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.

Draw dot and cross structural diagram to represent the bonding in the following simple molecular compounds. In the dot and cross diagram, show only the outer shells of the atoms involved. Molecule Dot and Cross diagram Structure Ammonia NH 3 Water H 2 O Hydrogen chloride HCl Ethane C 2 H 6 Ethene C 2 H 4 Ethanol C 2 H 5 OH Ethanoic acid CH 3 COOH

When a molecule is formed from the covalent bond, such compounds are known as covalent compounds. These compounds share one or more pairs of valence electrons. The covalent compound is a result of two non-metals reacting with each other such that they are electrically neutral. They exhibit characteristic physical properties that include lower melting points and electrical conductivity compared to ionic compounds.

HARD

Upper Secondary-IGCSE

IMPORTANT

Earn 100

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.

Important Questions on Elements and Compounds

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?

HARD

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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HARD

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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HARD

Upper Secondary-IGCSE

IMPORTANT

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

Draw an ionic diagram similar to the one above for the structure of magnesium chloride.

HARD

Upper Secondary-IGCSE

IMPORTANT

Cambridge IGCSE Chemistry Workbook 4th Edition>Chapter 3 - Elements and Compounds>Exercise 3.6>Q 1

Draw dot and cross structural diagram to represent the bonding in the following simple molecular compounds. In the dot and cross diagram, show only the outer shells of the atoms involved.

Molecule	Dot and Cross diagram	Structure
Ammonia $({NH}_{3})$
Water $(H_{2} O)$
Hydrogen chloride $(HCl)$
Ethane $(C_{2} H_{6})$
Ethene $(C_{2} H_{4})$
Ethanol $(C_{2} H_{5} OH)$
Ethanoic acid $({CH}_{3} COOH)$

MEDIUM

Upper Secondary-IGCSE

IMPORTANT

Cambridge IGCSE Chemistry Workbook 4th Edition>Chapter 3 - Elements and Compounds>Exercise 3.7>Q 1

The boxes below contain properties of ionic compounds and their explanations.Draw lines to link each pair.

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Important Questions on Elements and Compounds

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