Atomic Theory & electronic structure Flashcards
What did J.J Thomson do?
- Measured the charge/mass ratio of cathode rays
- Creates the plum pudding model
- Discovered electron
What did Johnstone Stoney do?
Suggested the name electron in 1891
What colour flame does strontium produce?
Red
What did William Crookes prove?
Cathode rays travelled in straight lines
What did Robert Millikan do?
- Oil drop experiment- allows charge of electron to be measured accurately
What did James Chadwick prove?
Existence of neutrons
What did Rutherford prove?
- Existence of the nucleus and protons
2. Atoms was mostly empty space
What was the plum pudding model?
First model of atom. Atom consisted of a (+) sphere w/ electrons randomly distributed inside it.
What did John Dalton prove?
- Atoms are small indivisible particles
- Atoms of an element are identical
- Atoms of different elements vary in mass
- A compound contains atoms of 2 or more elements
What is atomic number?
No. of protons in the nucleus (z)
What is mass number?
Sum of the no. of neutrons and protons in the nucleus (A)
What are isotopes?
Atoms with the same no. of protons but different no. of neutrons
What colour flame does potassium produce?
Lilac
What is relative atomic mass?
Average mass of an atom relative to one-twelfth the mass of an atom of carbon-12 (Ar)
What colour flame does sodium produce?
Yellow
What is an energy level?
A region of definite energy within the atom that electrons can occupy
What is the hydrogen emission spectrum called?
The Balmer series
What does Bohr’s theory show?
- Electrons occupy fixed energy levels
- Electrons occupy lowest available energy level (ground state)
- Electrons can move to higher energy levels if they gain energy (excited state)
- Excited states are unstable, electrons will return to ground state
- When this happens, a photon of light is emitted
What are the problems with Bohr’s theory?
- Wave/particle duality
- Heisenberg’s uncertainty principle
- Sub-levels and orbitals
- Only applies to hydrogen
What is the Heisenberg uncertainty principle?
States that it is impossible to know both the exact position and velocity of an electron at the same time
What is an atomic orbital?
A region where the probability of finding an electron is high
What colour flame does barium produce?
Yellow-green
What are the types of orbitals?
S
Px
Py
Pz
What colour flame does lithium produce?
Deep red
What were the observations made of Rutherford’s gold foil experiment?
- Most particles travel through the foil undeflected
- Some particles are deflected at small angles
- Occasionally, a particle travels back from foil
What did Rutherford interpret from the gold foil experiment?
- Atom is mostly empty space
- Nucleus is positively charged
- Nucleus carries most of the atom’s mass
- Nucleus is small and dense
What colour flame does copper produce?
Blue-green
What shape is a s orbital?
Spherical
What shape is a p orbital?
Infinity symbol
What is an energy sublevel?
A subdivision of an energy level containing one or more atomic orbitals, all of which have the same energy
What is the aufbau principle?
States that:
1) . Electrons will occupy the lowest energy sublevel available
2) . Only 2 electrons can occupy an orbital at the one time
3) . Electrons tend to occupy orbitals of equal energy singly where possible.
What is the first ionisation energy?
The first ionisation energy of an element is the minimum energy in kilojoules required to remove the most loosely bound electron from each isolated atom in a mole of the element in its ground state.
What is the second ionisation energy?
The second ionisation energy of an element is the minimum energy required to remove the most loosely bound electron form each singly charged positive ion in a mole of these ions.
