Topic 1 - Moles Flashcards
Elements
cannot be broken down by any chemical process into simpler substances
Atoms
the smallest part of an element
Compounds
contains more than one element combines chemically in a fixed ratio
Mixtures
components are not chemically bonded together. elements retain their individual properties
Homogenous
mixture is uniform in composition throughout and consists of one phase
Heterogenous
mixture with a non-uniform composition throughout and consists of separate phases
Solid
- fixed shape
- fixed volume
- held by intermolecular forces in a fixed position
- vibrate about a fixed point
- do not have translational velocity
Liquid
- fixed volume
- takes up shape of container
- held closely by intermolecular forces
- have translational velocity fo diffusion can occur
- can form vapour when pressure of vapour = pressure above the liquid. this is boiling
Gas
- widely spaced
- pressure due to particles colliding with container
- intermolecular forces are negligible
- volume occupied by each molecule is negligible
- particles move with rapid, random motion so diffusion can occur
Avogadro’s constant
12.00g of carbon-12 contains 6.02 times 10^23 atoms
What is a mole
a mole is the amount of substance that contains 6.02 times 10^23 particles of that substance
Relative atomic mass
the wighted mean of all the naturally occurring isotopes of an element relative to carbon-12
Empirical formula
shows the simplest whole number ratio of atoms of each element in a particle of the substance
Molecular formula
actual number of atoms of each element in a molecule of the substance
Ideal gas
- no volume of molecules and no forces between
- volume at a certain temperature and pressure depends on the number of particles present and not the nature of gas
