YR 9 - Atomic Structure Flashcards
what is an atom?
an atom is the smallest part of an element that exists.
how many elements are there?
there are about 100 different elements.
what is a compound and how are they formed?
- a compound is two or more elements that are chemically bonded together
- compounds are formed when elements chemically react together
what is a mixture?
a mixture is two or more elements that are not chemically bonded together
what do chemical equations show?
chemical equations show the reactants (what u started with) and the products (the result of a chemical change) in a reaction.
what are symbol equations?
symbol equations are balanced meaning there is the same number of each type of atom on both sides of the equation.
what is the law of conversation of mass?
the law of conversation of mass states the total mass of the product formed in a reaction is equal to the total mass of the reactants
what are state symbols ?
the state symbols used are solid (s), liquid (l), gas (g) and aqueous solutions (aq) which is when substances are dissolved into water
how can mixtures be separated?
mixtures can be separated through physical processes such as:
> filtration
> simple distillation
> fractional distillation
> chromatography
> crystallisation
this can also include evaporation
what is filtration?
filtration is the separation of insoluble solids from soluble liquids using filter paper which collects the remaining solid insoluble particles known as residue
what is crystallisation?
crystallisation is the separation of soluble substances from solvents or a solution using evaporation.
• heating to remove the water, leaving crystals behind
what is a miscible?
miscible describes liquids that dissolve in each other, mixing completely
what is simple distillation?
simple distillation is the separation of solvents from a solution.
• solution is boiled to evaporate the solvent
• vapour is then cooled and condenses
• the liquid is collected
what is fractional distillation?
fractional distillation is the separation of miscible liquids that have different boiling points.
what is chromatography?
chromatography is the separation of a mixture of substances dissolved in a solvent which have different solubilities than the solvent
• this is seen as they move up a piece of chromatographic paper
what did JJ Thompson’s model suggest?
the plum pudding model suggested that the atom was a solid ball of positive charge with negative charges randomly embedded in it.
what were the results of Ernest Rutherford’s experiment?
the results from the alpha particle scattering experiment led to the conclusion that the mass of an atom was concentrated at the centre (nucleus) and the nucleus was charged containing dense positively charged protons. there was empty space and electrons orbited/surrounded the nucleus.
what was the last subatomic particle to be discovered and why?
the neutron was the last subatomic particle to be discovered as it had no charge.
what are the subatomic particles?
the three subatomic particles are protons, neutrons and electrons.
what charge do the subatomic particles have?
• protons have a relative charge of 1+ - they are positively charged
• electrons have a relative charge of 1- - they are negatively charged
• neutrons don’t have a relative charge - they are neutral
what two subatomic particles are normally equal to each other?
in an atom, the number of electrons is equal to the number of protons
what is the overall charge of an atom and why?
atoms have no overall electrical charge because there is the same number of negatively charged electrons as positively charged protons. the charge cancels.
what is the atomic number?
the number of protons in an atom of an element is its atomic number.
how do atoms differ between different elements and a particular element?
• all atoms of a particular element all have the same number of protons whilst atoms of different elements have different numbers of protons
