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Group 3A

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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 to find out more!

• First, we will learn what elements are in group 3A and where to find them on the periodic table.
• Next, we will learn about the group's physical properties.
• Then, we will cover their chemical properties.
• Thereafter, we will look at some common reactions/compounds of this group.
• Lastly, we will summarize the characteristics we have learned.

Group 3a Elements

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.

Group 3A Electron Configuration

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.

Physical Properties of Group 3A Elements

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.

Trends in Physical Properties' Table

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

Chemical Properties of Group 3a Elements

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.

Group 3A Reactions and Compounds

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).

Nitrogen

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.

Group 3A Characteristics

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 - Key takeaways

• Group 3A are the elements in the 13th column of the periodic table. They are also called group 13 or the "boron family".
• All group 3A elements have 3 valence electrons, which have the general electron configuration of ns2np1
• Some common properties of group 3A elements are:
• Soft, silver/grey metals
• Boron is brittle and is either a dark crystal or brown powder
• 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 is significantly higher than the other group 3a elements
• The group 3A elements have a +3 oxidation state, except for thallium, which has a +1 oxidation state
• Group 3A elements commonly react with oxygen (G2O3, TlO2), nitrogen (GN, no Tl compound), and the halides (GX3, TlX)

References

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

Group 3A Quiz - Teste dein Wissen

Question

Where are the group 3A elements located on the periodic table?

The 3rd column

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Question

What are the group 3A elements?

• Boron (B): Element 5
• Aluminum (Al): Element 13
• Gallium (Ga): Element 31
• Indium (In): Element 49
• Thallium (Tl): Element 81

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Question

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.

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Question

What is an electron configuration?

Electron configuration is the distribution of electrons around the nucleus of an atom

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Question

Which of the following is the general form for the electron configuration of group 3A valence electrons?

ns2np1

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Question

How many valence electrons do group 3A elements have?

3

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Question

True or False: All 3A elements are metals

False

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Question

True or False: All group 3A elements are good conductors at all temperatures

False

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Question

True or False: Aluminum is the least electronegative group 3A element

True

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Question

What is the general oxidation state for group 3A elements

+3

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Question

Which of the following is not a possible group 3A-oxygen compound?

Tl2O3

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Question

True or False: All group 3A elements react with nitrogen gas

False

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Question

Why does thallium tend to react differently than the other group 3A elements?

It has a different oxidation state

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Question

Boron tends to form ___ bonds, while the other group 3A elements for ___ bonds

Covalent, ionic

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Question

Which of the following best describes most of the group 3A elements?

Soft, silvery metals

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