Chemistry Unit 2

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Why do electron pairs repel eachother?
Because all electrons are negatively charged.
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What are allotropes?
Different forms of the same element in the same state.
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What are the three allotropes of carbon?
Diamond, graphite and fullerines.
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What is nanotechnology?
Making materials and devices from nano particles.
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If nanoparticles in sunscreen reflect UV radiation, why do they appear transparent?
Because they are so small.
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What is electronegativity?
The ability to attract bonding electrons in a covalent bond.
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How do differences in electronegativty cause bond polarisation?
Bonding electrons are pulled towards the most electronegative atom. The bond is polar. The causes a dipole to form from a difference in charge between the atoms.. The greater the difference in electronegativity, the more polar the bond.
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What are two types of intermolecular forces?
Permanent dipole- dipole interactions and hydrogen bonding.
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What are permanent dipole- dipole forces?
Dipoles on polar molecules that cause weak electrostatic forces of attraction between molecules.
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What is hydrogen bonding?
When an electronegative atoms draws electrons away from a hydrogen atom. Because hydrogen has a high charge density, a weak bond between hydrogen and lone pair of the electronegative atom is formed.
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When does hydrogen bonding occur?
When hydrogen is covalently bonded to fluorine, nitrogen or oxygen.
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What is the strongest intermolecular force?
Hydrogen bonding.
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Why can alcohols dissolve in water?
Because the polar O-H bond in alcohols attracts the polar O-H bond in water.
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Why don't halogenoalkanes dissolve in water?
Because dipoles of the polar bonds aren't strong enough to form hydrogen bonds.
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What are redox reactions?
The transfer of electrons, when oxidation and reduction occur simultaneously.
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How do group 2 elements react with water?
They produce a metal hydroxide and hydrogen.
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Why do group 2 elements become more reactive with water as you move down the group?
Because the ionisation energies decrease.
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How do group 2 elements react with oxygen?
They produce solid white oxides - different flame colours.
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How to group 2 elements react with chlorine?
They produce solid white chlorides.
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What is thermal decomposition?
When a substance breaks down when its heated.
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Why do flame colours occur?
Electron transition happens. Energy is released in the form of light when electrons return to lower energy levels. The difference of these levels determines the wavelength. Different wavelengths appear in different colours.
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What is electron transition?
When energy absorbed from a flame causes electrons to move to higher energy levels.
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Other cards in this set

Card 2

Front

What are allotropes?

Back

Different forms of the same element in the same state.

Card 3

Front

What are the three allotropes of carbon?

Back

Preview of the front of card 3

Card 4

Front

What is nanotechnology?

Back

Preview of the front of card 4

Card 5

Front

If nanoparticles in sunscreen reflect UV radiation, why do they appear transparent?

Back

Preview of the front of card 5
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