Y9 Chemistry - atom models

Dalton’s model(atoms…spheres…structure)

atoms are tiny solid spheres with no internal structure

Thomson’s plum pudding model(atoms are a ball of … with … embedded inside)

atoms are a ball of positive charge with electrons embedded inside

Reason plum pudding existed(discovery of the … showed … weren’t …)

discovery of the electron showed atoms weren’t solid spheres

Rutherford’s nuclear model(atoms have a … with … orbiting around)

atoms have a tiny dense positive nucleus with electrons orbiting around

Gold foil experiment(most … particles … (atoms mostly empty space) some…(positive…), few … (nucleus is …)

most alpha particles passed through (atoms mostly empty space), some deflected (positive nucleus), few bounced back (nucleus is tiny and dense)

Problem with Rutherford’s model(orbiting … energy and … into the nucleus making atoms …)

orbiting electrons would lose energy and spiral into the nucleus, making atoms unstable

Bohr’s model(electrons orbit … lose energy)

electrons orbit in fixed energy levels where they cannot lose energy

Reason for energy levels(fixed energies stop … making atoms …)

fixed energies stop electrons spiralling into the nucleus, making atoms stable

Evidence for Bohr(his model…spectra)

his model matched observed atomic emission spectra

Chadwick’s discovery(identified…nucleus)

identified the neutron in the nucleus

Reason neutron discovery mattered(explained… in the nucleus and improved the …)

explained missing mass in the nucleus and improved the nuclear model

Modern atomic model(nucleus contains …, … in shells around it)

nucleus contains protons and neutrons, electrons in shells around it

Why models changed(new … forced scientists to …)

new experimental evidence forced scientists to update their ideas.

Which model had spiralling problems

Rutherford nuclear model

Which model had it all correct, apart from no neutrons

Bohr model

Which model had spheres with no internal structure

Dalton model

Why was plum pudding model rejected

Gold foil experiment