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# Metals and Non-metals

Metals and Non-metals

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All matter in the universe is made up of chemical elements. At the time of writing, there are 118 elements have been confirmed to exist and scientists believe there are even more that are yet to be discovered. As the periodic table contains so many elements scientists investigated how the elements were related to each other and how they should be organised. From this research, the periodic table of elements was created. Within the periodic table itself we can generally see that elements are broadly divided into two groups; metals and non-metals.

For instance, the air in the Earth's atmosphere is made out of a mixture of molecular nitrogen and oxygen, plus a trace amount of other elements. While alloys such as brass are made up of a combination of copper and zinc. The atmosphere contains an overwhelming ratio of non-metals to metals, while pure alloys contain only metal. In this article, we will be exploring the properties and characteristics of both metals and non-metals.

• Firstly, we will explore the definition of metals and non-metals.
• We will then study the characteristics of metals and non-metals by studying their differences.
• Afterwards, we will then investigate different elements and determine whether they are metals or non-metals.
• Finally, we will go through some practice questions you might see in your exams.

## Metals and non-metals definition

As previously mentioned, elements are divided into two broad categories; metals and non-metals.

Metals are elements that chemically react by losing their outer electrons to form positive ions.

Non-metals are elements which do not form positive ions when going through a chemical reaction.

A way in which we can differentiate between a metal and a non-metal is by analysing the way they behave in a chemical reaction. Elements try to achieve better stability by having a full outer shell of electrons.

In the Bohr model of the atom, the first electron shell can only hold a maximum of two electrons, while the second and third shells contain eight electrons when filled up. Inner shells must be filled up before electrons start to fill outer shells. You do not need to worry about electron shells past the third shell at this level.

They can do this in two ways:

1. by gaining electrons,
2. by losing electrons.

Elements that lose electrons in chemical reactions end up forming positive ions are metals. While the elements that do not form positive ions, instead gain electrons to form negative ions. Furthermore, elements in group 0 (which already have a full outer shell of electrons) exhibit the properties and characteristics of non-metals too.

Ions are atoms or molecules that have an electric charge due to gaining or losing electrons.

Nevertheless, there can be exceptions. Some elements have the characteristics of elements from metals and non-metals. These types of metals are called metalloids or semi-metals.

One example of this is silicon, which has an atomic structure like metal but cannot conduct electricity well.

In the periodic table, we have a general trend. As you move across the period from left to right on the periodic table the metal characteristics of elements decrease. As you go down a group, the metal characteristics of elements increase.

Recall that the period number corresponds to the number of electron shells that are at least partially filled, while the group number corresponds to the number of electrons in the outer shell. Those of you with keen observation skills will notice from the periodic table that with increasing period numbers comes an increasing number of elements classified as metals than the row before it. Why is this?

Fig. 2 - The element Bismuth as a synthesised crystal.

Let us use Bismuth $$\ce{Bi}$$ as an example. It has a group number of 5 so has 5 electrons in its outer shell. Moreover, it has a period number of 6 so has 6 electron shells in total, which is quite a lot. You might mistakenly assume that it would be easier for Bismuth to gain 3 electrons than to lose 5 electrons to achieve stability. However, the negatively-charged electrons in the sixth shell are very far away (in relative terms) from the positively-charged nucleus. This means the electrons in the sixth shell are only weakly bound to the nucleus. This actually makes it easier for Bismuth to lose 5 electrons than to gain 3!

Remember that metals are defined by their tendency to chemically react and form positive ions. As Bismuth prefers to lose electrons it will become a positive ion after a chemical reaction and therefore be classified as a metal. (The information in this deep dive only scratches the surface of why Bismuth reacts to form a positive ion, the full explanation requires knowledge of quantum physics.)

## Characteristics of metals and non-metals

Now that we know what metals and non-metals are let us explore the difference between the two. We can start by looking at their electron configurations. Metals of a low atomic number will generally have 1-3 outer shell electrons and non-metals will have 4-8 outer shell electrons.

Let's move on to bonding, metals bond through metallic bonding via the loss of the outer electrons. Non-metals use other types of bonding such as covalent bonding, where electrons are instead shared between atoms in molecules.

In terms of conductivity, metals are very good conductors of electricity but non-metals are bad conductors of electricity.

Conductivity is the ability of a substance to transfer heat energy or electrical current from one place to another.

Let's move on to how metals and non-metals react chemically with a couple of common substances. When reacting with oxygen, metals form basic oxides with some being amphoteric. Non-metals form acidic oxides which can sometimes be neutral. In addition, metals can readily react with acids, whereas non-metals tend to not react with acids.

A molecule or ion that is amphoteric has the ability to react with a base and an acid.

An acid oxide which is neutral displays none of the typical properties of acids and cannot form salts.

Looking at the physical properties of metals on metals and non-metals. Metals tend to be shiny, are solid at room temperature (apart from mercury), are malleable, ductile and have a high melting and boiling point. On the other hand, non-metals are dull and do not reflect light, their states at room temperature vary, they are brittle and have relatively low melting and boiling points.

Malleability is a measure of how easy it is to bend a material into shape.

Ductility is how easily a material can be drawn into thin wires.

Fig. 3 - A bundle of copper wire. It is malleable and ductile, therefore exhibiting the characteristics of a metal.

 Characteristic Metal Non-metal Electron configuration 1-3 outer electrons 4-7 outer electrons Conductivity Good conductor Bad conductor Bonding Forms metallic bonds by losing electrons Forms covalent bonds by sharing electrons Oxide Forms basic oxides with some being amphoteric Forms acidic oxides with some being neutral Reacting with acids Readily reacts with acids Tends to not react with acid Physical properties Shiny Not shiny Solid at room temperature (except mercury) Different states at room temperature Ductile and malleable Brittle High boiling point Low boiling point High melting point Low melting point

Table. 1 - Characteristics of metals and non-metals

## Metal and non-metal elements

So we have discussed what metals and non-metals are, and their characteristics. But which elements are metal and non-metals? Let us explore a few common examples.

### Oxygen

Oxygen is a non-metal and has the chemical symbol $$\ce{O}$$. It is one of the most common elements found on earth and the second-most abundant element in the atmosphere. Oxygen is an important element as it is required for the survival of both plants and animals. Oxygen is not found by itself, rather scientists have to separate it from other elements. Oxygen has two allotropic forms (diatomic and triatomic) that occur in nature, molecular oxygen $$\ce{O2}$$ and ozone $$\ce{O3}$$.

An element can be allotropic if it can exist in more than one physical form.

By itself, oxygen is colourless, odourless and has no taste. Oxygen has many practical applications. For example, animals and plants require oxygen to carry out respiration which produces energy. Oxygen is also used in manufacturing and fueling rocket engines.

### Carbon

Fig. 4 - A synthesised diamond, which is an allotropic form of carbon.

Carbon is also a non-metal and has the chemical symbol $$\ce{C}$$. Carbon is another element that is important for life. Virtually all molecules in all living organisms contain carbon as it can readily form bonds with many other types of atoms, which allows the flexibility and function that most biomolecules require.

Carbon is allotropic and can exist as graphite and diamonds, which are both valuable materials. Also, substances that have large amounts of carbon, like coal, are burned to provide us with energy to power our daily lives, these are known as fossil fuels.

### Aluminium

Aluminium is a metal and has the chemical symbol $$\ce{al}$$. Aluminium is one of the most abundant metals on earth. It is lightweight and its metallic properties allow it to be used in a variety of industries such as transportation, building and more. It is key to how we live our modern-day lives.

### Magnesium

Magnesium is a metal and has the chemical symbol $$\ce{Mg}$$. Magnesium is another metal that is lightweight and abundant. Like oxygen, magnesium is not found by itself. Rather, it is usually found as a part of compounds in the rocks and soil. Magnesium can also be used to separate other metals from their compounds, as it is something called a reducing agent. As it is not very strong, it is often combined with other metals to make alloys to become more useful as a construction material.

## Metals and non-metals examples

We have so far explored the definition of metals and non-metals, their different characteristics and some examples of their elements and their uses. Let us consolidate our knowledge and answer some practice questions.

Question

What is a metalloid and give an example of one.

Solution

Elements that have the characteristics of elements from metals and non-metals. An example of this is silicon, which has a structure like metal but cannot conduct electricity well.

Question 2

Give three differences between a metal and a non-metal.

Solution 2

Metals are good conductors of electricity but non-metals are bad conductors of electricity. Metals readily react with acids and non-metals do not. Finally, metals form metallic bonds, and non-metals form covalent bonds.

Question 3

An element has a group number of 2 and a period number of 2. Without consulting the periodic table, do you expect this element to be a metal or a non-metal?

Solution 3

The element has a period number of 2, which means it has a small atomic number. The element also has a group number of 2, which means it has 2 electrons in its outer shell. At a low atomic number, it is easier for this element to attain stability by losing two electrons than by gaining 6.

By losing 2 negatively-charged electrons the element becomes a positively charged ion. This element is a metal.

## Metals and Non-metals - Key takeaways

• Elements can be divided into two broad categories: metals and non-metals.
• Metals are elements that form negative ions when going through a chemical reaction.
• Non-metals are elements which do not form positive ions when going through a chemical reaction.
• Elements that have characteristics of both metals and non-metals are called metalloids.
• There are many differences between metals and non-metals such as; metals are good conductors of electricity and non-metals are not.
• An example of a metal element is aluminium.
• An example of a non-metal element is oxygen.

## References

1. Fig. 2 - Bi-Crystal (https://commons.wikimedia.org/wiki/File:Bi-crystal.jpg) by Alchemist-hp and Richard Baltz is licensed by CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0/deed.en)
2. Fig. 3 - Enamelled litz copper wire (https://commons.wikimedia.org/wiki/File:Enamelled_litz_copper_wire.JPG) by Alisdojo public domain
3. Fig. 4 - Diamond Age (https://www.flickr.com/photos/jurvetson/156830367) by Steve Jurvetson is licensed by CC BY-SA 2.0 (https://creativecommons.org/licenses/by/2.0/)

Metals are giant structures of atoms that are arranged in a regular pattern. Whereas, non-metals are elements which do not form positive ions when going through a chemical reaction.

Metals are good conductors of electricity, shiny and form metallic bonds.

Non-metals are bad conductors of electricity, dull and form covalent bonds.

Metals are on the left and non-metals are on the right.

An examples of a metal is aluminium. An example of a non-metal is oxygen.

17 metals are classified as non-metals on the periodic table.

## Metals and Non-metals Quiz - Teste dein Wissen

Question

What is the definition for the reactivity series of metals?

A list of metals ordered in terms of their reactivity.

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Question

Which of these metals is more reactive?

Potassium.

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Question

Which of these metals is more reactive?

Copper.

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Question

Which of the following does not occur in a reaction between water and group one metals?

Production of hydrogen gas.

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Question

The reactivity of the group one alkali metals decreases with an increasing period number.

False.

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Question

Which of these metals is least reactive?

Lithium.

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Question

Which of these metals is least reactive?

Gold.

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Question

Why is it sometimes considered unhelpful when metals are chemically bonded to oxygen?

Metals tend to corrode over time when exposed to oxygen.

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Question

Which of these metals is least reactive?

Copper.

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Question

Which of these metals is least reactive?

Silver.

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Question

What is the most reactive metal?

Potassium.

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Question

Which of the following is an endothermic reaction?

Potassium and water.

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Question

What is the word equation for the reaction between a metal and an acid?

Acid + Metal → Salt + Hydrogen.

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Question

What is the word equation for the reaction between a group one metal and water?

Metal + Water → Hydrogen + Metal Hydroxide.

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Question

What is the symbol equation (including state symbols) for a reaction between potassium and water?

\begin{align} &2\mathrm{K}(s) + \mathrm{H}_2\mathrm{O}(l)  \rightarrow \\ &2\mathrm{KOH}(aq) + \mathrm{H}_2(g) \end{align}.

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Question

What is the definition of a metal?

Elements which chemically react by losing their outer electrons to form positive ions.

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Question

What is the definition of a non-metal?

Elements which do not form positive ions when going through a chemical reaction.

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Question

What is a metalloid?

Elements that have the characteristics of metals and non-metals

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Question

As you move across the periodic table, does the metallic characteristics increase or decrease?

Decrease.

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Question

As you move down the periodic table, does the metallic characteristics increase or decrease?

Increase.

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Question

What is the definition of amphoteric?

The ability to react with a base and acid.

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Question

What is the electron arrangement of non-metals with low atomic numbers?

4-8 outer electrons.

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Question

When metals react with oxygen, what is formed?

Basic oxides with some being amphoteric.

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Question

When non-metals react with oxygen, what is formed?

Acidic oxides with some being neutral.

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Question

Which of these is a metal element?

Magnesium.

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Question

Which of these is a non-metal element?

Chlorine.

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