Atom smallest unit of matter that has discrete and observable chemical properties building blocks of matter smallest identifiable unit of an element Submicroscopic particles magnify 100 million times Scanning Tunneling Microscope allows you to see atoms at the surface needle that is 10 9 meters from surface causes vibrations Atoms are divisible and consist of subatomic particles electrons neutrons and protons Electron e 1 charge Proton p 1 charge Neutron n0 0 charge Electrically neutral when protons electrons An atom of a specific element has a characteristic number of protons but can differ in the number of electrons and neutrons Metals conduct heat electricity and are solid Non metal poor conductors solid liquid and gasses Metalloids exhibit properties of both metals and non metals Vertical columns Groups Horizontal rows Periods Group 1 1A Alkali Metals Very Reactive Group 2 2A Alkaline earth metals Reactive Solids Group 18 8A Noble gases Unreactive monatomic gases Group 17 7A Halogens X2 Very reactive nonmetals Formulas of the gaseous element that exist as diatomic gases H2 N2 O2 F2 Cl2 Formulas of the gaseous element that exist as monatomic gases He Ne Ar Xr Xe Rn metals tend to take part in chemical reactions by LOSING electrons Form positive ions called cations with the same number of electrons as Atoms of groups 1 2 3 the nearest noble gas Atoms in groups 5 7 Nonmetals tend to take part in chemical reactions by gaining electrons Form negative ions called anions with the same number of electrons as the nearest noble gas Orbitals volume of space where there is a possibility of finding an electron Need to know the S block D block P block E block The orbital that corresponds to that wave function is specified using three interrelated quantum numbers The principal quantum number n relates the size and energy of the orbital n cannot be zero An increase in n means orbital becomes larger and higher in energy electron is further from the nucleus The angular quantum number l describes the shape of the orbital o L has integral values from 0 to n 1 for each value of n o When l 0 we are speaking of an s orbital spherical shape o When l 1 we are talking about p orbital dumbbell shape o When l 2 we are speaking of a d orbital cloverleaf shape 5 kinds of D orbitals For n 1 the allowed value of l is 0 and so the orbital is 1s For n 2 the allowed value of l are 0 and 1 so the orbitals are 2s and 2p N and L cannot be equal L cannot be more than N N written first then L decided based on letter Magnetic Quantum number ML provides the maximum number of orbitals for the different values of L o Ml has values between l and l including the number zero o Ml is related to the orientation of the orbitals in space relative to the other orbitals in the atom When l 1 Ml 1 0 and 1 A fourth quantum number the spin quantum number Ms specifies the spin of an electron on its own axis o Ms can only have values of and o The spin of an electron on its own axis can be clockwise or counterclockwise PAULI EXCLUSION PRINCIPLE No two electrons in an atom can have the same four quantum numbers If two electrons in an atom have the same values of n l and ml they must have different values of ms HUNDS RULE Electrons do not pair in an orbital until all the other orbitals in the subshell have been occupied by a single electron be single before getting married Write full electron configuration of Ca 20e s p g d f 1 2 3 4 5 2 3 4 5 3 4 5 4 5 5 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 4 s 2 Shorthand electron configuration Hg 80e Xe 6 s 2 4 f 14 5 d 10 54 Exceptions in electron configurations Chromium The electron configuration of chromium is not as predicted using Hund s Rule Copper An excited atom or ion contains the same number of electrons as in the ground state but one or more electrons have gained sufficient energy to move to higher energy orbitals First in First out rule For transition metals ns electrons are added before n 1 d electrons to form the atom but ns electrons are lost before n 1 d electrons to form the ion