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Elements are categorized according to their properties. Scientists found that most elements had some common properties when they researched them. Therefore, they categorized elements into two types: metals and non-metals. Today, we have three elements: metals, non-metals, and metalloids. Metalloid combines metals and non-metals, but let's not focus on it now. For the GCSE syllabus, you must learn about metals and non-metals in the periodic table. The question is, what are metals and non-metals, and how do we differentiate between them?
What are Metals?
What are Ions?
To understand what metals and non-metals are, you should know about ions. If you don't know about ions, we have a separate resource; you can go through it by clicking here. An ion is a charged particle that is made by an element. When an element loses or gains electrons, the balance of force of attraction between protons and electrons breaks. This results in one force being more significant than another force, and that causes the element to turn into a charged particle, in this case, an ion. Elements gain or lose electrons according to their shell requirement.
What are Metals?
If an element loses an electron or electrons, it will become a positive ion, and positive ions are metals. The critical point is that elements that lose an electron/electrons in a chemical reaction are metals. For example, magnesium, the chemical formula of magnesium is "Mg". The electronic configuration of magnesium is 2, 8, 2. There are two electrons in the last shell. Therefore, magnesium will try to transfer those two electrons in a chemical reaction. This will result in magnesium getting a +2 charge because it donated a pair of electrons in a chemical reaction, making it a positive ion. Since positive ions are metals, magnesium is also a metal.
This method is applied to all elements in the periodic table. If elements donate at least one electron, they are a metal. Most of the elements in the periodic table are metals.
Properties of Metals
If you move top to bottom in a group, the metallic properties of elements increase. Metals have different properties, and that makes them different from non-metals. Properties can be distinguished into two types: physical properties and chemical properties.
Physical Properties of Metals
Physical property is a characteristic of any material that doesn't involve chemical composition. Physical properties include colour, boiling points, density, hardness, etc. For metals, we will judge all the below physical properties.
- Electrical conductivity
- Heat conductivity
- Density
- Material property
- Melting and boiling points
Metals are good conductors of heat and electricity. In the case of electricity, metals have extra electrons in their valance shell that allow them to conduct electricity. In the case of heat, metals are usually solids and crystalline structures that allow them to transfer heat from one point to another.
Furthermore, metals have high density because they are usually solids in nature. In addition, metals are also shiny, malleable, and ductile. Metals also have high melting and boiling points because of the metallic bonding inside of them. This type of bonding is solid, and to overcome such force of attraction, a high amount of energy is required, which is why metals have high melting and boiling points. For example, the melting point of lithium, which is a metal, is 180°C.
Chemical Properties
Although mentioned above, it is still one of the metal's chemical properties that it will permanently lose electrons to form a positive ion. For example, magnesium reacts with chlorine to form magnesium chloride; magnesium loses two electrons to form the Mg2+ ion. Let's do a final example: lithium burns in the air to form lithium oxide. Lithium loses an electron to form Li+. When a metal reacts with any other chemical, it forms a compound. In the above examples, lithium oxide and magnesium chloride are compounds. When metal makes a compound with oxygen, most of them are essential.
What are Non-Metals?
Not every time elements donate electrons; they accept electrons—for example, fluorine. Fluorine has 9 electrons, and its electronic configuration is 2, 7. Fluorine needs an electron to fill its valance shell. When fluorine accepts an electron, a chemical reaction becomes negatively charged because electrons are in excess, and the balance between protons and electrons breaks. Hence, fluorine becomes a negative ion. If any element becomes a negative ion in a reaction, it is non-metal. Yes, fluorine is a non-metal.
The critical point to note is that non-metals will always accept electrons.
Properties of Non-Metals
As you move from left to right, the metallic properties of the elements decrease. This means that the non-metallic property increases as you move from left to right.
Like metals, non-metals also have physical properties. Due to these properties, scientists could distinguish elements from metals and non-metals.
Physical Properties of Non-Metals
Non-metals will judge the same physical properties. Non-metals are poor electric and heat conductors. They don't have excess electrons; non-metals are electron-deficient. Due to this, they can't conduct electricity. Furthermore, most of the non-metals have amorphous structures. This structure is terrible for conducting heat. Hence, they are lousy heat conductors, too.
Non-metals' density is low because they are usually in gases and liquids. In addition, non-metals are also dull and brittle. Non-metals have covalent bonding, and this type of bonding is a weak bond. Therefore, less energy is required to overcome the force of attraction, concluding that non-metals have low melting and boiling points.
Chemical Properties of Non-Metals
One of the core chemical properties of non-metals is that they form a negative ion by gaining extra electrons. For example, oxygen will always accept a pair of electrons in a chemical reaction to fill its valance shell. Suppose oxygen reacts with magnesium to form magnesium oxide. Oxygen will gain two electrons from magnesium to form O-2. Another example is chlorine. Chlorine reacts with sodium to form sodium chloride. In this reaction, the chlorine will obtain a single electron from sodium to form Cl-.
Non-metals react with oxygen to form an oxide compound. Non-metal oxides are usually acidic.
Conclusion
When elements gain electrons or electrons, they become negative charge ions and negatively charged ions are called non-metals. If elements donate electrons or electrons, they become positive charge ions and positively charged ions are called metals.
Metals are good conductors of heat and electricity and have high melting and boiling points. On the other hand, non-metals are bad conductors of heat and electricity and have low melting and boiling points. The densities of metals are usually high, but densities of non-metals are usually low. Finally, metals are shiny, ductile, and malleable, but non-metals are dull and brittle.
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Lithium is used in place of Fluorine
Hi Madan. You’re right to point that out – thanks very much for your comment!
amazing side
It’s very educative,I learnt alot thanks ❤️
Was very educative and help. Gave me a broader understanding of the topic