Log In Start studying!

Select your language

Suggested languages for you:

Select your language

Suggested languages for you:
StudySmarter - The all-in-one study app.
4.8 • +11k Ratings
More than 3 Million Downloads
Free
|
|

Lattice Structures

Lattice Structures

What does ionic, covalent, and Metallic Bonding all have in common? The fact that they can all form lattice structures. Because each lattice has a structure and bonding of different types, this causes them to have different physical properties, such as differences in solubility, melting point, and conductivity, which can all be explained by their varying chemical structures.

  • Firstly, we will look at the definition of the lattice structure.
  • After that, we shall explore the types of lattice structures: ionic, covalent, and metallic.
  • Then, we will look at the characteristics of different lattices.
  • We will have a look at some examples of lattices within these sections.

Define Lattice Structure

If you zoom in on any material down to the atomic scale, you will find that the atoms are arranged in an orderly fashion. Imagine the carcass of a building. This arrangement of atoms is generally a repition of a basic arrangement of atoms. This "unit" which can make the entire structure of the material if repeated enough number of times is called the lattice structure of the material.

A lattice is a three-dimensional arrangement of ions or atoms in a crystal.

Types of lattice structures

Atoms or ions in a lattice can be arranged in multiple ways in 3D geometry.

Face-centred cubic (FCC) lattice structure

This is a cubic lattice, with an atom or ion at each of the 4 corners of the cube, plus an atom at the centre of each of the 6 faces of the cube. Hence, the name face-centred cubic lattice structure.

Body-centred cubic lattice structure

As you can deduce by the name, this lattice is a cubic lattice with an atom or ion at the centre of the cube. All the corners have an atom or ion, but not the faces.

Lattice structures BCC lattice structure StudySmarter Body centered cubic lattice[1], Golart, CC BY-SA 3.0, via Wikimedia Commons

Hexagonal closest packed lattice structure

Now, the name of this lattice structure might not be painting a picture in your head right away. This lattice is not cubic like the previous two. The lattice can be divided in three layers, with the top and bottom layers having atoms arranged in a hexagonal manner. The middle layer has 3 atoms which are sandwiched between the two layers, with tthe atoms snugly fit in the gaps of the atoms in the two layers.

Imagine arranging 7 apples like the top or bottom layer of this lattice. Now try stacking 3 apples on top of these apples - how would you do it? You would put them in the gaps, which is precisely how the atoms in this lattice are arranged.

Examples Of Lattice Structures

Now that we know the arrangement that the atoms of a compound can exist in, let us look at some examples of these lattice structures.

Giant Ionic Lattice

You may remember from our articles on Bonding that Ionic Bonding occurs via the transfer of electrons from metals to non-metals. This causes metals to become charged by losing electrons, forming positively charged ions (cations). Non-metals, on the other hand, become negatively charged by gaining electrons. Ionic bonding, therefore, involves strong electrostatic forces forming between oppositely charged ions in a lattice structure.

These compounds can be arranged in giant ionic lattices called ionic crystals. They are referred to as “giant” as they are made up of large numbers of the same ions arranged in a repeating pattern.

An example of a giant ionic lattice is sodium chloride, NaCl. In the lattice of sodium chloride, the Na+ ions and Cl- ions are all attracted to each other in opposite directions. The ions are packed together in a cubic shape with the negative ions being larger in size than the positive ions.

Lattice Structures Diagram of a giant ionic lattice of NaCl StudySmarterDiagram of a giant ionic lattice of NaCl. StudySmarter Originals

Another example of a giant ionic lattice is Magnesium Oxide, MgO. Similar to the lattice of NaCl, Mg2+ ions and O2- ions are attracted to each other in its lattice. And also similar to the lattice of NaCl, they are packed together in a cubic lattice. Negative ions of Oxygen are larger than the positive ions of Magnesium.

Lattice Structures Lattice structure of magnesium oxide, MgO StudySmarterLattice structure of magnesium oxide, MgO | Embibe

Covalent Lattices

Another important type of bond is Covalent Bond. Covalent bonding takes place between non-metals only.

Covalent bonding is the strong electrostatic attraction between two positive nuclei and the shared pair of electrons between them.

There are two types of structures that can contain covalent bonding: giant covalent structures and simple covalent structures. The difference between them is that the electrostatic attraction holding giant structures together is stronger than the electrostatic attraction holding simple structures.

Simple Molecules

Some examples of simple molecular lattices would be iodine, buckminsterfullerene (C60), and ice.

Buckminsterfullerene (C60) is an allotrope of carbon, which means its molecules only consist of carbon atoms. There are total 60 carbon atoms in buckminsterfullerene (C60) which are arranged in 20 hexagonal rings, and 12 pentagonal rings. These rings form a spherical structure.

Lattice Structures Diagram representing buckminsterfullerene C60 StudySmarterDiagram representing buckminsterfullerene (C60). Studysmarter Originals


When water freezes, the H2O molecules arrange themselves in a crystal lattice structure. Did you know that water expands when it freezes? That is because the water molecules get more space between them when arranged in a crystal structure than in liquid state. The red circles are oxygen atoms, and the yellow circles are hydrogen atoms.


Iodine is another simple molecule with its molecules arranged in a crystal lattice. Iodine molecules arrange themselves in a face-centric-cubic lattice. A face centric cubic lattice is a cube of molecules with other molecules on the centre of the faces of the cube.

Lattice Structures Iodine unit cell diagram StudySmarterIodine unit cell, shared under public domain, Wikimedia commons

Lattice of iodine can be a little hard to visualize even with an image. Look at the lattice from above - you'll see that molecules on the right and left side of the cube are aligned in the same way, while those in the middle are aligned the other way.

Giant covalent structures

Examples of giant molecular lattices are graphite, diamond, and silicon (IV) oxide.

Lattice Structures Diagram showing the shapes of the giant molecular lattices StudySmarterShapes of the giant molecular lattices. StudySmarter Originals

Graphite is an allotrope of Carbon i.e., it is completely made up of carbon atoms. Graphite is a giant covalent structure because millions of carbon atoms can exist in a single molecule of graphite. Carbon atoms are arranged in hexagonal rings, and several rings are joined together to form a layer. Graphite consists of several of these layers stacked on top of each other.

Lattice Structures Structure of Graphite StudySmarterStructure of Graphite, shared under public domain, Wikimedia Commons.

The bonds shared by carbon atoms in a layer are strong covalent bonds. Each carbon atom makes 3 single covalent bonds with 3 other carbon atoms. There are weak intermolecular forces between layers (shown by dotted lines in the figure). Graphite is a unique material with some very interesting properties and uses, which you can read more about in an article dedicated to Graphite.


Diamond is yet another allotrope of carbon, and a giant covalent structure. Diamond and graphite both are made completely of carbon, but have completely different properties. This is because of the difference in the lattice structure of the two compounds. In diamond, carbon atoms are arranged in a tetrahedral structure. Each carbon atom makes 4 single covalent bonds with 4 other carbon atoms.

Lattice Structures Diamond Structure Diagram StudySmarterStructure of Diamond | Carbons are arranged in a tetrahedral geometry | shared under public domain, Wikimedia Commons

This tetrahedral geometry makes diamond the hardest material in the world! You can read more about Diamond in an article dedicated to it.


Another example of a giant covalent structure is silicon (IV) oxide, also known as silica. Silica is the major constituent of sand. The chemical formula of silica is SiO2. Like diamond, atoms in silica are also arranged in a tetrahedral geometry.

Lattice Structures Silicon dioxide structure StudySmarterTetrahedral geometry of Silicon dioxide | Created using images from Wikimedia commons shared under public domain

Due to the tetrahedral structure, silicon (IV) oxide is very hard. Silica is also used in the formation of glass.

Metallic Lattices

When atoms of metals are closely packed together, they create a regular shape which we call a giant metallic lattice.

Within this lattice, there are free electrons in the outer shell of the metal atoms. These free electrons are also known as ‘delocalised’ electrons and they are free to drift around the structure allowing positive ions to form. This causes Metallic Bonding to occur.

Metallic bonding is the strong electrostatic attraction between the delocalised electrons and the positive metal ions.

An example of a metallic lattice is calcium, and its ions have a 2+ charge. Copper forms a face-centred-cubic (FCC) lattice. In an FCC lattice, there is an atom at each vertex of the cube, and there is an atom at the centre of each face of the cube. Metals form giant metallic structures as they consist of millions of atoms.

Characteristics Of Lattices

Ionic Lattices

Giant ionic lattices have very high melting and boiling points because of the strong attraction holding the ions together.

They conduct electricity but only when they are dissolved or molten. When ionic lattices are in a solid state, their ions are fixed in position and cannot move so electricity is not conducted.

Giant ionic lattices are soluble in water and polar solvents; however, they are insoluble in non-polar solvents. Polar solvents have atoms that have a large difference in Electronegativity. Non-polar solvents contain atoms with a relatively small difference in electronegativity.

Covalent Lattices

Simple covalent lattices:

Simple covalent lattices have low melting and boiling points because they have weak Intermolecular Forces between the molecules. Therefore, only a small amount of energy is required to break the lattice.

They do not conduct electricity in any of the states – solid, liquid, or gas as there are no ions or delocalised electrons to move around the structure and carry a charge.

Simple covalent lattices are more soluble in non-polar solvents and are insoluble in water.

Giant covalent lattices:

Giant covalent lattices have high melting and boiling points as a large amount of energy is required to break the strong bonds between the molecules.

Most of these compounds cannot conduct electricity because there are no free electrons available to carry a charge. However, graphite can conduct electricity because it has delocalised electrons.

These types of lattices are insoluble in water as they don’t contain any ions.

Metallic Lattices

Giant metallic lattices have moderately high melting and boiling points because of the strong metallic bonding.

These lattices can conduct electricity when solid or liquid as free electrons are available in both states and can drift around the structure carrying an electric charge.

They are insoluble in water due to the metallic bonds being very strong. However, they can be soluble in only liquid metals.

Lattice Parameters

Now that we have understood different types of lattice structures and their characteristics, we will now look into lattice parameters which will describe the geometry of a unit cell of a crystal.

Lattice parameters are the physical dimensions and angles of a unit cell.

Lattice Structures Diagram showing the Lattice parameters StudySmarterA unit cell of a simple cube with lattice parameters marked | Archana Tadimeti | StudySmarter Originals

Lattice parameters for this simple cube are a,b,c and angles \( \alpha , \beta , \gamma \). All of these are collectively called as lattice parameters which are the same for some other cubic systems like FCC or BCC.

For simple cubic, FCC and BCC, the dimensions a,b, and c are equal, i.e., \(a=b=c\) and the angles between them \( \alpha = \beta = \gamma = 90^ \circ \).

Lattice Constants

"A lattice constant refers to the constant distance between unit cells in a crystal lattice."[2]

Lattice constant are unique for each crystal depending upon the structure of their unit cell. For example, the lattice constant, a of Polonium is 0.334 nm or 3.345 A° . How has this been derived?

To understand this, let us have a look at how the polonium atoms are distributed in its simple cubic lattice.

Lattice Structures Simple Cube StudySmarterSimple Cubic crystal | Cdang,Samuel Dupré,Daniele Pugliesi CC BY-SA 3.0, via Wikimedia Commons[3]

Each Po atom sits on the corners of the cube. As you know that this cube is not alone but surrounded by unit cells three dimensionally. That is why this picture depicts only the parts of the atom (assumed as spheres) that are within this particular unit cell, hence drawn as if the atoms are 'chopped off', whose remaining spare parts are with other unit cells surrounding this one.

Now, let us get back to the length of each edge of this unit cell-represented by 'a' . Each atom at the edge has a radius of 'r'. Thus, the length of the edge, \(a = r + r = 2r \).

Now that we are clear that \( a = 2r\) , we will use this to calculate the lattice constant of Polonium.

From the periodic table, the atomic radius of polonium , \(r = 0.168\space nm \) . Therefore, the lattice constant of Polonium is \( 2 \times r = 2 \times 0.168 \space nm = 0.336\space nm \) .

Now that we have understood what a lattice constant is, let us jump into a few uses of studying lattice structures.

Uses of lattice structure

The lattice structure that the atoms of a compound form affects its physical properties such as ductility and malleability. When the atoms are arranged in a face-centred cubic lattice structure, the compound exhibits a high ductility. Compounds with an hcp lattice structure exhibit the lowest deformability. Compounds with bcc lattice structure lie between those with fcc and hcp in terms of ductility and malleability.

The properties affected by lattice structures are used in many materials applications. For example, atoms in graphite are arranged in an hcp lattice. Since the atoms are arranged with an offset to the atoms in the layers above and below, the layers can shift with respect to each other relatively easily. This property of graphite is used in pencil cores - the layers can shift and detach easily and be deposited on any surface, allowing a pencil to "write".

Lattice Structures - Key takeaways

  • A lattice is a three-dimensional arrangement of ions or atoms in a crystal.
  • Giant ionic lattices are referred to as “giant” as they are made up of large numbers of the same ions arranged in a repeated pattern.
  • Ions in a giant ionic lattice are all attracted to each other in opposite directions.
  • There are two types of covalent lattices, giant covalent lattices, and simple covalent lattices.
  • The electrostatic attraction holding giant structures together is stronger than the electrostatic attraction holding simple structures.
  • Metals form giant metallic lattice structures which consist of atoms that are closely packed together in a regular shape.

References

  1. Golart, CC BY-SA 3.0(https://creativecommons.org/licenses/by-sa/3.0/) , via Wikimedia Commons
  2. https://www.sciencedirect.com/topics/engineering/lattice-constant
  3. CCC_crystal_cell_(opaque).svg: *Cubique_centre_atomes_par_maille.svg: Cdang (original idea and SVG execution), Samuel Dupré (3D modelling with SolidWorks) derivative work: Daniele Pugliesi (talk) derivative work: Daniele Pugliesi, CC BY-SA (https://creativecommons.org/licenses/by-sa/3.0/ 3.0), via Wikimedia Commons

Frequently Asked Questions about Lattice Structures

 A lattice is a three-dimensional arrangement of ions or atoms in a crystal.

Lattice structures can be used for additive manufacturing.

- Giant ionic lattices

- Covalent lattices

- Metallic lattices

An example is sodium chloride, NaCl. The ions in this structure are packed in a cubic shape. 

1. Draw a square

2. Draw an identical square offset from the first one.

3. Next, join the squares together to make a cube.

4. Then, divide the cubes into 8 smaller cubes.

5. Draw three lines through the centre of the cube,  from the centre of each face to the centre of the opposite face.

6. Add the ions, but remember the negative ions (Cl-) will be larger in size than the positive ions.

Final Lattice Structures Quiz

Question

What is a lattice? 

Show answer

Answer

A lattice is a three-dimensional arrangement of ions or atoms in a crystal.

Show question

Question

What is the definition of covalent bonding?

Show answer

Answer

Covalent bonding is the strong electrostatic attraction between two positive nuclei and the shared pair of electrons between them.

Show question

Question

What is the difference between giant covalent structures and simple covalent structures? 


Show answer

Answer

The difference is that the electrostatic attraction holding giant structures together is stronger than the electrostatic attraction holding simple structures.

Show question

Question

What is the definition of metallic bonding?

Show answer

Answer

Metallic bonding is the strong electrostatic attraction between the delocalised electrons and the positive metal ions.

Show question

Question

Do ionic lattices conduct electricity?

Show answer

Answer

They conduct electricity but only when they are dissolved or molten. When ionic lattices are in a solid state, their ions are fixed in position and so they cannot move. As a result of this, electricity is not conducted.

Show question

Question

Why do simple covalent lattices have low melting and boiling points?

Show answer

Answer

They have weak intermolecular forces between the molecules. Therefore, only a small amount of energy is required to break the lattice.  

Show question

Question

Why do giant covalent lattices have high melting and boiling points?

Show answer

Answer

A large amount of energy is required to break the strong covalent bonds between the molecules.

Show question

Question

What is the arrangement of ions in a giant ionic lattice?

Show answer

Answer

The ions are packed together in a cubic shape with the negative ions being larger in size than the positive ions. 

 

Show question

Question

Give three examples of giant molecular lattices?

Show answer

Answer

- Graphite

- Silicon (IV) oxide

- Diamond

Show question

Question

Give three examples of simple molecular lattices?

Show answer

Answer

- Iodine 

- Buckminsterfullerene (C60)

- Ice

Show question

Question

Are giant ionic lattices soluble?

Show answer

Answer

Giant ionic lattices are soluble in water and polar solvents, however, they are insoluble in non-polar solvents.

Show question

Question

Are covalent lattices soluble?


Show answer

Answer

Simple covalent lattices and giant covalent lattices are both insoluble in water. 

Show question

Question


Are metallic lattices soluble?

Show answer

Answer

Metallic lattices are insoluble in water due to the metallic bonds being very strong.

Show question

Question

Do metallic lattices conduct electricity?

Show answer

Answer

Metallic lattices can conduct electricity when solid or liquid as free electrons are available in both states and can drift around the structure carrying an electric charge. 

Show question

Question

Can covalent lattices conduct electricity?


Show answer

Answer

Covalent lattices cannot conduct electricity as there are no delocalised electrons to move around the structure and carry a charge.

Show question

Question

State three different types of lattice structures.

Show answer

Answer

Ionic lattices, covalent lattices, metallic lattices. 

Show question

Question

Give a definition of lattice structures. 

Show answer

Answer

A specific arrangement of ions, molecules, or atoms in three dimensions.

Show question

Question

What are two different physical properties of lattice structures?

Show answer

Answer

Conductivity and Melting/Boiling point

Show question

Question

Is solubility a physical or chemical property?

Show answer

Answer

Chemical 

Show question

Question

Select the correct answer

Show answer

Answer

Ionic lattices have a high melting point

Show question

Question

Which os the two compounds might have a lower melting point?

Show answer

Answer

MgO

Show question

Question

Which of the two compounds will have a boiling point higher than the rest?

Show answer

Answer

LiF

Show question

Question

Which of the following lattices is comprised of more than one element. 

Show answer

Answer

Table salt

Show question

Question

Which state is required for ionic lattices to conduct electricity?

Show answer

Answer

Molten or dissolved (aqueous)

Show question

Question

Which of the following is more likely to conduct electricity in its solid form?

Show answer

Answer

Ionic lattices

Show question

Question

What type of solvent are ionic lattices more likely to dissolve in?

Show answer

Answer

Polar

Show question

Question

What type of lattice can dissolve in liquid metal?

Show answer

Answer

Metallic lattices

Show question

Question

Can insoluble lattices be sometimes dissolved at different conditions? ie. raising the temperature?

Show answer

Answer

Yes

Show question

Question

What type of solvents will dissolve giant covalent structures sometimes?

Show answer

Answer

None.

Show question

Question

Which forces make ionic lattice melting points so high?

Show answer

Answer

Electrostatic forces (between ions)

Show question

60%

of the users don't pass the Lattice Structures quiz! Will you pass the quiz?

Start Quiz

Discover the right content for your subjects

No need to cheat if you have everything you need to succeed! Packed into one app!

Study Plan

Be perfectly prepared on time with an individual plan.

Quizzes

Test your knowledge with gamified quizzes.

Flashcards

Create and find flashcards in record time.

Notes

Create beautiful notes faster than ever before.

Study Sets

Have all your study materials in one place.

Documents

Upload unlimited documents and save them online.

Study Analytics

Identify your study strength and weaknesses.

Weekly Goals

Set individual study goals and earn points reaching them.

Smart Reminders

Stop procrastinating with our study reminders.

Rewards

Earn points, unlock badges and level up while studying.

Magic Marker

Create flashcards in notes completely automatically.

Smart Formatting

Create the most beautiful study materials using our templates.

Sign up to highlight and take notes. It’s 100% free.

Get FREE ACCESS to all of our study material, tailor-made!

Over 10 million students from across the world are already learning smarter.

Get Started for Free
Illustration