Physics: Atomic Physics

gold foil experiment

positively charged alpha particles are two protons into neutrons bound together emitted from the nucleus of atoms during radioactive decay.

A beam of alpha particles are fired at the thin sheet of

gold foil

most of the alpha particles ____ through the gold foil and somewhere deflected at large angles or even straight back

passes

due to the angles of deflection, Rutherford concluded that there must be a concentration of positive charge at the centre of the atom,like charges ___

repel

ernest rutherford

in 1911 conducted the famous gold foil experiment, discovering the nucleus and creating the planetary model of the atom

discovered the ___ nucleus of the atom

positive

atoms are mostly

empty space

proposed that electrons ___ the nucleus as planets orbit the sun; the planetary model of the stom

orbit

unable to determine why electron orbits that steadily decreased to loss of ____ caused by centripetal acceleration and electromagnetism concepts of physics.

energy

further experimentation by other scientist led to a more _____ and _____ atomic model

accurate, detailed

Niels Bohr

in 1913 proposed a new model of the hydrogen atom that also explained atomic spectra

like rutherford, electrons orbit in _____ _____ around the nucleus

circular paths

_______ forces between positive protons and negative electrons were what kept the electrons in orbit

electrostatic

only specific fixed orbits are allowed; electrons are not found between these _____

orbits

ground state

electrons at their lowest and most stable energy level

excited states

electrons that have absorbed energy and move to a higher less stable energy level

atomic spectra

the spectrum of electromagnetic radiation emitted or absorbed by an electron during transitions between energy levels in an atom

this phenomenon was discovered during experiments with ______ ray tubes

cathode

cathode ray tubes

glass tubes filled with an elemental gas would light up when an electric current passed through it

jj thompson’s discover of the _______ in 1897 used cathode ray tubes

electron

the beam of ______ particles within the cathode ray tube would bend toward positive charges and _____ from negative; electrons must be negative because opposites attracted and like repel

charged, away

spectroscopy

is the study of emission and absorption of electromagnetic radiation of elemental gases and can be used to analyze elements within a mixture

emission spectrum

a diagram or graph that indicates the wavelength of electromagnetic radiation (light) a substance emits

every element has a unique ____ _____

emissions spectrum

absorption spectrum

a diagram or graph that indicates the wavelength of electromagnetic radiation (light) a substance absorbs