C1 Atomic Structure Flashcards
What is an atom?
The smallest part of an element that can still be recognised
What is an element?
A substance which contains only one type of atom
What is a compound?
A substance which contains more than one type of atom
 what is the structure of an atom?
An atom has a tiny nucleus at its centre, surrounded by electrons
What is periodic table?
An arrangement of elements in order of their atomic number, forming groups and periods
What is the law of conservation of mass?
No new atoms are ever created or destroyed in a chemical reaction
What is a reactant in a reaction?
A substance we start with before a chemical reaction takes place
What is a product in a reaction?
A substance made as a result of a chemical reaction
What is a balanced symbol equation?
A symbol equation in which there are equal numbers of each type of atom on either side of the equation
What are state symbols?
The abbreviations used in balance symbol equation to show if the reactants and products are solid, liquid, gas or dissolved in water
What is an aqueous solution?
The mixture made by adding a soluble substance to water
What is a mixture?
A mixture is made up of two or more substances that are not chemically combined together
What is filtration?
The technique used to separate substances that are insoluble in a particular solvent from those that are soluble
What is crystallisation?
When a solvent is evaporated away from the solute
What is simple distillation?
Separation of a liquid from a mixture by evaporation followed by condensation
What is fractional distillation?
A way to separate liquids from mixture of liquids by boiling of the substances at different temperatures, then condensing collecting the liquids
What is paper chromatography?
The process whereby small amounts of dissolved substances are separated by running a solvent along a material such as an absorbent paper
This is based on their different solubilities.
What did the ancient Greeks and John dalton think about the structure of the atom?
They were tiny hard spheres and each chemical element has its own atom
what can speed up crystallisation?
Gently heating the solution
what factor affect fractional distillation?
how close the boiling points of the liquids are.
why are all separation techniques physical processes?
they do not involve chemical reactions and no new substances are made
what is the paper called in paper chromatography?
the stationary phase as it does not move
what is the solvent called in paper chromatography?
the mobile phase as it moves along the paper.
why does paper chromatography work?
Each chemical in the mixture is attracted to the stationary phase to a different extent
what do pure chemicals produce in all solvents in paper chromatography
a single spot
what does a mixture produce in paper chromatography?
different spots depending on the solvent
Why is the starting line drawn in pencil in paper chromatography?
If the line was drawn in pen, the ink would move up the paper with the solvent.
what is the structure of the plum pudding model?
a sphere of positive charge with negative electrons embedded in it.
why did scientists use gold foil in the alpha scattering experiment?
it can be hammered out very thin to just a few atoms thick.
what can you tell about the structure of the atom if most of the alpha particles passed through the gold foil?
that atoms are mostly empty space
if some alpha particles were deflected, what does this show about the structure of the atom?
there is a dense area of positive charge. Alpha particles which came close to this area were repelled and changed direction.
if some alpha particles bounced straight back, what does this show about the atom?
the centre of the atom contains a great deal of mass
what did Niels Bohr discover?
That electrons orbit the nucleus at specific distances called energy levels.
what causes the positive charge in the nucleus of an atom?
positively charged protons
what did James Chadwick discover?
neutral particles called neutrons in the nulceus
why do atoms have no overall charge?
there is an equal number of electrons and protons.
what is the radius of an atom?
0.1 nm or 1 x 10^-10 m
what is the radius of the nucleus of an atom?
1 x 10^-14 m
what is the atomic number?
the number of protons in an atom
what is the mass number?
the total number of protons and neutrons
what is are isotopes?
atoms of an element with different numbers of neutrons
what is are ions?
atoms with an overall charge. this is because they have gained or lost electrons
what is the relative atomic mass?
the average of the mass numbers of the different isotopes
it is weighted for the abundance of each isotope
what is the formula for relative atomic mass?
relative atomic mass = (mass isotope 1 x % abundance) + (mass isotope 2 x % abundance) / 100
how do electrons exist?
in electron energy levels or shells
what are the maximum number of electrons each energy level can hold?
first - 2 electrons
second and third - 8 electrons
fourth - 18
