Week 1 (Energy and length scales. Atoms composition) Flashcards
Whats matter?
Anything that has mass and takes up space (volume)
Categories of Matter
Pure substances (only one type substance)
Mixture (more than one type substance)
Pure Substances (2)
Element (one type atoms)
Compound (more one type atom)
Mixture (2)
Homogeneous (uniform composition)
Heterogeneous (irregular composition)
Define an Atom
Smallest possible unit into which matter can be divided, while still maintaining its properties.
Atomic Strucutre:
what are the two basic components in every atom
Electron cloud
Nucleus
What are the 3 subatomic particles:
Proton
Neutron
Electron
Protons (6)
- Positively charged particles
- Help make up the nucleus of the atom
- Help identify the atom (~ an atom’s DNA)
- Equal to the atomic number of the atom
- Contribute to the atomic mass
- Equal to the number of electrons
Neutrons (3)
- Neutral particles; have no
electric charge - Help make up the nucleus of
the atom - Contribute to the atomic mass
What do quarks make up?
Particles that make up protons and neutrons
Charge of an up quark:
+2/3
Charge of a down quark:
-1/3
Electrons (7)
- Negatively charged particles
- Found outside the nucleus of the atom, in the
electron orbits/levels; each orbit/level can
hold a maximum number of electrons
(more on this next week) - Move rapidly mainly around the nucleus ~ an
electron cloud - Mass is insignificant when compared to
protons and neutrons - Equal to the number of protons
- Involved in the formation of chemical bonds
- Most important for chemistry
Sub-Atomic Particles
Wieght Comparison
Neutron = 1.6749286 x10-27 kg
Proton = 1.6726231 x10-27 kg
Electron = 9.1093897 x10-31 k
Length comparison (metres):
Atom = 10^-10
Nucleus = 10^-14
Proton or Neutron = 10^-15
Electron = 10^-18
Wavelength is inversely proportional to …
energy of wave
Frequency is directly proportional to …
energy of wave
Why is it the W=wavelength light using has to be similar to that of the part matter you’re trying to probe?
Each region EM spectrum of light, interacts with matter different ways.
UV photons and upwards are …
- ionising
- dangerous
- excite core electrons
Forces in atoms:
- Gravitational (only one, not described by standard model)
- Electromagnetic
- Strong Nuclear Force
- Weak Nuclear Force
Gravitational Force:
force attraction of objects due to their masses (amount depends on their masses and distance , not significant force, holding atoms).
Electromagnetic Force:
resulting from repulsion like charges, attraction opposite. It holds electrons around nucleus.
Strong Nuclear Force:
Holds atomic nucleus together.
Counteracts the electromagnetic force (protons repelling).
Weak Nuclear Force:
Plays key role in possible changes, sub-atomic particles.
Responsible, radioactive decay (process, were nucleus of radioactive unstable atom releases nuclear radiation). Original particle changes, something new.
We can’t ask where is the electron right now, ask in this particular part of space if I look for the electron what’s the likelihood I’ll find it there, electrons can be placed (different probabilities)
What equation do we use?
Schrödingers equation, calc the electrons probability wave, can predict were percentages of where the electron will lie with high certainty.
Everything in the universe (atoms / matter) runs on probability and not certainty. Determined by chance
