OCR GATEWAY GCSE PHYSICS P1

P1

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What was Dalton's model?

-very small indestructible sphere

-atoms in element are all the same

-atoms in one element are different from others in other elements

What was Thomson's model?

-discovered negative electrons

-overall atoms are neutral with no electrical charge

-plum pudding model of atom

-atoms consist of positive mass

What is the Rutherford model?

-discovered some materials emit alpha particles that have + charge

-tiny postively charged nucleus with electrons orbiting outside

-most mass of atom is in nucleus

What is the Bohr model?

-electrons can only move in fixed orbits called electron shells or they would just spiral into the nucleus

Describe the atom

Positively charged nucleus surrounded by negatively charged electrons with the nuclear radius much smaller than that of the atom with almost all of the mass in the nucleus

How are big are atoms and molecules (order of magnitude) ?

10 to the power of -10

Define density?

-how much mass in a certain volume

- property of a material and not of the actual object

Explain the differences in density between the different states of matter in terms of the arrangements of the atoms and molecules

In 1cm 3 of a substance in the solid state there are many more particles than if it was a gas. The mass of the solid would be much higher too which relates to the density

IT depends on mass of particles also

How is mass conserved when substances change state?

-particles do not appear or disappear

-you have to add or remove material for the mass to change

What is the difference between energy and temperature?

-energy(J) depends on particle arrangement and how fast they are moving/vibrating

-temp tells u abt the avergae kinetic energy of particles

Describe how heating a system will change the energy stored within the system and raise its temperature or produce changes of state

Heat energy is transferred to kinetic energy which the particles begin to gain and vibrate more and more, INCREASING the energy and temperature

When the particles have gained enough energy, they will break the attractive forces between them and change state

What is a physical and chemical reaction?

-physical: do not make new substances bc particles are simply rearranged so its easily reversible

MATERIAL RECOVERS ITS ORIGINAL PROPERTIES

-chemical: joining atoms together in different ways

-cannot easily reverse

What is specific heat capacity?

-energy needed to raise the temp of 1Kg of a material by 1K

-heating increases internal energy

-tells u how resistant a material is to change in temp

-depends on type of material, mass, temperature rise

What is specific latent heat?

-energy transferred when 1Kg of substance changes

-FUSION= solid to liquid vice versa

-VAPORISATION= liquid to gas vice versa

How is SLC different to SHC?

-latent heat is abt change of state

-heat capacity is abt change of temp

Explain how the motion of molecules in a gas is related to both to its temp and pressire

P: faster motion, higher pressure means more collisions in a container that cannot expand

T: higher temp, faster motion as particles gain more energy

How are pressure and volume related?

-inversely proportional

bc u half volume, double number of collisions between particles n container

How does doing work (applying force) on a gas affect the temp? (bicycle pump)

- by applying force on a gas, energy has been transferred to the particles

- temperature has increased bc kinetic energy has been increased also

What is a simple model of the Earth's atmosphere?

-a single layer of gas that protects the earth

-density is the same in all parts

What is atmospheric pressure and why does it vary with height above the surface of the planet?

AP= pressure that the gases of the atmosphere exert

higher you are (say on the top of a mountain) = as you go away from the ground (surface of the earth) = AP decreases = less air above pushing down

Explain the bag of chips in a plane

the bag of chips are made at a normal pressure and level on the surface on the earth so the AP is high and equal to the pressure of the interior of the packet.

when brought somewhere that is away from the surface of the ground, AP decreases while the pressure in the packet stays the same bc its air tight

so now there is difference in pressure. the pressure outside is less than the interior causing the chips to inflate

vice versa when the chips decrease, the pressure outside is higher than inside

Explain why pressure in a liquid varies with depth and denisty

DEPTH= the molecules in any layer in a liquid are being compressed by the weight of all the liquid above that layer. This pushes the water molecules

DENSITY= in the denser liquid there is a greater weight of liquid pushing down

Explain upthurst

ON ANY OBJECT THAT FLOATS there is an upwards force that balances its weight

Describe the factors which influence floating and sinking

depends on density of object in comparison to density of fluid it is being placed in

if object is heavier per vol (larger density/heavier in mass), than fluid youre placing it in, it will sink.

SUBMARINES need to sink and float. therefore, they compress air to increase density (increasing mass of air by squeezing it into a smaller volume) to sink. to float they release the air into a larger volume so the mass of air decreases and the submarine floats towards the surface of the water