in cans and boron is used as a flame retardent.
Below are each group 3A element's electron configuration. The valence electrons are in bold
Boron: 1s22s22p1
Aluminum: 1s22s22p63s23p1
Gallium: 1s22s22p63s23p63d104s24p1
Indium: 1s22s22p63s23p63d104s24p64d105s25p1
Thallium: 1s22s22p63s23p63d104s24p64d104f145s25p65d106s26p1
YOUR SCORE
Your score:
Already have an account? Log in
SIGNUP SIGNUPFlashcards in Group 3A15
Start learningWhere are the group 3A elements located on the periodic table?
The 3rd column
What are the group 3A elements?
Why do we exclude nihonium when talking about group 3A?
While it is calculated to have properties similar to group 3A elements, not enough is known about it to be thoroughly talked about.
What is an electron configuration?
Electron configuration is the distribution of electrons around the nucleus of an atom
Which of the following is the general form for the electron configuration of group 3A valence electrons?
ns2np1
How many valence electrons do group 3A elements have?
3
Already have an account? Log in
How would you like to learn this content?
How would you like to learn this content?
Free chemistry cheat sheet!
Everything you need to know on . A perfect summary so you can easily remember everything.
The first learning app that truly has everything you need to ace your exams in one place
Sign up to highlight and take notes. It’s 100% free.
Save explanations to your personalised space and access them anytime, anywhere!
Sign up with Email Sign up with AppleBy signing up, you agree to the Terms and Conditions and the Privacy Policy of StudySmarter.
Already have an account? Log in
Explanations 
Exams 
Magazine 
