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Questions and Answers
What are valence electrons?
What are valence electrons?
Valence electrons are the number of electrons in an atom's outer shell.
What is valency?
What is valency?
Valency is the number of electrons an atom needs to gain or lose to become stable.
For groups I to IV, the valency is the same as the ______ no.
For groups I to IV, the valency is the same as the ______ no.
group
Match the following groups with their respective valency:
Match the following groups with their respective valency:
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What is the formula for Magnesium Chloride?
What is the formula for Magnesium Chloride?
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What comes first in a metal and a non-metal compound?
What comes first in a metal and a non-metal compound?
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Which of the following compounds contains hydrogen?
Which of the following compounds contains hydrogen?
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What is the chemical formula for Sodium Hydroxide?
What is the chemical formula for Sodium Hydroxide?
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What is the chemical formula for Magnesium Nitrate?
What is the chemical formula for Magnesium Nitrate?
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What is the chemical formula for Calcium Sulfate?
What is the chemical formula for Calcium Sulfate?
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What is the chemical formula for Sodium Carbonate?
What is the chemical formula for Sodium Carbonate?
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In an ionic compound, the number of positive charges is equal to the number of negative charges.
In an ionic compound, the number of positive charges is equal to the number of negative charges.
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Study Notes
Valence Electrons and Valency
- Valence electrons are the electrons in the outer shell of an atom, crucial for bonding.
- Valency indicates how many electrons an atom must gain or lose to achieve stability.
Determining Valency
- For groups I to IV, valency equals the group number and the number of valence electrons.
- For groups V to 0, the valency is calculated as 8 minus the group number.
- Valencies correspond as follows:
- Group 1: +1
- Group 2: +2
- Group 3: +3
- Group 4: -4
- Group 5: -3
- Group 6: -2
- Group 7: -1
- Group 0: 0
Magnesium Chloride Example
- Magnesium (Mg) is in Group II, with a valency of 2; Chlorine (Cl) is in Group VII, with a valency of 1.
- The formula writing involves:
- Symbols: Mg Cl
- Valencies: Mg2 Cl1
- Swapping: Mg1 Cl2
- Simplifying gives the final formula: MgCl2.
Compound Naming Rules
- For compounds with a metal and a non-metal, the metal's symbol precedes the non-metal, which ends with -ide.
- In hydrogen-containing compounds, hydrogen is listed first.
- When two non-metals are involved, the one from the lower group number comes first. If both are in the same group, the lower one is listed.
Common Compound Formulas
- Sodium Hydroxide: NaOH
- Magnesium Nitrate: Mg(NO3)2
- Calcium Sulfate: CaSO4
- Sodium Carbonate: Na2CO3
Ionic Compounds and Charge Balance
- In ionic compounds, the total positive charges balance the total negative charges.
- Charge information is derived from the valences of the elements involved.
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Description
This quiz focuses on key concepts from Chapter 4 of the IGCSE Chemistry curriculum. It includes important terminology related to valence electrons and valency, providing a solid foundation for understanding chemical bonding. Use these flashcards to test your knowledge and prepare effectively for your chemistry exams.
