CEM 141 MSU Exam 3 Questions & Answers Solved 100% Correct!!

Ionization Energy - Answer-energy required to remove an electron from an atom in the gas phase Left Side Electrons - Answer-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? - Answer-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) Big Bang evidence - Answer-universe is expanding (red shift) Where do atoms come from? - Answer-The Big Bang What were elements formed by? - Answer-Nuclear reactions Chemical reactions - Answer-involve rearrangements of valence electrons *the element undergoing a chemical reaction does not ever change* Ionization energies are affected by - Answer--size of an atom -size of positive charge Periodic Trends - Answer--small atoms have higher ionization energies -they are inversely related Atomic Radius Decreases ----> Ionization energy increases - Answer-when the radius decreases, it pulls the electrons closer. decreasing the size of an atomNuclear Reactions - Answer-Fusion and Fission Fusion - Answer-two lighter nuclei combines to form a heavier nucleus (energy released) Fission - Answer-a heavier nucleus is broken a part to form lighter, more stable nuclei energy Atomic # = - Answer-# of protons Atomic mass = - Answer-what's left over Do isolated atoms or molecules have melting or boiling points? - Answer-No Do isolated atoms or molecules exist in a state (solid, liquid, gas)? - Answer-No Why do bonds form between atoms? - Answer-because valence electrons are attracted to the nuclei of other atoms Covalent Bonds - Answer-two hydrogen atoms interact and form a covalent bond What properties do metals have? - Answer--hard -conduct electricity -shiny -react w/water -malleable Bonding in Metals - Answer-atomic orbitals combine with each other to form molecular orbitals Covalent bonds hold atoms together within.. - Answer-moleculesMolecular interactions hold atoms together between... - Answer-molecules T/F: Covalent bonds are stronger - Answer-True Why are metals shiny? - Answer-photons of wavelengths are absorbed and then re-emitted Changes of state (solid --> liquid ---> gas) - Answer-REQUIRES energy Changes of state (gas --> liquid --> solid) - Answer-RELEASES energy Where does the energy come from? - Answer-The surroundings Where are the attractions coming from? - Answer-Between the molecules Ionic Bonds - - Answer-are between a metal and non-metal Bonding in Diamond - Answer-each carbon atom is bonded to make more carbon atoms Valence Bond - Answer-atomic orbitals overlap to form a bond Bonding in Graphite - Answer-one s and two p orbitals hybridize to give three Sp2 orbitals Heterogeneous Compounds - Answer-bonding in carbon compound bonds to C,H,O,N,S,P Lewis Structure - Answer-1. group number = how many valence electrons 2. for cations = (+) remove electrons 3. for anions = (-) add electrons 4. use 2 electrons for each atomFormal Charge: - Answer-Valence electrons on free atom - #bonds to atoms - non bonded electrons = Formal charge Example: OH- 6 from oxygen +1 from hydrogen +1because its minus 1 ion = 8 valence electrons Electronegativity - Answer-ability of an element to attract electrons to another electron Electronegativity ... - Answer-increases across the table decreases down the table Polar Bonds - Answer-when two atoms of different eleectronegativities bond, the electrons are not shared equally - results in dipole Which Bonds are Polar? - Answer-H-F H-O CH3F H20