This preview shows pages 1–4. Sign up to view the full content.
SCIE1110: Great Ideas in Science Spring 2016 Chemistry Module: Prof. Ian D. WilliamsRm 6005 CYT [email protected]Lecture 3. Chemical Bonding
has intentionally blurred sections.
Sign up to view the full version.
Lecture 2 Periodic Table: Summary By end of 18thcentury concept of elements well established thanks to Lavoisier, who had disproved Phlogiston Theory. Daltonproposed new Atomic Theoryby 1808. Though most of his ideas not entirely correct, they were a useful workingmodelfor chemistry of elements and their compounds. In chemical reactions atoms are neither created or destroyed, but change in their combinations with each other. In 1807 Davy made breakthrough in isolating many electropositive metal elements, using electrochemistryto produce Potassium (potash), Sodium (Soda), Magnesium and Calcium. As more elements discovered scientists speculated about what made them different and questioned how many there could be. Prouttheorized that all elements were multiples of hydrogen, the simplest atom. He was close –number ofprotonsdo determine element type Swede Berzeliustook Davy‘s work further & with reactive potassium could isolate others, such as silicon, from their salts. He introduced modern chemical symbolsfor the elements and a simple integer notation for chemical formulas (e.g. H2O for water). Berzelius‘ greatest contribution was the firstaccuratedeterminations of relative atomic weights. Atoms of an element are not identical since they can have different isotopes, which would later explain unusual fractional masses, such as for chlorine. C3.2 SCIE 1110 Spring 2016