Cem 141 exam 3 - Study guides, Class notes & Summaries

3-D extended continuous network (shown on tables in notes in red); continuous materials have higher boiling and melting points than discrete -️️What are continuous materials? small atoms/molecules (shoes on tables in notes in black) -️️What are discrete materials? H2: LDF He: LDF Li: metallic bonds (no LDFs in metals) move metal cores relative to one another c: covalent -️️Using the table found on lecture 25 slide 13 what kinds of interactions must be overcome in order to melt...

they have similar causes: electrostatic attraction of the electron of one atom to the nucleus of the other - ANSWER-Similarities between LDF and Covalent Bond 1. magnitude of attraction 2. how the electrons are arranged in the new species formed by the interaction - ANSWER-Differences between LDF and Covalent Bond because valence electrons are attracted to the nuclei of other atoms - ANSWER-Why do bonds form between atoms? 1. valence electrons from one atom become attracted to the nucleus...

rapid expansion of the universe -️️Big Bang how long after the Big Bang was air created? -️️few minutes how long after the Big Bang were leptons (quarks, electrons) created? -️️1 picosecond how long after the Big Bang were protons and neutrons created? -️️1 microsecond how did matter and stars begin to form? -️️in clumps

Ionization Energy - energy required to remove an electron from an atom in the gas phase Left Side Electrons - have weaker attractions to remove electrons *easier to remove electrons from the left side of the table than the right side* Does it take MORE or LESS energy to remove an electron from Li than from Na? - MORE Why? Because as we move down a group, the orbitals become larger and weaker. While going across the effective nuclear charge increases. (holds onto the electrons tighter)

Regions of space where electrons with a particular quantized energy are most likely to be found - ️️Atomic Orbitals Electrons occupy lowest level orbitals first -️️Aufbau Principle Electrons don't pair up until they have to -️️Hund's Rule Close to the nucleus -️️Core Higher in energy and far away from the nucleus -️️Valence