C1 - Particles Flashcards

1
Q

What are the 3 states of matter

A

Solid
Liquid
Gas

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2
Q

what is the particle model

A
  • the particle model describes how particles are arranged and how they move in solids, liquids and gases
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3
Q

describe the arrangement + movement of particles in solids

A
  • particles are packed very close together in a regular arrangement
  • particles vibrate in fixed positions
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4
Q

describe the arrangement + movement of particles in liquids

A
  • particles are close together but able to move past each other (random arrangement)
  • particles vibrate + move around each other
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5
Q

describe the arrangement + movement of particles in gases

A
  • particles are far apart with no regular arrangement (random arrangement)
  • particles vibrate + move freely at high speeds
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6
Q

how do the relative energies of particles in the 3 states of matter compare

A
  • particles in solids have the least amount of energy
  • particles in gas have most energy
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7
Q

what are physical changes

A
  • when a substance changes state or shape
    > no new substances are made
    > many physical changes can be reversed
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8
Q

what are chemical changes

A
  • when a change produces one or more new substances
    > many chemical changes are difficult or impossible to reverse
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9
Q

what happens to particles when a substance changes state

A
  • they stay the same, but their arrangement and movement change
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10
Q

what happens to particles during chemical changes

A
  • particles break up + join together in different ways
    > that’s why new substances are made
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11
Q

what is the smallest particle that makes up a substance

A

atoms

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12
Q

what are forces between particles called

A
  • electrostatic forces of attraction between positive + negative charges
    > the forces become weaker the further apart the particles are
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12
Q

what are limitations of the particle model

A
  • doesn’t take into account:
    > the forces between particles
    > the size of particles
    > the space between particles
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13
Q

describe what happens in terms of particles when solids are heated + melts into liquid

A
  • when heated, particles absorb thermal energy + convert it into kinetic energy
  • the particles in the solid vibrate more, causing the solid to expand until the structure breaks and the solid turns into a liquid
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14
Q

describe what happens in terms of particles when a liquid is heated and evaporates into a gas

A
  • when heated, the particles in a liquid expand
  • some particles on the surface gain sufficient energy to overcome the intermolecular forces and evaporate
  • at the boiling point, all of the liquid particles gain enough energy to evaporate
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14
Q

why do solids, liquids and gases expand when heated

A
  • when heated, the molecules vibrate faster
    > this causes the space between atoms to increase
15
Q

what are elements + compiunds

A
  • elements are substances made up of one type of atom
  • compounds are made up of atoms of different elements
15
Q

what is a molecule

A
  • a molecule is made from two or more atoms joined together by attractive forces called chemical bonds
15
Q

what are the relative mass + relative charges of the subatomic particles

A
  • proton = 1 = +1
  • neutron = 1 = 0
  • electron = 1/2000 = -1
16
Q

what are the subatomic particles in the atom

A
  • protons
  • neutrons
  • electrons
16
Q

what is the atomic number of an element

A
  • the number of protons
    > and also electrons as every atom has equal num of protons + electrons
16
Q

what is the mass number of an element

A
  • total number of protons + neutrons
  • mass number = num of protons (atomic number) + num of neutrons
17
Q

what are isotopes

A
  • atoms with the same number of protons + electrons but diff number of neutrons
    > they have same atomic number but diff mass number
18
Q

why do isotopes of an element have identical chemical properties

A
  • because the have the same number of electrons
18
Q

what are ions

A
  • charged particles
18
Q

when are ions formed

A
  • when atoms, or groups of atoms, lose/gain electrons
19
Q

who describe atoms as ‘solid sphere’

A

John Dalton

20
Q

what was Dalton’s theory

A
  • that all matter is made from atoms
  • all atoms of an element are the same
  • different elements contain different types of atoms
    > his model showed no subatomic mass - each atom was essentially a solid sphere of a certain mass
21
Q

what discovery caused Dalton’s model of an atom to change

A
  • the discovery of subatomic particles
22
Q

what did JJ Thomson discover + how

A
  • the electron in an experiment which polluted cathode rays
  • he proposed the plum pudding model:
    > atom has a weak positive sphere with negative electrons embedded into it
    > atoms are neutral overall
23
Q

what experiment did Rutherford (alongside Geiger and Marsden) carry out

A
  • gold foil experiment:
    >fired a source of alpha particles at thin gold foil
    > they found that most particles went through
    > but some were slightly deflected
    > some even came straight back
24
Q

what did Rutherford conclude from his gold foil experiment

A
  • that the atom has a positively charged nucleus containing most of its mass which is very small and dense as alpha particles could pass through atom
  • around the nucleus must be negative electrons
    > most of the atom is empty space
25
Q

what did Bohr find out + how

A
  • that electrons orbit on shells
    > after realising that electrons would be attracted to the positive nucleus and that the atom would collapse he showed electrons to occupy fixed energy levels / shells
26
Q

who founded the existence of neutrons

A
  • James Chadwick
27
Q

compare the sizes of the nuclear radius and the atomic radius

A
  • nuclear radius is much smaller than atomic radius
28
Q

compare the typical size of atoms and small molecules

A
  • atoms and small molecules are incredibly small
    > small molecules are larger than atoms because they are mode of atoms
  • the typical atomic radii and bond length are in the order of 10-10m
29
Q

what is the size of nanoparticles

A
  • 1nm to 100nm in size