unit 1 Flashcards
what is an atom?
smallest part of an element that can exist
what is dalton’s model of the atom?
atoms as solid spheres that couldnt be divided into smaller parts
what is the plum pudding model of the atom?
sphere of positive charge 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 an atom’s mass and positive charge must be concentrated in one small piece
describe the nuclear model of the atom.
dense nucleus with electrons orbiting it
what did Neils Bohr discover?
electrons orbit in fixed energy levels (shells)
what did James Chadwick discover?
uncharged particles called the neutron
where are protons and neutrons?
in the nucleus
what is the relative mass of each subatomic particle?
proton:1, neutron:1, electron:0(very small)
what is the relative charge of 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 an atom?
mass number - atomic number=neutrons
why do atoms have no overall charge?
equal numbers of positive protons and negative electrons
how many electrons would you place in the first, second, and third shells?
up to 2 in the first shell, and up to 8 in each of the second and third shells
what is an element?
substance made of one type of atom
