C1 - Particles Flashcards
What are the 3 states of matter
Solid
Liquid
Gas
what is the particle model
- the particle model describes how particles are arranged and how they move in solids, liquids and gases
describe the arrangement + movement of particles in solids
- particles are packed very close together in a regular arrangement
- particles vibrate in fixed positions
describe the arrangement + movement of particles in liquids
- particles are close together but able to move past each other (random arrangement)
- particles vibrate + move around each other
describe the arrangement + movement of particles in gases
- particles are far apart with no regular arrangement (random arrangement)
- particles vibrate + move freely at high speeds
how do the relative energies of particles in the 3 states of matter compare
- particles in solids have the least amount of energy
- particles in gas have most energy
what are physical changes
- when a substance changes state or shape
> no new substances are made
> many physical changes can be reversed
what are chemical changes
- when a change produces one or more new substances
> many chemical changes are difficult or impossible to reverse
what happens to particles when a substance changes state
- they stay the same, but their arrangement and movement change
what happens to particles during chemical changes
- particles break up + join together in different ways
> that’s why new substances are made
what is the smallest particle that makes up a substance
atoms
what are forces between particles called
- electrostatic forces of attraction between positive + negative charges
> the forces become weaker the further apart the particles are
what are limitations of the particle model
- doesn’t take into account:
> the forces between particles
> the size of particles
> the space between particles
describe what happens in terms of particles when solids are heated + melts into liquid
- 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
describe what happens in terms of particles when a liquid is heated and evaporates into a gas
- 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
why do solids, liquids and gases expand when heated
- when heated, the molecules vibrate faster
> this causes the space between atoms to increase
what are elements + compiunds
- elements are substances made up of one type of atom
- compounds are made up of atoms of different elements
what is a molecule
- a molecule is made from two or more atoms joined together by attractive forces called chemical bonds
what are the relative mass + relative charges of the subatomic particles
- proton = 1 = +1
- neutron = 1 = 0
- electron = 1/2000 = -1
what are the subatomic particles in the atom
- protons
- neutrons
- electrons
what is the atomic number of an element
- the number of protons
> and also electrons as every atom has equal num of protons + electrons
what is the mass number of an element
- total number of protons + neutrons
- mass number = num of protons (atomic number) + num of neutrons
what are isotopes
- atoms with the same number of protons + electrons but diff number of neutrons
> they have same atomic number but diff mass number
why do isotopes of an element have identical chemical properties
- because the have the same number of electrons
