Atomic structure & the periodic table
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- Created by: Shannon
- Created on: 04-03-14 19:04
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- Atomic structure & the periodic table
- Ionisation energy
- Defintion
- "The amount of energy needed to remove an electron from a mole of gaseous atoms"
- General trend
- Decreases down the group
- Increase in atomic radii leads to greater shielding.
- Despite the addition of protons
- Increase in atomic radii leads to greater shielding.
- Increase across a period
- Addition of a proton causes a greater force of attraction between nucleus and outer electrons.
- Decreases down the group
- Endothermic processes
- Defintion
- The Bohr model
- It explains...
- Why noble gases are generally unreactive
- Complete outer shells gives stability.
- The charge on ions.
- Based on the number of electrons in the outer shell.
- Reactivity down a group.
- Reactivity increases
- Shells provide shielding to the outer electrons, so there is less attraction to the nucleus.
- Reactivity increases
- Why noble gases are generally unreactive
- It is limited because of the evidence for the quantum shell model
- The blips in first ionisation energy across a period provide support for the quantum shell model
- Successive ionisation energies support the quantum shell model, and tell us which group the element belongs
- It explains...
- Sub-shells
- Have different shapes: s, p or d
- s = 2 electrons
- d = 10 electrons
- p = 6 electrons
- Have different shapes: s, p or d
- Electronic configuration
- Electrons fill shells singularly before beginning to pair up
- Repulsion
- Show the number of electrons and their arrangement.
- This can be isoelectronic
- Show the occupied energy of electrons in different orbitals.
- Electrons fill shells singularly before beginning to pair up
- Electron spin
- Two electrons in the same orbital cannot have the same spin.
- In an orbital, 1 electron must have an up spin, and the other a down spin.
- Two electrons in the same orbital cannot have the same spin.
- Mass spectrometry
- Basic principles
- Deduce the isotopic composition of a sample of an element
- deduce the relative atomic mass of an element
- Measure the relative molecular mass of a compound
- 5 steps
- Deflection
- Ions passed through a magnetic field. Deflected according to mass. Higher = less deflection
- Vaporisation
- Acceleration
- Ions accelerated in an electric field
- Detection
- Ions focused on a detector plate
- Deflection
- Uses
- Space exploration - analyse samples of plasma
- Drug testing - T:E ratio in urine
- Basic principles
- Electron density maps
- Shows the shapes of the area of space where an electron is likely to be
- Melting temperatures in periods 2 & 3
- Dependent on on structure
- Li, Mg, Al = high due to metallic structure
- C & Si = high due to giant macromolecular structures
- Non metals = low melting points as simple structures
- Dependent on on structure
- Ionisation energy
- p = 6 electrons
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