Year 7 Chemistry: Understanding Metals And Non-metals Basics

Detailed Explanation of Metals and Non-metals ⚛️

When learning about metals and non-metals in Year 7 Chemistry, it’s important to understand their physical and chemical properties, differences, uses, and how to identify each group. This topic is a key part of the UK National Curriculum and helps us understand the materials around us.

Physical Properties of Metals and Non-metals ✨

Metals usually have these physical properties:

• They are shiny and have a metallic lustre.
• They conduct heat and electricity well.
• Most metals are solid at room temperature (except mercury, which is liquid).
• They are malleable (can be hammered into sheets) and ductile (can be drawn into wires).
• Metals are generally dense and have high melting and boiling points.

Non-metals, on the other hand, have different physical properties:

• They are usually dull and not shiny.
• Non-metals are poor conductors of heat and electricity (insulators).
• They can be solids, liquids, or gases at room temperature. For example, sulfur is a solid, bromine is a liquid, and oxygen is a gas.
• Non-metals are brittle if solid and break easily when hammered.
• They tend to have lower densities and lower melting and boiling points compared to metals.

Chemical Properties of Metals and Non-metals ⚗️

Chemically, metals and non-metals react differently:

Metals:

• They tend to lose electrons in reactions to form positive ions (cations).
• Metals react with oxygen to form metal oxides, which are usually basic (alkaline). For example, sodium reacts with oxygen to form sodium oxide.
• Metals often react with acids to produce hydrogen gas.

Non-metals:

• Non-metals tend to gain or share electrons in reactions and usually form negative ions (anions) or covalent compounds.
• Non-metal oxides are often acidic, like sulfur dioxide forming sulfurous acid in water.
• Non-metals generally do not react with acids like metals do.

Differences Between Metals and Non-metals ⚔️

Uses of Metals and Non-metals 🏗️

Metals are used in everyday life for:

• Building materials (iron and steel in construction).
• Electrical wiring (copper and aluminium).
• Making coins (nickel and copper).
• Cooking utensils (aluminium and stainless steel).

Non-metals are used for:

• Making medicines and chemicals (carbon in drugs and plastics).
• Insulating materials (sulphur in rubber).
• Breathing (oxygen gas).
• Fertilisers (nitrogen in ammonia).

How to Identify Metals and Non-metals 🔍

You can identify metals and non-metals by observing their physical properties:

• Check if the material is shiny or dull.
• Test if it conducts electricity (using a simple circuit).
• Try bending it gently to see if it is malleable or brittle.
• Look at its state at room temperature.

Also, reaction tests can help:

• Metals fizz with acid and release hydrogen gas.
• Metals form basic oxides, non-metals form acidic oxides.

By understanding these properties and differences, you can recognise metals and non-metals and know how they are used in the world around us. Keep practising by observing everyday objects and materials, and soon it will become much easier to tell metals and non-metals apart! 🔄

10 Examination-style 1-Mark Questions on Metals and Non-metals ❓

1. What is the metal used in electrical wiring because it is a good conductor?
   Answer: Copper
2. Name the non-metal that is a gas essential for respiration.
   Answer: Oxygen
3. Which metal is known for being the lightest?
   Answer: Lithium
4. What is the non-metal used in pencils?
   Answer: Carbon
5. Name the metal that is liquid at room temperature.
   Answer: Mercury
6. Which non-metal is found in diamonds and graphite?
   Answer: Carbon
7. What is the metal commonly used to make coins?
   Answer: Copper
8. Name the non-metal that is found in water (H₂O).
   Answer: Oxygen
9. Which metal is magnetic?
   Answer: Iron
10. What non-metal is used in the production of fertilizers and explosives?
    Answer: Nitrogen

10 Examination-style 2-Mark Questions on Metals and Non-metals 📝

1. Question: State two physical properties of metals.
   Answer: Metals are usually shiny and good conductors of heat and electricity.
2. Question: Name two non-metals that are gases at room temperature.
   Answer: Oxygen and nitrogen are examples of non-metals that are gases at room temperature.
3. Question: Why do metals have high melting points?
   Answer: Metals have high melting points because their atoms are held together by strong metallic bonds.
4. Question: Give two uses of metals based on their properties.
   Answer: Metals are used in electrical wiring due to their conductivity and in cooking utensils because they conduct heat well.
5. Question: What is the usual state of non-metals at room temperature?
   Answer: Non-metals can be solids, liquids, or gases at room temperature, but many are gases or brittle solids.
6. Question: Explain why metals are malleable.
   Answer: Metals are malleable because their atoms can slide over each other without breaking the metallic bond.
7. Question: State one chemical property of non-metals.
   Answer: Non-metals often gain electrons in chemical reactions to form negative ions.
8. Question: What happens to metals when they react with oxygen?
   Answer: Metals react with oxygen to form metal oxides.
9. Question: How do non-metals generally conduct electricity?
   Answer: Non-metals usually do not conduct electricity because they lack free electrons.
10. Question: Why are some metals used for making jewellery?
    Answer: Some metals like gold and silver are used in jewellery because they are shiny and do not corrode easily.

10 Examination-style 4-Mark Questions on Metals and Non-metals 🧪

1. Question: Explain three physical properties that distinguish metals from non-metals.
   Answer: Metals are generally shiny and have a metallic lustre, while non-metals are usually dull. Metals are good conductors of heat and electricity, but non-metals are poor conductors. Most metals are malleable, meaning they can be hammered into sheets, whereas non-metals are brittle and break easily when bent.
2. Question: Describe how metals react with oxygen and give two examples of the products formed.
   Answer: Metals react with oxygen to form metal oxides. For example, when iron reacts with oxygen, it forms iron oxide, commonly known as rust. When magnesium burns in air, it forms magnesium oxide. These metal oxides are usually solid and can be basic in nature.
3. Question: Compare the boiling points of metals and non-metals and explain why there is a difference.
   Answer: Metals generally have higher boiling points compared to non-metals. This is because metals have strong metallic bonds which require a lot of energy to break. Non-metals usually have weaker intermolecular forces, such as van der Waals forces, so their boiling points are lower.
4. Question: Explain why metals are good conductors of electricity.
   Answer: Metals are good conductors because they have free electrons that can move easily through the metal structure. These free electrons carry electrical charge from one part to another, allowing electric current to flow. Non-metals lack these free electrons, so they do not conduct electricity well.
5. Question: Outline the chemical test you can do to identify a metal versus a non-metal.
   Answer: One chemical test involves reacting the substance with hydrochloric acid. Metals usually react with acid to produce hydrogen gas, which can be seen as bubbles. Non-metals generally do not react with acids in this way. This test helps to distinguish between metals and non-metals.
6. Question: Describe how the reactivity of metals changes as you go down Group 1 in the periodic table.
   Answer: As you go down Group 1, metals become more reactive. This is because the outer electron is further from the nucleus and is more easily lost during reactions. Elements like sodium and potassium react more vigorously with water than lithium does.
7. Question: Explain what happens when a metal reacts with a non-metal to form an ionic compound.
   Answer: When a metal reacts with a non-metal, the metal loses electrons to become a positively charged ion. The non-metal gains these electrons to become a negatively charged ion. The opposite charges attract, forming an ionic bond and making an ionic compound.
8. Question: Describe three uses of metals based on their physical properties.
   Answer: Metals like copper are used for electrical wiring because they conduct electricity well. Aluminium is lightweight and resistant to corrosion, making it useful for aircraft parts. Iron is strong and used in construction, such as in bridges and buildings.
9. Question: Discuss why non-metals are often found in gases or liquids at room temperature.
   Answer: Non-metals tend to have weak intermolecular forces, so their particles are not held tightly together. This means they are often gases, like oxygen and nitrogen, or liquids, like bromine, at room temperature. Metals have stronger bonds, so they are solid mostly.
10. Question: Explain the difference in malleability between metals and non-metals using atomic structure.
    Answer: Metals have atoms arranged in layers that can slide over each other when force is applied, making metals malleable. In non-metals, atoms are held by strong covalent bonds in fixed positions, so when force is applied, the structure breaks instead of bending. This is why non-metals are brittle.

10 Examination-style 6-Mark Questions on Metals and Non-metals 🧠

Question 1:

Explain how the physical properties of metals differ from those of non-metals. Include at least three differences in your answer.

Answer:
Metals and non-metals have different physical properties due to their atomic structures. Firstly, metals are generally good conductors of heat and electricity because they have free electrons that can move easily. Non-metals usually do not conduct electricity and heat well. Secondly, metals are malleable and ductile, meaning they can be hammered into sheets or drawn into wires without breaking; non-metals tend to be brittle and break easily when bent. Thirdly, metals have high melting and boiling points because their atoms are held together by strong metallic bonds. Non-metals typically have lower melting and boiling points. Additionally, metals have a shiny, lustrous appearance, whereas non-metals are usually dull. Metals also tend to be denser and heavier than non-metals. These differences arise from how atoms are arranged and bonded in metals and non-metals.

Question 2:

Describe the reactions of metals with oxygen and explain how these reactions demonstrate the chemical properties of metals.

Answer:
When metals react with oxygen, they usually form metal oxides. This reaction is an example of oxidation where the metal loses electrons to oxygen. For example, when magnesium burns in oxygen, it forms magnesium oxide, which is a white powder. This shows that metals tend to lose electrons in chemical reactions, so they act as reducing agents. The metal oxides formed are usually basic and can react with acids to produce salt and water. Different metals react with oxygen at different rates; some metals like magnesium react very quickly and produce bright flames, whereas others like iron rust slowly. These reactions demonstrate that metals are reactive because they tend to give away electrons and form compounds with oxygen. The ability to react with oxygen is a characteristic chemical property of metals.

Question 3:

Explain why metals conduct electricity, but most non-metals do not.

Answer:
Metals conduct electricity because of their structure and bonding. In metals, atoms are arranged in a regular pattern and share a ‘sea’ of free electrons that are not attached to any one atom. These free electrons can move easily through the metal, allowing electric current to flow. This is why metals are good conductors. On the other hand, non-metals have atoms that are bonded differently, usually with covalent bonds where electrons are shared between specific atoms. Non-metals do not have free electrons; their electrons are held tightly in bonds, so electric current cannot flow easily through them. Some non-metals can conduct electricity if they are in certain forms, like graphite, but most are poor conductors. This fundamental difference in how electrons behave in metals and non-metals explains their contrasting electrical conductivity.

Question 4:

Compare the reactivity of metals and non-metals with water. Use examples to support your answer.

Answer:
Metals and non-metals react differently with water depending on their reactivity. Some metals, especially alkali metals like sodium and potassium, react very vigorously with water, producing hydrogen gas and metal hydroxides. For example, sodium reacts with water to form sodium hydroxide and hydrogen gas. Other metals like iron react slowly, often rusting when exposed to water and air. Many metals such as copper and gold do not react with water at all. Non-metals typically do not react with water in the same way. Most non-metals are either unreactive with water or react only under special conditions. For example, chlorine gas can react with water to make an acid, but this is different from the reactions metals undergo. Overall, metals are generally more reactive with water than non-metals, but the exact reaction depends on the metal’s position in the reactivity series.

Question 5:

Describe the extraction of metals from their ores and explain why some metals are easier to extract than others.

Answer:
Metals are extracted from ores, which are rocks containing metal compounds. The method of extraction depends on the metal’s reactivity. Less reactive metals, such as copper, can be extracted by heating their ores in air or by heating with carbon, which reduces the ore to metal. More reactive metals, like aluminium, require electrolysis, where an electric current is passed through a molten ore solution to separate the metal. The reason some metals are easier to extract is due to their chemical reactivity. Less reactive metals do not combine as strongly with oxygen or other elements and are easier to separate from their ores. Highly reactive metals form very stable compounds and need more energy or complex methods to extract, such as electrolysis. The choice of extraction method depends on the metal’s position in the reactivity series.

Question 6:

Explain the uses of metals and non-metals in everyday life and how their properties make them suitable for these uses.

Answer:
Metals are used in many everyday items because of their properties like strength, conductivity, and durability. For example, copper is used in electrical wiring because it conducts electricity well and is malleable. Iron and steel are used for construction because they are strong and hard. Aluminium is used in airplanes and packaging because it is light and resistant to corrosion. Non-metals are used too – for example, oxygen is essential for breathing and supports combustion, and sulfur is used in making fertilizers and matches. Non-metals like carbon are present in fuels and diamonds because of their hardness. Plastics, made mostly from carbon and hydrogen, are flexible and useful for many household items. The different physical and chemical properties of metals and non-metals explain why they have varied and important uses.

Question 7:

Describe what happens when a metal reacts with an acid. Use a specific example in your explanation.

Answer:
When a metal reacts with an acid, it usually produces a salt and hydrogen gas. For example, when zinc reacts with dilute hydrochloric acid, zinc chloride and hydrogen gas are formed. The reaction happens because the metal atoms lose electrons and form positive metal ions, which combine with negative ions from the acid to make a salt. The hydrogen ions from the acid gain electrons and form hydrogen gas, which bubbles off. This is a displacement reaction where the metal displaces hydrogen from the acid. Not all metals react with acids; metals lower in the reactivity series, like copper, do not react with dilute acids. This reaction shows that metals can act as reducing agents and helps identify the reactivity of different metals.

Question 8:

Explain the differences in bonding between metals and non-metals and how this affects their melting and boiling points.

Answer:
Metals have metallic bonding, where positively charged metal ions are surrounded by a ‘sea’ of free electrons. This strong bonding needs a lot of energy to break, so metals usually have high melting and boiling points. The free electrons also allow metals to conduct heat and electricity. Non-metals have covalent bonds where atoms share electrons in pairs. Some non-metals exist as small molecules with weak forces between the molecules, so they have low melting and boiling points, like oxygen or nitrogen. Others, like diamond, have very strong covalent networks and very high melting points. The type of bonding affects how strongly the atoms are held together, which in turn affects the melting and boiling points of metals and non-metals.

Question 9:

Describe how the properties of metals make them suitable for electrical wiring, and explain why non-metals are generally not used for this purpose.

Answer:
Metals are suitable for electrical wiring because they are excellent conductors of electricity. This is due to the free electrons in their metallic bonding, which allow electric current to flow easily. Metals like copper and aluminium are commonly used because they have high conductivity, are ductile (can be drawn into thin wires), and are strong enough to withstand handling and installation. They also resist corrosion to some extent, which improves their durability. Non-metals generally do not conduct electricity because their electrons are tightly bound in covalent bonds and cannot move freely. This makes non-metals poor conductors, so they are not suitable for wiring. Some forms of carbon, like graphite, can conduct electricity, but they are not flexible or strong enough for wiring purposes.

Question 10:

Explain what is meant by the term ‘reactivity series’ of metals and describe how it helps in predicting the products of metal displacement reactions.

Answer:
The reactivity series is a list of metals arranged in order of their reactivity from most reactive to least reactive. It helps us predict how metals will react with water, acids, and other metal compounds. In displacement reactions, a more reactive metal can displace a less reactive metal from its compound. For example, zinc can displace copper from copper sulfate solution because zinc is higher in the reactivity series. The reactivity series also shows why some metals like gold do not react easily, as they are at the bottom. By knowing the reactivity series, chemists can predict which metals will react with acids, water, or other metal salts and what products will form during these chemical reactions. This is very useful in industry and laboratory work.