# AS Science OCR Unit 2 Module 1

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What is pressure?
When particles collide with the walls of the container they exert a force, measured in nm^-2
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What is Boyle's Law?
When the number of molecules are squeezed into a smaller volume, the number of collisions with the walls of the container are increased, so pressure increases.
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What is Temperature Law?
When temperature increases molecules gain kinetic energy and move faster, more collisions equals great pressure, pressure directly proportional to temperature
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Bubble of air expanding
Bubble must push the surrounding atmosphere out of the way. Requires energy. So energy comes from molecules of air. Molecules lose energy and the temperature drops, so expanding air cools down
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Bubble of air contracting
Surrounding atmosphere pushes molecules closer together. Atmosphere does work, molecules gain energy so heat up
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What is the Troposphere?
The lowest layer of the earth's atmosphere. Consist of moving air masses. Up to 15 km above the surface
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What is the Stratosphere?
Layer in the earth's atmosphere between 15km and 50km from earth's surface
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What is the Tropopause?
The boundary between the Troposphere and the Stratosphere
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Air on surface heated causing expansion.Convection-hot air to rise.Hot air reaches the tropopause and spreads out horizontally. Returns to ground level by descending at tropical latitudes 30°N and 30°S. Returning air converges at the ITCZ
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Importance of ITCZ?
Position varies every year. Major factor in determining climate of tropical regions.
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How are hurricanes formed?
Condensation of water vapour that has been evaporated from our warm sea releases heat which helps to create a fast moving circulation around the centre of the hurricane.
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Factors affecting horizontal air movement?
Air moves from regions of high pressure to legions of low pressure. And Coriolis Effect
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What is Coriolis effect?
It causes moving air to be deflected (in a clockwise direction in northern hemisphere) due to the rotation of the air
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What are the features of a covalent bond?
An electron from each atom is shared to from a shared pair of electrons between 2 nuclei, nuclei repel each other due to positive charges, so negative charge of pair of electrons attracts nuclei toward each other.
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How can covalent bonds be polar?
If electrons are shared equally, then one end of a bond will be slightly negative and the other slightly positive. A bond which has opposite charges at its two ends are polar
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What is a permanent dipole?
This is when two atoms have substantially different electronegativity.
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What is electronegativity?
A measure of how strongly an atom attracts electrons in a covalent bond. The higher the electronegativity, the stronger the attraction for electrons.
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Key features of hydrogen bonding?
Very small electropositive H atom; A small electronegative atom (N, O & F); Two lone pairs of electrons.
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What are the principal features of the structure of liquid water and ice?
Unusually high melting point (273K) and boiling point (373K); an usually high specific heat capacity (4.2JK g ); density of ice is less than the density of liquid water at same temperature.
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What is specific heat capacity?
The amount of energy required to raise the temperature of 1g (1cm^3) of water by 1K.
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What is a surface current influenced by?
Prevailing winds; Coriolis effect; presence of landmass.
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What is tree ring analysis?
The amount of growth shown each year by a ring. The thickness of doing shows how favourable conditions were.
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What is pollen analysis?
Pollen grains are often preserved in peat bogs. They can be dated fairly accurately. Analysis of pollen will give information about the type of vegetation present at that time, which in turn will show what the climate was like.
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What is the hockey stick graph?
Shows for the past thousand years the average temperature is stable but in the last 50 years a dramatic increase shown by sharp curve on the graph
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What is Ice Core sampling?
Ice columns containing pockets of ancient ice are measured, to show different concentrations of gases. Help to see the concentration of gases that were abundant in each layer.
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## Other cards in this set

### Card 2

#### Front

What is Boyle's Law?

#### Back

When the number of molecules are squeezed into a smaller volume, the number of collisions with the walls of the container are increased, so pressure increases.

### Card 3

#### Front

What is Temperature Law?

### Card 4

#### Front

Bubble of air expanding

### Card 5

#### Front

Bubble of air contracting