C1 - atomic structure Flashcards
how many elements are there
around 100
what do the symbols in the periodic table represent (e.g. Mg, O, Na)
the different elements
how is the periodic table organised
in groups (columns)
what are the elements that lie next to the step line called
metalloids
what are word equations used for
to see which substances are used
what are symbol equations used for
to show how much of each substance is involved
what is the law of conservation of mass
the total mass of products formed in a reaction is equal to the total mass of the reactants
balance H2 + O2 -> H2O
2H2 + O2 -> 2H2O
what are the separation techniques
filtration
crystallisation
distillation
chromatography
what is filtration used for
separating substances that are insoluble in a particular solvent from those that are soluble in the solvent
what is crystallisation used for
separating a soluble solid from a solvent, e.g. obtaining a salt from a salt solution
what is distillation used for
collecting the solvent
how does fractional distillation work
by using a fractionating column containing glass beads, you boil the miscible liquids, the substances with the higher boiling point will condense more readily on the cooler glass beads at the bottom and drip down into the flask beneath, the lower boiling point substances will continue rising and pass into the condenser
what is paper chromatography used for
separating (and identifying) substances from mixtures in a solution
describe the process of chromatography
a capillary tube is used to dab a spot of the solution on a pencil line near the bottom of a sheet of chromatography paper. the paper is then placed standing in a solvent at the bottom of a beaker. the solvent is soaked up through the paper running through the spot of the mixture.
what is the history of the discoveries of the atom
1897 PLUM PUDDING MODEL - JJ Thompson and the ELECTRON
1909 NUCLEAR MODEL - Ernest Rutherford and the NUCLEUS with PROTONS
1914 BOHR MODEL - Niels Bohr with the ELECTRONS IN SHELLS
1932 - James Chadwick with NEUTRONS
what was jj thomsons experiment to discover the electron
applied high voltages to gases at low pressure using beams of particles, which were attracted to a positive charge
what is the relative charge and mass of each subatomic particle
proton: +1, 1
neutron: 0, 1
electron -1, negligible
what is the atomic and mass number
atomic number - number of protons in each atom
mass number - number of protons + neutrons in nucleus
what is an ion
an ion is a charged atom, either positively or negatively depending on whether it has lost or gained an electron
what is an ion
an ion is a charged atom, either positively or negatively depending on whether it has lost or gained an electron
what is an isotope
an isotope is an atom with different numbers of neutrons
what is a property of some isotopes
radioactive (unstable)
how many electrons can each shell hold
1st - 2
2nd - 8
3rd - 18
4th - 32
what happens when group 1 elements are added to water
they form a hydroxide and hydrogen
e.g. lithium + water -> lithium hydroxide + hydrogen
what was rutherfords experiment to discover the nucleus
fired positively charged alpha particles through gold foil, suggesting the mass of an atom is concentrated at its centre, and is positively charged
what was bohrs experiment to discover electron shells
noticed light given out when atoms were heated only had specific amounts of energy, suggesting must be at fixed differences
what was james chadwicks experiment to discover neutrons
did experiments to prove existence of neutrons (they had to exist to make up for lost mass in atom)
how can you tell the solubility of solvents in chromatography
how far they are carried up the paper.
