CEM 141 MSU Exam 3 Questions With 100% Correct Answers.

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) Big Bang evidence - universe is expanding (red shift) Where do atoms come from? - The Big Bang What were elements formed by? - Nuclear reactions Chemical reactions - involve rearrangements of valence electrons *the element undergoing a chemical reaction does not ever change* Ionization energies are affected by - -size of an atom -size of positive charge Periodic Trends - -small atoms have higher ionization energies -they are inversely related Atomic Radius Decreases ----> Ionization energy increases - when the radius decreases, it pulls the electrons closer. decreasing the size of an atomNuclear Reactions - Fusion and Fission Fusion - two lighter nuclei combines to form a heavier nucleus (energy released) Fission - a heavier nucleus is broken a part to form lighter, more stable nuclei energy Atomic # = - # of protons Atomic mass = - what's left over Do isolated atoms or molecules have melting or boiling points? - No Do isolated atoms or molecules exist in a state (solid, liquid, gas)? - No Why do bonds form between atoms? - because valence electrons are attracted to the nuclei of other atoms Covalent Bonds - two hydrogen atoms interact and form a covalent bond What properties do metals have? - -hard -conduct electricity -shiny -react w/water -malleable Bonding in Metals - atomic orbitals combine with each other to form molecular orbitals