CHEM 110 Lecture Notes - Lecture 8: Hydrogen Storage, Lattice Energy, Electron Configuration
15 Jun 2018
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Descriptive Main Chemistry
CHEM 110: DESCRIPTIVE MAIN GROUP CHEMISTRY
Hydrides (hydrides when they’re part of a molecule):
- salt-hydrides (traditional salts LiH, metal with H gas, CaH2, you make H- type of
salts because the metal is positive, oxidation -1)
- covalent hydrides (molecules with covalent bonds to hydrogen, like h20,
bonded to more electronegative, oxidation number 1, H+, neutral or acidic)
- metallic hydride (transition metals, no discrete molecules, just hydrogen
molecules into the certain spaces, do not make bonds, mixtures with solid + gas,
gas is trapped, hydrogen storage → fuel of the future)
Exploring the rest of Periodic Table:
Group 1 Alkali Metals:
Atomic Properties:
- large size/low valence
- lowest IE & electronegativity in period
- size increases down a group
- IE/EN decreases down group
- prefers to form +1 cations*
Physical Properties: electron configuration affects the following →
- weak metallic attraction as you go down which affects:
- soft as you go down, low mp/bp, very conductive
- large size: mass ratio – low density
- mp/bp decreases down the group
- density increases down the group
Reactivity:
1. Mix Alkalis with Halogens → makes a salt (high lattice energy)
2. Alkalis + Hydrogen → hydrides
3. Alkalis + H20 → H2 gas, OH- + Alkali Cation (video rxn, mythbusters)
4. Alkali + O2 → AlkaliO the metal tarnishes, forms oxides
Group 2:
Atomic Properties:
- Bonding is stronger, still large size/low valence except smaller than Gr.1
elements
- Second lowest IE and EN in period
- Prefers for 2+ cations
- The other facts are the same as Gr.1
Physical Properties:
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Document Summary
Hydrides (hydrides when they"re part of a molecule): Salt-hydrides (traditional salts lih, metal with h gas, cah2, you make h- type of salts because the metal is positive, oxidation -1) Covalent hydrides (molecules with covalent bonds to hydrogen, like h20, bonded to more electronegative, oxidation number 1, h+, neutral or acidic) Metallic hydride (transition metals, no discrete molecules, just hydrogen molecules into the certain spaces, do not make bonds, mixtures with solid + gas, gas is trapped, hydrogen storage fuel of the future) Atomic properties: large size/low valence lowest ie & electronegativity in period. Physical properties: electron configuration affects the following . Weak metallic attraction as you go down which affects: Soft as you go down, low mp/bp, very conductive large size: mass ratio low density. Bonding is stronger, still large size/low valence except smaller than gr. 1 elements. Second lowest ie and en in period. The other facts are the same as gr. 1.
