1. Atomic Structure Flashcards
What is a nucleon?
Another word for protons and neutrons, since both are found in the nucleus
What is a proton’s mass (kg) and charge (C)?
1.673 x 10^-27 kg, +1.602 x 10^-19 C
What is a neutron’s mass (kg) and charge (C)?
1.675 x 10^-27 kg, 0 C
What is an electron’s mass (kg) and charge (C)?
0.911 x 10^-30 kg, -1.602 x 10^-19 C
What are the relative masses and charges of protons, neutrons and electrons?
Proton: 1, +1
Neutron: 1, 0
Electron: 1/1840, -1
How are protons and electrons held together?
By strong electrostatic forces which are not as strong as the nucleus force that holds together protons and neutrons in the nucleus
Why is a strong nuclear force in the nucleus necessary?
To stop the protons repelling one another
What is the plum pudding model?
A sphere of positive matter (protons) containing negatively charged electrons arranged in circular arrays
What are isotopes?
Atoms of the same element with different numbers of neutrons
What are carbon’s isotopes and what is their abundance?
Carbon-12: 98.89%
Carbon-13: 1.11%
Carbon-14: Trace
What is half-life?
The rate at which a radioactive isotope decays
How can we use knowledge of an isotope’s half-life in carbon dating?
- Carbon-14 has a half-life of 5730 years
- It can be used to date organic matter up to 60,000 years old, but is more effective up to 2,000
- Organic matter always gives out and takes in carbon when living so levels of C-14 stay the same
- When is dies, the C-14 deigns to decay
- So if the matter had 1/2 the level of radioactivity expected in living organic matter, it would be 5730 years old
How does the mass spectrometer detect m/z values?
Read in folder
How many orbitals does each sub-level have?
s = 2 p = 6 d = 10
What are the rules for electron pairing in orbitals?
- Electrons will only pair up in a sub-level when all other orbitals are full
- The paired electrons must have opposite spin
- An electron is a cloud of negative charge which fills a volume called its orbital
What are the exceptions to the rules of electron arrangement?
- The 4s sublevel has a lower energy level than 3d, so is filled first
- When full, the 4s sublevel has a higher energy level than 3d, so electrons are always removed from here first
- At chromium, one electron is taken out of the 4s sub-level before it is replaced at Mg
- This happens again at copper
What is first ionisation energy?
Enthalpy change when one mole of electrons is taken from one mole of gaseous atoms resulting in the formation of one mole of unipositive ions
X (g) –> X+ (g) + e-
What is second ionisation energy?
Enthalpy change when ne mole of electrons is removed from unipositive ions in a gaseous state producing one mole of gaseous ions with a charge of +2
X+ (g) –> X2+ (g) + e-
What affects required ionisation energy?
- Nuclear charge
- Shielding
- Atomic radius
