Topic 1 - Atomic Structure/Periodic Table Flashcards
What is an element?
A single type of atom
What is a compound
Two or more different elements that are chemically bonded
What is a molecule?
Two or more of the same atoms held together by a chemical bond
What are shells filled with?
Inside lowest energy electrons first, with energy increasing further out the shell
Why was Mendeleev famous?
Because he left gaps for elements which had not yet been discovered, he predicted their properties
What are atoms
Tiny particles of matter which make up eveytbying in the universe
What was John Dalton’s theory?
He thought atoms were solid spheres and different spheres made up different elements
What was JJ Thomson’s theory?
He didn’t think atoms were solid spheres
He measured the charge and mass of the atom and this showed that the atom contained smaller negatively charged particles
How did Rutherford conduct his gold foil experiment?
He fired positively charged alpha particles at a thin sheet of gold foil, he expected the particles to mostly pass through due the positive charge being spread out throughout the atom however small number of particles were deflected
Why were particles deflected but some weren’t in the gold foil experiment?
Most of the particles passed through empty space however some were deflected by the nucleus which is of the same charge as the alpha particles
What was Rutherford theory?
His theory was the nuclear atom
In this there’s a positively charged nucleus in the centre surrounded by a cloud of negative electrons
Why wouldn’t Rutherford theory work?
Because if there was a cloud of electrons around the nucleus, they would be attracted to it causing the atom to collapse therefore it was clear that electrons had to be contained in shells
What is the mass of a proton?
1
What is the mass of a neutron
1
What is the mass of an electron?
0.0005
