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Questions and Answers
What occurs when a metal and a non-metal bond?
What is the charge of a positively charged ion?
What type of bond is formed between oppositely charged ions?
What is the shape of the crystal structure in ionic compounds?
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What is the name of the negatively charged ion in the compound Lithium Flouride?
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What is the term for the attractive force between oppositely charged ions?
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Which diagram is used to represent ionic bonds?
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What is the characteristic of ionic compounds that allows them to conduct electricity?
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What is the term for the bond formed when two non-metal atoms share a pair of electrons?
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What is the term for the electrons that are shared in a covalent bond?
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What is the reason behind the extreme stability of noble gases?
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What is the Octet Rule?
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What is the valency of an element?
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Which element has a valency of 4?
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What is the characteristic of transition metals that allows them to have variable valencies?
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Study Notes
Nobel Gases and Octet Rule
- Nobel gases are extremely stable due to their electronic configuration, which includes 8 electrons in their outer energy level.
- The Octet Rule states that when bonding occurs, atoms tend to reach an electronic arrangement with eight electrons in their outermost energy level.
- Exceptions to the Octet Rule include:
- Elements close to helium, which tend to lose electrons to have 2 electrons in their outermost energy level.
- Transition elements (d-block metals), which do not obey the Octet Rule and can have more or less than 8 electrons in their outer energy level.
- Sulphur and phosphorous, which sometimes follow the Octet Rule, but not always.
Valency
- Valency is the number of bonds an atom of an element forms when it reacts.
- Valency can be found by identifying the number of electrons an atom must lose, gain, or share to get a stable electronic configuration (i.e., Nobel Gas configuration).
- Examples of valency:
- Sodium (Na) forms 1 bond.
- Oxygen (O) forms 2 bonds.
- Carbon (C) forms 4 bonds.
Variable Valencies
- Some transition metals have variable valencies, meaning they can lose, gain, or share different numbers of electrons when they bond.
- Examples of variable valencies:
- Chromium (Cr) can have valencies of 2, 3, or 6.
- Manganese (Mn) can have valencies of 2, 3, 4, 6, or 7.
- Iron (Fe) can have valencies of 2, 3, or 6.
- Copper (Cu) can have valencies of 1 or 2.
Ionic Bonding
- Ionic bonds are created by the transfer of electrons.
- Examples of ionic bonds:
- Lithium fluoride (LiF): Lithium loses an electron to become positively charged, and fluorine gains an electron to become negatively charged.
- Ionic bonds are formed between the electrostatic attraction between oppositely charged ions.
- Cations are positively charged ions, and anions are negatively charged ions.
Predicting Ionic Compounds
- Ionic compounds are formed between ions, and the charge on ions can be used to predict the compounds they form.
- Examples of predicting ionic compounds:
- Sodium carbonate (Na₂CO₃)
- Calcium hydroxide (Ca(OH)â‚‚)
- Hydrogen sulfate (Hâ‚‚SOâ‚„)
Crystalline Structure of Ionic Compounds
- Ionic bonding does not result in the formation of molecules, but instead forms crystal structures in the shape of a lattice.
- Examples of crystalline structures:
- Sodium chloride (NaCl)
- Calcium fluoride (CaFâ‚‚)
Covalent Bonding
- Covalent bonding involves the sharing of electrons between atoms.
- A covalent bond is formed when two non-metal atoms share a pair of electrons to attain the Nobel Gas Configuration.
- Examples of covalent bonds:
- Hydrogen molecule (Hâ‚‚)
- Hydrogen chloride (HCl)
Characteristics of Ionic Compounds
- High melting and boiling points
- Solids at room temperature
- Conduct electricity
- Soluble in water
Nobel Gases and Octet Rule
- Nobel gases are extremely stable due to their electronic configuration, which includes 8 electrons in their outer energy level.
- The Octet Rule states that when bonding occurs, atoms tend to reach an electronic arrangement with eight electrons in their outermost energy level.
- Exceptions to the Octet Rule include:
- Elements close to helium, which tend to lose electrons to have 2 electrons in their outermost energy level.
- Transition elements (d-block metals), which do not obey the Octet Rule and can have more or less than 8 electrons in their outer energy level.
- Sulphur and phosphorous, which sometimes follow the Octet Rule, but not always.
Valency
- Valency is the number of bonds an atom of an element forms when it reacts.
- Valency can be found by identifying the number of electrons an atom must lose, gain, or share to get a stable electronic configuration (i.e., Nobel Gas configuration).
- Examples of valency:
- Sodium (Na) forms 1 bond.
- Oxygen (O) forms 2 bonds.
- Carbon (C) forms 4 bonds.
Variable Valencies
- Some transition metals have variable valencies, meaning they can lose, gain, or share different numbers of electrons when they bond.
- Examples of variable valencies:
- Chromium (Cr) can have valencies of 2, 3, or 6.
- Manganese (Mn) can have valencies of 2, 3, 4, 6, or 7.
- Iron (Fe) can have valencies of 2, 3, or 6.
- Copper (Cu) can have valencies of 1 or 2.
Ionic Bonding
- Ionic bonds are created by the transfer of electrons.
- Examples of ionic bonds:
- Lithium fluoride (LiF): Lithium loses an electron to become positively charged, and fluorine gains an electron to become negatively charged.
- Ionic bonds are formed between the electrostatic attraction between oppositely charged ions.
- Cations are positively charged ions, and anions are negatively charged ions.
Predicting Ionic Compounds
- Ionic compounds are formed between ions, and the charge on ions can be used to predict the compounds they form.
- Examples of predicting ionic compounds:
- Sodium carbonate (Na₂CO₃)
- Calcium hydroxide (Ca(OH)â‚‚)
- Hydrogen sulfate (Hâ‚‚SOâ‚„)
Crystalline Structure of Ionic Compounds
- Ionic bonding does not result in the formation of molecules, but instead forms crystal structures in the shape of a lattice.
- Examples of crystalline structures:
- Sodium chloride (NaCl)
- Calcium fluoride (CaFâ‚‚)
Covalent Bonding
- Covalent bonding involves the sharing of electrons between atoms.
- A covalent bond is formed when two non-metal atoms share a pair of electrons to attain the Nobel Gas Configuration.
- Examples of covalent bonds:
- Hydrogen molecule (Hâ‚‚)
- Hydrogen chloride (HCl)
Characteristics of Ionic Compounds
- High melting and boiling points
- Solids at room temperature
- Conduct electricity
- Soluble in water
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Description
Learn about the stability of noble gases and the Octet Rule in chemistry, including exceptions and special cases for certain elements.
