In ancient Greece, around 384-322 BC, philosophers such as Aristotle theorised that everything was composed of just four elements: Earth, Water, Air and Fire. However we now realise that these are just states of matter: solid, liquid and gas. Antoine-Laurent de Lavoisier In 1798, Antoine-Laurent de Lavoisier and his wife together produced what is now considered … Continue reading
Monthly Archives: November 2012
Lesson 10 – Intermolecular Forces
Intermolecular forces act between molecules. They are a lot weaker than ionic and covalent bonds and are caused by small dipoles in different molecules. There are three types of intermolecular force: Hydrogen Bond Permanent Dipole-Dipole Forces Van der Waals’ Forces Permanent Dipole-Dipole Interactions The permanent dipole of one polar molecule attracts the permanent dipole of … Continue reading
Linus Pauling
Linus Pauling was a profound American chemist. He was one of the founders of such fields as Quantum Chemistry and Molecular Biology. Pauling went to a public elementary school in Portland, Oregon before in 1917 he entered the Oregon State College, obtaining a degree in chemical engineering by 1922. Pauling was also offered the role of a full-time teacher of … Continue reading
Lesson 9 – Covalent Bonds
Covalent donds happen between two non-metals. In convalent bonds a pair of electrons is shared between two atoms.The negatively charged electrons attract the positively charged electrons. A covalent bond is directional and acts only between the two atoms involved. Intermolecular bonds are very weak. Dative Covalent Bonds In dative covalent bonds only one of the … Continue reading
Lesson 8 – Electronic Structure
Ionisation Energy – The measure of the energy required to remove 1 e– from every atom in 1 mole of gaseous atoms to form one mole of monopositive ions X(g) –> X+ + e– As electrons get closer to the nucleus the energy needed to remove them becomes greater. Orbitals – an orbital is an … Continue reading
Chemistry. 