Atomic structure and the periodic table - Topic 1 Flashcards
(39 cards)
what are the relative charges of the subatomic particles
electron = -1
proton = +1
neutron = 0
what are the relative masses of the subatomic particles
electron = very small
proton = 1
neutron = 1
where is most of the mass of an atom contained
the nucleus
what does the atomic mass number tell you
the number of protons and neutrons in the atom
what does the atomic number tell you
the number of protons in the atom
what is the number of protons in an atom equal to
the number of electrons
what is an element
a substance that contains only one type of atom, with the same atomic number
what is an isotope
a different form of the same element with the same number of protons but a different number of neutrons
what does relative atomic mass mean
the average mass, taking into account all of the different masses and abundances of all of the isotopes that make up the element
how can you calculate relative atomic mass
(isotope abundance x isotope mass number) ÷ sum of abundances of all isotopes
what is a compound
substances formed by two or more elements held together by chemical bonds
what is the formula of ammonia
NH3
what is a mixture
two or more elements or compounds mixed, but not chemically bonded together
what is the method for paper chromatography
1) draw a pencil line near the bottom of a sheet of filter paper (pencil is insoluble)
2) add a spot of ink to the line and place the sheet in a beaker of solvent (i.e. water), making sure it doesn’t touch the solvent
3) place a lid on the container to stop evaporation
4) the solvent seeps up the paper and carries the ink with it, each different dye moves at different rates and so they will separate out
what is the method for separating soluble solids from solutions via evaporation
1) pour the solution into an evaporating dish
2) slowly heat the solution, the solvent will evaporate and the solution will get more concentrated
3) keep heating until all that is left is dry crystals
what is the method for crystallisation
1) pour the solution into an evaporating dish and gently heat
2) once some of the solvent has evaporated or crystals start to form, remove from the heat and let it cool
3) the salt forms crystals as it becomes insoluble in the cold, highly concentrated solution
4) filter the crystals and leave them in a warm place to dry
what is the method for filtration and crystallisation of rock salt
1) grind the mixture to make sure the salt crystals are small and will dissolve easily
2) put the mixture in water and stir, the salt will dissolve but the sand wont
3) filter the mixture to remove the sand
4) evaporate the water from the salt solution until it forms dry salt crystals
what is the difference between simple and fractional distillation
simple distillation separates a liquid from a solution, fractional distillation separates a mixture of liquids, even if their boiling points are close together
what happens in simple distillation
the solution is heated and the part that has the lowest boiling point evaporates first, the vapour is cooled and condensed in the condenser and turns back into a liquid to be collected
what happens in fractional distillation
the mixture is heated in a flask with a fractionating column on top, the mixture with the lowest boiling point evaporates first and reaches the top of the column, where the temperature matches the boiling point of the liquid, other liquids may evaporate but will cool before they reach the top, when the first liquid condenses and is collected, the temp can be increased until the next liquid reaches the top
what is the problem with simple distillation
it can only separate liquids with very different boiling points
what did john dalton describe atoms as
solid spheres that made up the different elemets
what did JJ thompson describe atoms as
the plum pudding model - atoms are solid spheres with electrons inside it
what did ernest rutherford prove in his alpha particle scattering experiment and how did he prove this
most of an atom is empty space, with its mass being concentrated in the nucleus, because when he fired alpha particles at a sheet of gold, most went straight through but some were deflected more than expected, or deflected backwards
