Periodice table and energy
- Created by: GummyBear
- Created on: 13-03-17 17:48
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- PERIODIC TABLE AND ENERGY
- PERIODICITY - the trend in physical and chemical properties repeated across each period in the periodic table
- As atomic no increases, atomic radius decreases - shielding is constant, no. of proton increases and no. of electrons, nuclear charge is greater so more attraction
- Giant metallic, giant covalent, simple covalent
- GM= positive metal ions and sea of delocalised electrons, positive and negative charges increase
- GC= electrons attracted by two nuclei, large no's of strong covalent bonds
- SC= weak intermolecular forces and very low MP's and BP's
- FIRST IONIATION ENERGY - the energy required to remove the outermost electron from every atom in 1 mole of gaseous atoms
- X(g) = X+(g) + e-
- Increases across a period - more protons, increased nuclear charge, more electrons, shielding is constant, increased electrostatic attraction
- SUCCESIVE IONISATION ENERGY - the energy required to remove each electron in turn from the outermost shell
- Large increase in SIE = new shell
- ELECTRONICONFIGURATION
- Each shell holds 2n (squared) - 1=2, 2=8, 3=18, 4=32
- Electrons occupy orbitals - regions of space outside the nucleus where the electrons are most likely to be found
- Must have opposite spin
- ORBITALS
- Hold a max of 2 electrons
- S = spherical, 2 electrons in subshell
- P = 3D dumbbell shape, 6 electrons in subshell
- D = 10 electrons in subshell, F= 14
- 1s, 2s,2p,3s,3p, 4s, 3d, 4p, 4d,4f
- Noble gas short hand for elements in the period after argon
- DEVELOPMENT
- 340 BC Aristotle - five elements - air, earth, water, fire and aether (wind) - all matter made of these elements
- Antoine Lavoisier - named elements C, H and Oxygen, water = H2O, 'Law of conservation of mass'
- Berzelius - concepts of ion and ionic compounds, 1826 table of atomic weights, 1811 classical system of chemical symbols
- Dobereiner - 1817 law of triads (3 elements where appearance and reactions were similar), importance of atomic weights
- Chancourtois - 1862 3D arrangement of the elements, atomic weights on telluric screw
- John Newlands - law of octaves, no gp 8, no gaps and two elements in a box
- Mendeleev - arranged elements in order of atomic mass, gaps, 1890's =noble gases discovered
- Henry Moseley - method to measure atomic number
- Glenn Seaborg - discovered radioactive elements
- PERIODICITY - the trend in physical and chemical properties repeated across each period in the periodic table
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