atoms, elements and compounds Flashcards
what is an atom?
smallest part of an element
whats a compound? can they be separated?
2 or more substances chemically combined together, can only be separated into elements by chemical reaction
what is a mixture?
2 or more elements or compounds not chemically combined together.
how can mixtures be separated?
through filtration, crystallisation, simple distillation, fractional distillation, chromatography.
what did the discovery of the electron lead to?
the plum pudding model (ball of positive charge with negative electrons embedded in it)
what did the results of the alpha particle scattering experiment lead to?
the mass of atom was concentrated at the nucleus, and the nucleus was charged.
how did niel bohr adapt the nuclear model?
electrons orbit the nucleus at specific distances, theoretical calculations of bohr agreed.
whats the charge of a proton, neutron and electron?
1, 0, -1
whats the relative mass of a proton, neutron, electron?
1,1, very small.
what are the proton and neutron sum?
the mass number
whats an isotope?
same number of proton different number of neutrons
what are the elements in the periodic table arranged in order of?
atomic (proton) number, elements with similar properties are in groups
what were elements arranged by before discovery of protons neutrons and electrons?
order of their atomic weights, gaps left (mendeleev)
what made it possible to explain why order based on atomic weights wasnt correct?
knowledge of isotopes
what are group 0?
noble gases