Graphite is one of the crystalline forms of carbon. Two of the distinctive properties of graphite are: It conducts electricity even though it is a non-metal, and It can act as a lubricant even though it has a giant covalent structure. Give a brief explanation of these properties in light of the structure of graphite. Graphite as an electrical conductor.

Graphite is a good conductor of electricity because a carbon atom has four Valence Electrons and each carbon atom is joined to any three other carbon atoms by covalent bonds. Thus, only the three valence electrons of each carbon atom in graphite are used in the bond formation. The fourth valence electron of the carbon atom is free to move. Due to the presence of free electrons in a graphite crystal, it conducts electricity.

Graphite is one of the crystalline forms of carbon. Two of the distinctive properties of graphite are: It conducts electricity even though it is a non-metal, and It can act as a lubricant even though it has a giant covalent structure. Give a brief explanation of these properties in light of the structure of graphite. Graphite are as lubricant.

Each carbon atom in a graphite layer is joined to three other carbon atoms by strong covalent bonds to form flat hexagonal rings. The various layers of carbon atoms in graphite are quite far apart so that no covalent bonds can exist between them. The various layers of carbon atoms in graphite are held together by weak van der Waals forces. Since the various layer of carbon atoms in graphite are joined by weak forces, they can slide over one another it is the softness of the graphite which make it useful as a lubricant.

The diagram below shows a representation of the structure of an ionic oxide. What is the ratio of K + ions to O 2- ions? _____ .

The ratio of K + ions to O 2- ions is 2 : 1 . When potassium combines with oxygen, it forms potassium oxide(K 2 O). Metal oxides are crystalline solids that contain a metal cation and an oxide anion. They typically react with water to form bases or with acids to form salts.

The diagram below shows a representation of the structure of an ionic oxide. What is the formula of this compound?

The formula of the compound is K 2 O .It is a base. This pale yellow solid, the simplest oxide of potassium, is a rarely encountered, highly reactive compound. It is deliquescent and will absorb water from the atmosphere, initiating this vigorous reaction.

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Upper Secondary-IGCSE

IMPORTANT

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Astatine is very rarely seen.What would your predict to be its physical state and colour at room temperature and pressure?

Important Questions on Elements and Compounds

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Upper Secondary-IGCSE

IMPORTANT

Cambridge IGCSE Chemistry Workbook 4th Edition>Chapter 3 - Elements and Compounds>Exercise 3.3>Q e

What is the trend observed in the melting point of the halogens as you go down the group?

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Upper Secondary-IGCSE

IMPORTANT

Cambridge IGCSE Chemistry Workbook 4th Edition>Chapter 3 - Elements and Compounds>Exercise 3.4>Q a

Many covalent compounds exist as simple molecules where the atoms are joined together with single or double bonds. A covalent bond, make up of a shared pair of electrons, is often represented by a short straight line.
Complete the table by filling in the spaces.
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Upper Secondary-IGCSE

IMPORTANT

Cambridge IGCSE Chemistry Workbook 4th Edition>Chapter 3 - Elements and Compounds>Exercise 3.4>Q c

Graphite is one of the crystalline forms of carbon. Two of the distinctive properties of graphite are:

It conducts electricity even though it is a non-metal, and
It can act as a lubricant even though it has a giant covalent structure.
Give a brief explanation of these properties in light of the structure of graphite.

Graphite as an electrical conductor.

HARD

Upper Secondary-IGCSE

IMPORTANT

Cambridge IGCSE Chemistry Workbook 4th Edition>Chapter 3 - Elements and Compounds>Exercise 3.4>Q c

Graphite is one of the crystalline forms of carbon. Two of the distinctive properties of graphite are:

It conducts electricity even though it is a non-metal, and
It can act as a lubricant even though it has a giant covalent structure.
Give a brief explanation of these properties in light of the structure of graphite.

Graphite are as lubricant.

HARD

Upper Secondary-IGCSE

IMPORTANT

Cambridge IGCSE Chemistry Workbook 4th Edition>Chapter 3 - Elements and Compounds>Exercise 3.5>Q c

The diagram below shows a representation of the structure of an ionic oxide.
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What is the ratio of K⁺ ions to O^2-ions? _____ .

HARD

Upper Secondary-IGCSE

IMPORTANT

Cambridge IGCSE Chemistry Workbook 4th Edition>Chapter 3 - Elements and Compounds>Exercise 3.5>Q c

The diagram below shows a representation of the structure of an ionic oxide.
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What is the formula of this compound?

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Upper Secondary-IGCSE

IMPORTANT

Cambridge IGCSE Chemistry Workbook 4th Edition>Chapter 3 - Elements and Compounds>Exercise 3.5>Q d

The following diagram shows the structure of common salt.
Extend the structure to the right, by adding four more ions.
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Upper Secondary-IGCSE

IMPORTANT

Cambridge IGCSE Chemistry Workbook 4th Edition>Chapter 3 - Elements and Compounds>Exercise 3.5>Q d

Complete the diagrams below for the ions in the structure to show their electron arrangement. Draw in any missing electron shells, showing clearly the origin of the electrons involved.
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Astatine is very rarely seen.What would your predict to be its physical state and colour at room temperature and pressure?

Important Questions on Elements and Compounds

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