topic 1 Flashcards
what is a compound
2 or more elements chemically bonded together in fixed proportions
what is an elemenet
a substance made up of the same atom
what is a molecule
any elements chemically bonded together even if theyre the same atom
what is a mixture
2 or more elements not chemically bonded together
what is the relative atomic mass and charge for electron proton and nuetron
electron- -1 charge and very small mass
nuetron- 0 charge and 1
proton- +1 charge and 1
what is an isotope
different forms of the same element that have the same number of protons but different number of neutrons
what is an ion
atoms with an overall charge due to the loss or gain of electrons
what are the physical seperation techniques
crystallisation, simple distillation, fractional distillation, filttration, paper chromoatgaprhy
when is filtartion used
used to seperate an insoluble solid from a liquid
when is fractional and simple distillation used
fractional distillation-used when you want to seperate a mixture of liquids with different boiling points
simple distillation- when you want to seperate a solid from a liquid and keep the liquid at the same time
when is crystallisation used
used to seperate a soluble solid from a liquid
when is paper chromatography used
used to seperate substances based on different solubilties
why do we draw the starting line in pencil
because if we drew it in pen then the ink would dissolve in the solvent and move up the paper
what is the equation for relative atomic mass
100
describe the alpha scattering experiment
ernest rutherford fired a beam of positively charged alpha paricles at a sheet of gold foil. some particles went through, some deflected back and some were scattered. this lead him to conclude that the mass is concentrated at the centre of the atom, the t=centre of the atom has a positive charge and that the atom is mostly empty space
how is the nuclear model different to to the plum pudding model
the nucleus is a positive structure at the centre of the atom and theres electrons orbiting around it.
describe the properties of group1 metals
the alkali metals are soft,very reactive and have low melting and boiling points. as you go down the group, the distance from the nucleus to the outermost electron shell increases, this weakens the electrostatic attraction between the 2 resulting in the outermost electron being lost more easily
describe the properties of the group 0 elements
the noble gases are unreactive as they all have a full outer shell. they have low melting and boiling points. non flammable
describe properties of group 7 elements
the halogens have a low melting and boiling point.
reactivity decreases as you go down.
describe the properties of the transition elements
high melting, low reactivity,hard metals,useful as catalysts
