What are the ion charges for the different groups?
Group Number Charge
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Define a molecule.
2 or more atoms joined together by covalent bonds.
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Define a covalent bond.
2 or more non-metals sharing electrons.
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Is the intermolecular force between molecules strong or weak?
Weak.
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When a substance melts or boils, what force/bond is overcome?
Intermolecular forces.
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Define intermolecular forces.
A weak force of attraction between molecules.
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Do substances made from simple molecules have a high or low boiling/melting point?
They have a LOW boiling point, they only have weak intermolecular forces that are easily overcome.
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Why do simple molecular substances not conduct electricity?
The molecules are neutral, they have no charge on them.
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Define an ion.
An ion that has lost or gained electrons, so they are electrically charged (positive or negative).
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Give the properties of an ionic compound.
-Giant lattice structure -Crystaline (in crystals) -High melting and boiling point -Conducts electricity when dissolved in water (aqueous), conducts electricity when molten, soluble in water.
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Define a giant lattice.
Ions are ordered in a regular structure each ion is surrounded by ions of an opposite charge.
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Fill in the missing word(s): The attraction between ions is known as _________________
Strong, electrostatic attraction.
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Why do ionic substances have high melting/boiling points?
Because the strong electrostatic attractions has to be overcome, which requires a lot of energy.
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Why do ionic substances conduct electricity when molten or aqueous?
They have free ions to move around.
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Give three examples of giant covalent substances.
Graphite, diamond and silicon dioxide.
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What are diamond and graphite both made of?
Carbon
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What are the properties of diamond?
-Each carbon atom is joined to 4 other carbon atoms. -High melting point (has lots of covalent bonds which need to be overcome) -Very hard -Does not conduct electricity.
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What are the properties of graphite?
-Each carbon atom is joined to 3 other carbon atoms by covalent bonds. -It's in layers, which can slide over each other -High melting point (because of lots of covalent bonds) -Soft - atoms can slight over each other -It conducts electricity.
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What is a delocalised electron?
An electron that is free to carry a charge.
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What are fullorines?
Fullorines are made of linked carbon rings.
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Give a use of fullorines.
Drug delivery into the body, lubricants, catalysts, and nanotubes for reinforcing.
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Give 3 properties of silicon dioxide.
-High melting point -Giant structure -Each silicon atom is joined to 4 oxygen atoms, by covalent bonds.
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Define an alloy.
A mixture of metals (often a metal mixed with carbon).
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Why are alloys stronger than pure metal?
Alloys contain different sized atoms, and this disrupts the regular atom arrangement, preventing the layers of atoms sliding over each other.
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Define a shape-memory alloy.
An alloy that returns to its original shape after being reformed. An example is nitinol (nickel and titanium) used in braces.
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Why can pure metal be bent and hammered into shape?
The regular atom arrangement means that the atoms can slide over each other easily (malleable).
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Define a polymer.
A chain of monomers joined by a polymerisation reaction.
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Define a thermosoftening polymer and state its properties.
No cross-linking between polymer chains. Properties: -When heated, they soften and melt. -Recyclable.
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Define a thermosetting reaction.
Cross-linking between polymer chains (covalent bonds). Properties: -Doesn't soften upon heating. -Non-recyclable.
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Define a nano-particle.
Between 1&100 nanometres in size (Very small).
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How do nano-particle properties differ from bulk materials?
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