Structure 1.1 Flashcards
Pure substance
Made up of only one chemical element or compounds made of two or more elements - has a definite and constant composition
Chemical element
A substance that can’t be broken down into simpler substances, consists of atoms containing the same number of protons
Compound
A pure substance formed when two or more elements are chemically bonded.
Solid (s)
Occupy a fixed space and volume. Particles are held closely together in a lattice.
Liquid (l)
Fixed volume that takes the shape of the container. Particles are close together but move randomly.
Gas (g)
Completely fills the container, particles are widely spaced and move rapidly and randomly.
Heat
A measure of total energy in a substance. Depends on the mass of the substance. Measured in joules
Temperature
Measure of average kinetic energy “hotness”. Measured in kelvin (K)
When does water boil?
When the vapour pressure is equal to the atmospheric pressure. Lowering pressure lowers the boiling point.
Lattice
Repeating 3-D arrangement of atoms/ions/molecules in a crystal
Kinetic theory of matter - changes of state
In solid, lattice structure. Once heated, particles have sufficient energy to break the lattice and become liquid. Heat is added and particles move faster, have enough energy to overcome attractive forces and escape as a vapour.
Melting
Solid to liquid
Freezing
Liquid to solid
Vaporization
Liquid to gas
Evaporation
Liquid to gas below boiling point - particles at the surface gain enough energy to escape as a vapour
Boiling
Liquid to gas at boiling point, when external pressure is equal to vapour pressure (all particles gain enough energy to turn to vapour)
Condensation
Gas to a liquid
Sublimation
Solid to gas without passing through the liquid state
Deposition
Gas to solid without passing through the liquid state
Cooling curve - why is temperature constant for about 8 minutes?
Equilibrium is formed between heat given out due to formation of attractive forces and heat lost to environment exothermically.
What is one mL and one L
mL = cm^3
L = dm^3
Solute
Substance being dissolved
Solvent
Liquid that dissolves the solute
Solution
When a solute dissolves in a solvent
Soluble
Substance that can dissolve in a solvent
Insoluble
Substance that cannot dissolve in a solvent
Miscible
Two liquids that can dissolve into each other
Immiscible
Two liquids that cannot dissolve into each other
Homogenous
All components in the same phase of matter
Heterogenous
Components in different phases of matter
Mixture
Combination of pure substances, has no definite or constant composition
Filtration
Seperates solid particles from a liquid
Solvation and evaporation
Mixture is warmed with a solvent, filtered to remove insoluble particles and evaporated
Recrystillisation
Mixture is dissolved in solvent, heated, cooled and crystals are isolated by filtration (less soluble substance)
Distillation
Used to seperate liquids from less volatile liquids or dissolves components based on boiling points
Chromotography
Spot of mixture is placed on paper, and solvent rises up the paper
Which atom doesn’t have a nucleus composed of neutrons and protons?
Hydrogen
Which atom doesn’t have a nucleus composed of neutrons and protons?
Hydrogen
What is relative atomic mass?
The weighted mean of the naturally occurring isotopes of the element relative to the C-12 atom
What is the difference between relative atomic mass and atomic mass?
Atomic mass is the sum of protons and neutrons in the nucleus, and relative atomic mass is the weighted mean of natural isotopes of the element
Nucleon
Protons and neutrons in the nucleus
Radioisotope
The unstable form of an element that emits radiation to transform into a more stable form
Relative abundance
Percentage of an isotope in a naturally occurring sample of the element
Each element produces an emission spectrum - what is this?
Discrete lines at particular wavelengths corresponding to the differences between energy levels.
Movement of electrons between shells is called what?
Electron transititions
How can you tell the relative energy of a shell?
Energy emitted from electron transititions can be detected and wavelength measured
What electron transitions produce UV light?
n=7/6/5/4/3/2/ to n=1
Which electron transmitions produce infrared light
n=7/6/5/4 to n=3/4/5/6
