F331 Revision
AS Chemistry Revision-Chemistry for Life
1. Avagadro constant, 6.02 x 10²³ number of particles in 1 mole of a substance
2. Empirical formula-simplest ratio of atoms of each element in a compound
3.
4. Model of an atom
Particle
Mass on relative atomic scale
Charge
Proton
1
1+
Neutron
1
0
Electron
Very small (0.00055)
1-
5. Radioactive isotopes
Radiation
What is it?
Relative charge
How does the nucleus change?
Stopped by?
Deflection in electric field?
Alpha α
Helium nuclei
⁴₂He
+2
2 fewer protons
2 fewer neutrons
Paper or skin
Low
Beta β
Electrons
₋₁°e
-1
1 more proton
1 fewer neutron
Aluminium foil
High
Gamma ϒ
Electromagnetic radiation none No change
Lead sheet
None
6.
Half-life
i. The time taken for half a radioactive isotope/substance to decay. ii. Not affected my temperature iii. Can be used to date archaeological artefacts made from living things
Tracers
i. Radioactive isotopes whose decay is monitored ii. Can be used to aid diagnosis, followed by a Geiger counter iii. An isotope should have a half-life which is neither too short or it will decay before tracing is complete. nor too long or it will persist for too long in the body, potentially causing harm to the patient.
7. Absorption spectra
Coloured background with black lines
Lines go up
Lines get closer at higher frequency
Produced when:
i. Electrons absorb a photon (package of energy) and become excited. ii. Excited electrons move to a higher energy state- they are promoted iii. The electromagnetic radiation absorbed by each atom has a definite frequency related to the difference in energy levels by ∆E = hv
8. Emission spectra
Black background with coloured lines
Lines go down
Lines get closer at higher frequency
Produced when:
i. Electrons first absorb a photon and become excited ii. Excited electrons move up to higher energy level iii. Electrons drop back to lower energy level and emit electromagnetic radiation iv. The electromagnetic radiation emitted by an atom has a definite
1. Avagadro constant, 6.02 x 10²³ number of particles in 1 mole of a substance
2. Empirical formula-simplest ratio of atoms of each element in a compound
3.
4. Model of an atom
Particle
Mass on relative atomic scale
Charge
Proton
1
1+
Neutron
1
0
Electron
Very small (0.00055)
1-
5. Radioactive isotopes
Radiation
What is it?
Relative charge
How does the nucleus change?
Stopped by?
Deflection in electric field?
Alpha α
Helium nuclei
⁴₂He
+2
2 fewer protons
2 fewer neutrons
Paper or skin
Low
Beta β
Electrons
₋₁°e
-1
1 more proton
1 fewer neutron
Aluminium foil
High
Gamma ϒ
Electromagnetic radiation none No change
Lead sheet
None
6.
Half-life
i. The time taken for half a radioactive isotope/substance to decay. ii. Not affected my temperature iii. Can be used to date archaeological artefacts made from living things
Tracers
i. Radioactive isotopes whose decay is monitored ii. Can be used to aid diagnosis, followed by a Geiger counter iii. An isotope should have a half-life which is neither too short or it will decay before tracing is complete. nor too long or it will persist for too long in the body, potentially causing harm to the patient.
7. Absorption spectra
Coloured background with black lines
Lines go up
Lines get closer at higher frequency
Produced when:
i. Electrons absorb a photon (package of energy) and become excited. ii. Excited electrons move to a higher energy state- they are promoted iii. The electromagnetic radiation absorbed by each atom has a definite frequency related to the difference in energy levels by ∆E = hv
8. Emission spectra
Black background with coloured lines
Lines go down
Lines get closer at higher frequency
Produced when:
i. Electrons first absorb a photon and become excited ii. Excited electrons move up to higher energy level iii. Electrons drop back to lower energy level and emit electromagnetic radiation iv. The electromagnetic radiation emitted by an atom has a definite