Atomic Structure Flashcards
1
Q
Timeline of model of the atom
A
- Democritus
- John Dalton
- J.J Thompson
- Rutherford
- Neils Bohr
- James Chadwick
2
Q
Democritus
A
- Greek philosopher
- atomos = indivisible
- atoms could not be split
3
Q
John Dalton
A
- came up with atomic theory
- all matter composed of atoms
- they are indivisible and indestructible building blocks
- represented atoms as hard spheres that couldn’t be split
- atoms of an element were identical
- different elements had atoms of different size and mass
4
Q
J.J Thompson
A
- atoms were indivisible
- discovered atoms contained negatively charged particles (electrons)
- put forward plum pudding model
- atoms were spheres of positive charge with negative electrons randomly embedded throughout
- realised when discovering electrons that atoms could not be solid spheres and could be broken down into smaller subatomic particles
5
Q
Rutherford
A
- gold foil experiment proves that plum pudding model was incorrect
- fired positively charges alpha particles through gold foil
- proved that atoms have their positive charge concentrated in a very tiny volume and that most of the atom was completely empty space
- if the plum pudding model correct, then most of the alpha particles fired at the gold foil would be deflected, but most passed straight through
6
Q
Niels Bohr
A
- if electrons were a ‘cloud’ around the nucleus then it would spiral sown into the he nucleus causing it to collapse
- thus Bohr proposed a new theory:
- electrons can only exist in fixed orbits/shells
- each shell has a fixed energy
7
Q
Niels Bohr revised model
A
- scientists discovered that not all electrons in the same shell had the same energy
- meant somehow the previous Bohr model wrong
- refined to add sub-shells/orbitals
- Bohr believed each shell can only hold a fixed number of electrons
- also, elements reactivity is due to its electrons, so when the shell is full, it is inert.
- modified Bohr model includes the idea of sub shells and orbitals and we still use this model to explain basic ideas about bonding
8
Q
James Chadwick
A
- devised an experiment to prove the existence of neutrons
9
Q
Different sub-atomic particles
A
- nucleons = protons + neutrons
- electrons
10
Q
Properties of subatomic particles
- proton
- neutron
- electron
A
11
Q
Isotopes
A
- Atoms with the same number of protons and electrons but different number of neutrons
- They have the same atomic number but a different mass number
- the reactivity of isotopes are identical as they have the same number of electrons
12
Q
Atomic number
A
The number of protons
13
Q
Mass number
A
Total number of protons an neutrons
14
Q
What affects the reactivity of an element
A
The number of electrons
15
Q
Equation for RAM
A
Ar = sum of the abundance x atomic number / total number of abundance
16
Q
Relative atomic mass (RAM) (Ar)
A
The relative atomic mass is the average mass of its atoms compared to 1/12 the mass of a carbon-12 atom
17
Q
Calculate the abundance of the different Chlorine molecules
A
18
Q
Different stages of TOF
A
- Ionisation
- Acceleration
- Flight Tube (Ion drift)
- Detection