CC1-Key Concepts In Chemistry Flashcards
What is the Dalton model?
Billiard ball: solid spheres
What is JJ Thomson’s plum pudding model?
A sphere with electrons in a positively charged ‘pudding’- positive charge was thought to be spread out far
What was Rutherford’s gold foil experiment and what did it show?
He fired positively charged alpha particles at thin gold foil
Expected them all togo through as he thought positive charge was spread far out and not likely to repel particles
HOWEVER
Some deflected at an angle and some were deflected backwards completely because they were repelled by a positive charge, the nucleus
Most passed through because of the atom’s vast space
What was Rutherford’s model
A ‘cloud’ of electrons surrounding a positively charged nucleus
Why is Rutherford’s model wrong?
If the positive nucleus was surrounded by a cloud of electrons the electrons would be attracted to the nucleus causing the atom to collapse
What is Bohr’s model?
The atoms are in fixed orbits in different shells surrounding the nucleus and each shell has a different fixed energy
Charge and relative mass of subatomic particles
Proton: +1
1
Neutron: 0
1
Electron: -1
1/2000
Why do atoms have the same amount of protons and electrons?
The same positive and negative charges balance/cancel each other out so the overall net charge of an atom is 0
How big is the nucleus relative to the size of the atom
Very small: there is a lot of space in the atom
Where is mass concentrate din the atom?
The nucleus
What is the mass number?
Number of protons and neutrons in an atom. It is also equal to its Ar
Isotopes
Isotopes are different atoms of the same element with the same number of protons (atomic number) but a different number of neutrons (mass number)
