chapter 1 Flashcards
(21 cards)
what is an atom?
smallest part of an element that can exist
what is Daltons model of an atom?
atoms as solid spheres that could be not divided smaller parts
what is the plum pudding model?
sphere of positive electrons with negative electrons embedded in it
what did scientists discover in the alpha scattering experiment ?
some alpha particles were deflected by the gold foil-
this showed that an atom mass is positive and must be concentrated in one small space (nucleus)
what did scientists discover in the alpha scattering experiment ?
some alpha particles were deflected by the gold foil-
this showed that an atom mass is positive and must be concentrated in one small space (nucleus)
describe the nuclear model of the atom
dense nucleus with electrons orbiting it
what did niels bohr discover?
electrons orbit in fixed energy levels (shells)
what did James Chadwick discover?
uncharged particle is called the neutron
where are protons and neutrons?
in the nucleus
what is the relative mass of each sub-atomic particle?
proton 1
neutron 1
electron 0 (very small)
what is the relative charge of each sub-atomic particle?
proton +1
neutron 0
electron -1
how can you find out the number of protons in an atom?
the atomic number on the periodic table
how can you calculate the number of neutrons in the atom
mass number - atomic number
why do atoms have no overall charge
they have the equal numbers of positive protons and negative electrons
how many electrons would you find in the first, second, third shell
up to 2 in the first shell and up to 8 in in the second and third
what is an element?
substance made up of one type of atom
what is a compound?
substance made up of more than one atom chemically joined together
what is a mixture?
two or more substance not chemically combined
what is an isotope?
atoms of the same element with the same number of protons and different number of neutrons
what are the four physical processes that can be used to separate mixtures
filtration, crystallisation, fractional distillation, simple distillation, chromatography
what is relative mass?
the average mass of all the atoms of an element
