Particle model of matter Flashcards
An atom has a small, …………… charged nucleus surrounded by orbiting ……………. charged electrons.
- positively
- negatively
what is the avg radius of atoms?
1 × 10 to the -10 metres
what fraction of an atom does the nucleus make up?
The radius of a nucleus is less than 1/10 0000 of the radius of an atom
where is most of the mass of the atom concentrated at?
the nucleus
In what environment would the relative mass of an atom change?
mass is constant across all enviroments
what is the overall charge of an atom?
neutral (0)
what is the relative charge of a proton?
+1
where are protons found?
the nucleus
what is the correlation between atomic number and number of protons?
an elements atomic number is the number of protons it possesses
((all atoms of the same element have the same number of protons)
what is the relative charge of electrons?
-1
where are electrons found in the atom?
on fixed orbits (energy levels/shells/orbitals) around the nucleus
why do atoms overall have no electric charge?
because the total number of negative electrons equals the number of positive protons
what is the relative charge of neutrons?
0 -meaning that they are neutral
where are neutrons found in the atom?
in the nucleus
What is the overall charge of the nucleus of an atom?
positive
What is the charge of an atom’s nucleus?
positive
An atom’s ………….. are arranged at different distances from the nucleus (different energy levels). .
electrons
Where is most of the mass of an atom found?
the nucleus
how was the nucleus discovered?
Ernest Rutherford discovered the nucleus by firing a beam of alpha particles at thin metal foils (only a few atoms wide).
What did Rutherford’s experiment tell us?
- The large deflections suggested that some positively charged mass is the atom was repelling the particles
- suggested that most of the atom is made up of empty space
how did Rutherford’s experiment adapt the model of the atom?
-this lead to the model of the atom with negatively charged electrons orbiting a positively charged nucleus
During Rutherford’s experiment what were fired at the metal?
alpha particles
Why would the alpha particles be deflected by a smaller angle if the thin metal foil was made of a lighter element?
The nuclei of lighter elements contain fewer protons. This means they have a lower charge. Each alpha particle will therefore experience a smaller electric force acting on it and so deflect by a smaller angle.
who discovered electrons and in what year?
- English physicist J. J. Thompson
- 1897
who discovered that alpha particles could bounce off atoms thus concluding that an atom’s mass is concentrated in an atoms nucleus and in what year?
- Ernest Rutherford
- 1909
what did Neils Bohr discover
that electrons orbit the nucleus at fixed dstances
who discovered that some particles in the nucleus have no charge at all (Neutrons) and in what year?
- James Chadwick
- 1932
How did J. J. Thompson model the atom as? -and what is it?
as a ‘Plum Pudding’
- a ball of positive charge (Dough) with negatively charged electrons (Currents) mixed in with the ‘dough’
in order of discovery what are the three models of the atom over time?
1897 - Plum Pudding Model
1909 - Nuclear Model
1932 - The Modern Model
what type of foil did Rutherford use?
Thin gold foil
what happens when atoms absorb electromagnetic radiation?
Electrons move to a higher energy level further away from the nucleus
what happens when atoms emit electromagnetic radiation?
Electrons can drop to a lower energy level, closer to the nucleus
What can be emitted by atoms to change the electron arrangement in an atom?
Radiation
Each electron shell has a different ………. level. When an atom absorbs or emits ………………….. radiation, its electron arrangements can change.
- energy
- electromagnetic
what is the electron configuration of Calcium? (it has 20 electrons)
2,8,8,2
what is the electron configuration of Argon? (it has 18 electrons)
2,8,8
what is the electron configuration of Phosphorous? (it has 15 electrons)
2,8,5
who are the 4 important people in the history of the atom model?
- Ernest Rutherford
- J. J. Thompson
- James Chadwick
- Neils Bohr
what is the equation for density?
p = m/V density = mass / volume
what is upthrust?
the force that keeps an object afloat
what does the law of diplacement state?
that if an object completely submerged in liquid (like water) will replace an amount of fluid equal to its own volume
what allows an object to float on a liquid?
the object will float if its density is lower then that of the liquid E.g. A rubber duck on water
what is density measured in?
kilograms per meter cubed
Ice has a lower density than water. This means that it should float in water. Steel has a density significantly higher than water. However, a steel ship still floats. Suggest how this is possible.
The steel hull of a ship contains a large volume of air. This means that the average density of a ship is lower than the average density of water. This allows steel ships to float.
what is the least dense state of matter?
Gas
liquids are …………. dense then solids but …………. dense then gases
- less
- more
what is the most dense state of matter?
Solid
How many states of matter are there? (Disregarding plasma)
3
what are the 3 states of matter?
- solid
- liquid
- gas
what happens to the mass wen a substance changes state?
it is conserved and stays the same
how are changes of state not the same as chemical reactions?
because the material recovers (Gets back) to its old properties f the change is reversed
what is the reversible and physical process in which mass is conserved?
the change of state
what are the 4 changes of state?
- Boiling
- Melting
- Solidifying/Freezing
- Condensing
what is boiling?
turning a liquid into gas
what is melting?
turning a solid into a liquid
what is solidifying/freezing?
turning a liquid into a solid
what is condensing?
turning a gas into a liquid
When does a liquid boil?
when the particles have enough energy to completely escape the forces between them
a solid melts when…
- solid particles can overcome the forces between them
- its at its melting temperature
If mass is 10 kg and volume is 2.5 metres cubed, what is the density of the object?
4 Kg/m cubed
what is the melting and freezing point equivalence?
melting point = freezing point
The law of displacement says that an object completely submerged in a fluid (like water) will replace an amount of fluid equal to its own ……………
volume
what is an objects internal energy?
the sum (total) of the kinetic and chemical energy of the particles in the object
where does the chemical (Internal) energy on an object come from?
from potential energy stored in the bonds between particles
where does the kinetic (Internal) energy of an object come from?
the random notion of the particles
how does increasing temperature of a body (object) affect kinetic energy?
increases the kinetic energy of the body’s particles, increases the body’s internal energy
the temperature of a body is a measure of …………….. energy of its particles
-kinetic
what are the 2 types of internal energy?
- kinetic
- Chemical
what is the equation for the change in Thermal energy?
ΔE=m×c×ΔT
(The change in internal energy equals the mass times the specific heat capacity times the temperature change)
what is the specific heat capacity of a body (object) object?
the energy needed to increase the temperature of one kilogram of the body by 1°C.
If the change in internal energy = 100J, mass = 10kg, and temperature change = 1°C, what is the specific heat capacity?
10
what is the equation for specific heat capacity?
Specific heat capacity = change in internal energy / (mass (kg) x maximum temperature rise (°C) ).
The specific heat capacity of a substance is the amount of energy needed to increase the ……………. of 1 kg of that substance by 1 °C.
temperature
State the difference between thermal capacity and specific heat capacity.
- Heat capacity is a measure of the energy needed to change the temperature of an object by 1°C,.
- The specific heat capacity is the energy needed to change the temperature of a kilogram of material by 1°C.
what is the equation for thermal (heat) capacity?
C = m x c
(The thermal capacity of a body is equal to the mass multiplied by the specific heat capacity)
the change in an objects internal energy is the product of which 3 things?
- temperature change
- specific heat capacity
- mass of the object
how is infra-red measured?
by using a thermopile
What experiment can we use to measure the effectiveness of different materials as thermal insulators?
Leslie’s Cube
A glass jar has a metal lid that’s difficult to unscrew. Why does holding the jar under a hot tap help to open the lid?
the metal expands at a greater rate than the glass for the same temperature increase and this loosens the lid
The chemical energy that contributes to internal energy comes from the ………… energy stored in the ……………. between particles.
- potential
- bonds
Explain how Leslie’s cube works.
- Leslie’s cube is a metal box with 4 different colour sides (black, matt black, white, unpainted).
- If you pour hot water into the cube, the matt (dull) black side will emit more infra-red radiation than the other sides, because dull black surfaces are the best emitters of heat.
- The infra-red radiation emitted is measured using a thermopile (a sensitive thermometer).
what is the equation for energy change for change of state?
E = m x l The energy (taken in or given out in a change of state) is equal to the mass multiplied by the specific latent heat.
What are the units of latent heat of vaporisation?
J/kg
what is latent heat?
Latent heat is the energy that is transferred to a substance without the substance’s temperature changing. This happens when a substance is changing state.
what is melting also sometimes called?
Fusion
what is boiling also sometimes called?
Vaporisation
for some materials, ……………… point is the same as its condensing point
boiling
for some materials, ………………….. point is the same as its freezing point
melting
why isn’t latent heat measured?
- if we measure using the change in temperature, this energy transfer will not be measured
- the energy is transferred without the temperature changing
what is SPECIFIC latent heat?
- the latent heat per 1 kg of mass
- it is a way to standardise across objects that have different masses
where does latent heat go?
when a substance changes state, the energy is absorbed to either create or weaken bonds, rather than transfer kinetic energy to a substance’s particles
E = m x l
The …………….. (taken in or given out in a change of state) is equal to the ………………. multiplied by the specific latent heat.
- energy
- mass
What is another term for melting point?
fusion temperature
How can you detect latent heat?
using a joulemeter and measuring the energy supplied to change state
What happens to the energy supplied during a change of state at both the melting and boiling points?
kinetic energy remains constant whilst the potential energy increases
what is the equation used to work out the specific latent heat of fusion?
specific latent heat = energy change ÷ mass
what piece of equipment do we use to measure the latent heat of fusion (melting) of water/ice?
joulemeter
Latent heat is the energy that is transferred to a substance, without changing that substance’s ……………….. This happens when a substance is changing …………………
- temperature
- state
what is the equation used to work out the specific latent heat of vaporisation?
specific latent heat = energy change ÷ change in mass
To measure the specific latent heat of vapourisation of water, we must …………. water to form water vapour.
boil
To calculate specific latent heat, what do we divide the latent heat by?
mass
why do solids have fixed shapes?
because they have strong forces between the particles
why can’t solids be compressed?
because their particle are already very close together and cannot flow
how are the particles in a solid arranged?
in an ordered pattern
how do the particles in a solid move?
they move around (Vibrate) around a fixed point
why can gases be compressed?
because their particles are very far apart
what are 3 properties of gas?
- can flow
- no fixed shape
- fills its container
how do the particles in a gas move?
move randomly and are not at all organised
Why can’t liquids be compressed?
because their particle are already very close together
how do the particles in a liquid move? how does this allow liquids to flow and take the shape of their container?
the particles are in contact with each other but can still move
how are particles in a liquid arranged?
in a disordered pattern
what happens when you increase the temperature of gases?
kinetic energy increases
The change in momentum is equal to the force multiplied by time. It is also the same as ………………
impulse
what is the equation for change in momentum?
change in momentum = force x time
As you increase the temperature of a gas, its particles get more kinetic energy and move …………..
faster
If we increase the temperature of the gas in a balloon, the balloon will…
expand
A student says that a gas exerts pressure on a container because of the particles colliding with one another in the container, and the particles colliding with the walls of the container.
Is the student correct?
- This is not completely correct.
- The collisions between particles do not exert (apply) pressure. This is because their net (average) effect is 0.
- Particles do create pressure when they c-collide with the walls.
The pressure of a gas produces a net force (the sum of all the forces) at ………….. angles to the wall of a container
right
pressure x volume =…………
constant
Doing work on a gas increases the gas’ internal ……………. This increases the ……………….. of the gas.
- energy
- temperature
