Atomic Structure 1.1 Flashcards
Developing ideas of the atom
1803
John dalton
Atoms couldn’t be broken down
Developing ideas of the atom
1896
Henri becquerel
Electrons have a negative charge and proton has a positive charge
J Thomson
Discovered electrons
Developing ideas of the atom
1911
Ernest Rutherford
Most of the mass and all the positive charge was in the Center the nucleus
Arrangement of sub-atomic particle
Proton and neutrons are held in the centre by a strong nuclear force stronger than the electrostatic force between protons and electrons
Atomic number
Proton number
Mass number
Protons + neurton
Isotope
- Atoms with the same number of protons but a different number of neutrons
- react chemically exactly the same ( same electron configuration)
Caron dating
Radioactive isotopes have a half life ( the time taken for half of its radioactivity by half)
Carbon-14
Half life of 5730 years
Date organic matter
Decays at a constant rate
Electron shells
First shell
2
Electron shells
Second shell
8
Electron shells
Third shell
18
Relative atom mass
1/12 of 1 atom of 12C
Relative molecular mass
1/12 of 1 atom of 12C
Mass spectrometer
Vacuum
High vacuum to prevent ions that are colliding with molecules from the air
Mass spectrometer
Ionisation
Dissolved in a volatile solvent and forced through a fine hollow needle that is connected to the positive terminal
Ion that have lost their electron.
Mass spectrometer
Acceleration
Positive ions are attracted towards the negative plate
Lighter ions move quicker
Mass spectrometer
Ion drift
Ion pass through a hole in the negatively charged plate
Mass spectrometer
Detection
Flight times recorded, positive ions gain an electron causing a charge and becomes neutral its self
Mass spectrometer
Data analysis
Sign from the detector is passed into a computer which generates a mass spectrum
Low resolution mass spectrometry
Measured to the nearest whole number
S-orbitals can hold ? Electrons
2
P-orbital can hold ? Electrons
6
D-orbital can hold ? Electron
10
Spin
Two electrons in the same orbital must have opposite spins
first Ionisation energy (IE)
Energy require to remove one mole of electrons from a mole of atoms in the gaseous state
Trends in ionisation energy across a period
Period 3 (Na–Ar)
Increase
Nuclear charge increses ( add a proton)
More difficult to remove an electron
Trend in ionsation energies down a group
Group 2 (Be–Ba)
Decease
Shielding
Developing ideas of the atom
1661
Robert Boyle
Some substances couldn’t be made smaller
outline how the mass spectrometer is able to separate these two species to give two peaks
- positive ion
- accelerated by the electric field
- to a constant kinetic energy
- the lightest ion registered first
What is carbon 14 used for
Carbon dating
Smoke alarms
Chemical
Medical ( can indicate cancer and other diseases)
Blip in the ionisation energy
Outer electron in Al is 3p orbital, slightly more energy is needed
New shell
Orbital
Down a group
Gets bigger
Atoms
Shielding ( another shell of electrons added each time)
1st ionisation energy across the period 4 elements
Zn — Ga (ionisation energy reduces)
It happens because different orbitals need different amounts of energy to break the repulsion between paired electrons so it is easier to remove an electron
Relative electron charge
1/1840
Arrangement of the sub-atomic particles
Protons and neutrons are in the centre of the atom in the nucleus, held together by the strong nuclear force which is stronger than the electrostatic forces
Spin
Electrons have a property called spin
Two electrons in the same orbital need have the same spin
Respected by an arrow
what is a mass spectrometer ?
it is used to identify elements
can be used to determine relative molecular mass
