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Describe metallic bonding
Metallic bonding is when there is a lattice of positvely charged ions surrounded by delocalised electrons
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What holds a metallic bond together?
The electrostatic attractions (the attraction between the postive ions and the delocalised electrons)
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Describe covalent bonding
Covalent bonding is the common attraction between two postive nuclei and the pair of shared electrons
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Describe ionic bonding
Ionic bonding is the force of attraction bewtween oppositely charged ions
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Covalent, ionic and metallic are ______ bonds?
strong
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When do polar covalent bonds arise?
When the difference in electronegativity values is not so great as to lead to typically ionic bonds
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In the polar covalent bonds are the electrons shared equally?
No
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A molecule is described as polar if it has a _____ dipole?
permanent
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In polar molecules, are the polar bonds arranged symmetrically in the molecule?
NO
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Give an example of a polar molecule
Water (H2O)
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Give an example of a non-polar molecule that contains polar bonds
Carbon dioxide (CO2)
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What are van der waal's forces?
Van der waal's forces are intermolecular forces of attraction
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What kind of dipoles are found in molecules that have van der waal's forces?
Temporary dipoles
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The strength of van der waal's forces ______ with increasing molecular mass?
increases
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Are van der waal's forces stronger or weaker than covalent bonds?
Weaker
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Describe hydrogen bonding
Hydrogen bonds are electrostatic forces of attraction between molcules containing highly polar bonds
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Which kind of elements form these hydrogen bonds?
- Hydrogen and either:
- Nitrogen
- Oxygen
- Fluorine
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Put these bonds in order going from weakest to strongest: ionic, polar-covalent, van der waal's, hydrogen
van der waal's, hydrogen, polar-covalent, ionic
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Of the first twenty elements in the periodic table, which have a metallic lattice structure?
- Lithium (Li)
- Sodium (Na)
- Potassium (K)
- Beryllium (Be)
- Magnesium (Mg)
- Calcium (Ca)
- Aluminium (Al)
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Of the first twenty elements in the periodic table, which have a covalent network structure?
- Hydrogen (H)
- Nitrogen (N)
- Oxygen (O)
- Fluorine (F)
- Phosphorus (P)
- Sulphur (S)
- Chlorine (Cl)
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Of the first twenty elements in the periodic table, which are covlanent network gases and which are covalent network solids?
- Gases:
- Hydrogen (H)
- Nitrogen (N)
- Oxygen (O)
- Fluorine (F)
- Chlorine (Cl)
- Solids:
- Phosphorus (P)
- Sulphur (S)
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Of the first twenty elements in the periodic table, which have a covalent network structure?
- Boron (B)
- Silicon (Si)
- Carbon (C)
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Of the first twenty elements in the periodic table, which have a monatomic?
- Helium (He)
- Neon (Ne)
- Argon (Ar)
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In diamond, each carbon atom is covalently bonded to ____ other carbon atoms?
four
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In graphite each atom is covalently bonded to _____ other carbon atoms?
three
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Why is carbon in the form of graphite a conductor of electricity?
As each carbon atom is only covalently bonded to three other carbon atoms, meaning there are delocalised electrons to conduct the electricity
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In a fullerene, each carbon atom is covalently bonded to _____ other carbon atoms?
three
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Why are fullerenes not conductors of electricity?
As the delocalised electrons are contained within each discrete molecule
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Give an example of an ionic compound
- sodium chloride
- lithium chloride
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Give an example of a covalent molecular compound
- sulphur dioxide
- carbon dioxide
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Give an example of a covalent network compound
- silicon dioxide
- silicon carbide
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What is silicon carbide used for?
Cutting and grinding as it is very hard and has a similar structure to diamond
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Why do covalent substances have high melting and boiling points?
As it is strong covalent bonds that have to be broken eg silicon dioxide
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Why do covalent molecular substance have low melting and boiling points?
As it is weak van der waal's forces that have to be broken eg carbon dioxide
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Why are the boiling points of ammonia and water much higher than expected?
As they contain hydrogen bonding between molecules
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Why does water becomes less dense when it freezes?
As hydrogen bonding makes the water molecules form an open lattice with the molecules further apart than water
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The more hydrogen bonds in the molecules the ____ viscous the substance will be?
more
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Polar covalent bonds and ionic crystals dissolve in...?
polar water molecules
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Non-polar substances dissolves in...?
non-polar substances such as carbon tetrachloride
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