# Chem1090 Test#1

 how many elements are there? 118 how many elements are not found on earth naturally 28 Main group elements - groups 1, 2, 13-18 are the "A" team- representative elements- main group elements Transition Metals - groups 3-12- "B" group Inner transition metals 28 elements at the bottom of the periodic table how many rows are there? 7 how many groups on the periodic table? 18 types of groups on the periodic table - metals- nonmetals- metalloids Temperature conversions F=C(1.8)+32C=(F-32)/1.8K=C+273.15 Si Units -7 total units- we typically only use 5 what is the atomic number? the number of the element itself what is the mass number? the atomic mass ex. He (Helium) atomic mass is 4.003 what are isotopes? atoms that have the same atomic number but different mass number protons, neutrons, and electrons Subtract the number of protons from the isotope number to get the number of neutrons. Atomic mss the mass of an atom (AMU) Example - Isotopes 12C and 13C with AMU's 12.00000 and 13.003355 and natural abundance % of 98.93 and 1.07 Average mass (C)= (0.9893)(12.00000amu)+(0.0107)(13.003355amu) = 12.01 amu atomic weight represents the average mass of the naturally occurring mixture of isotopes percent composition by mass -% mass of an element= n(atomic mass of element)/molecular or formula mass of compound- the multiply answer by 100% example: molecular mass of ibuprofen C13H18O213(12.01amu)+18(1.008amu)+2(16.00amu) = 206.27 Density D=M/V or D=g/ml Authornaegelekd ID176288 Card SetChem1090 Test#1 DescriptionTest #1 Updated2012-10-08T19:39:05Z Show Answers