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how many elements are there?
how many elements are not found on earth naturally
Main group elements
- - groups 1, 2, 13-18 are the "A" team
- - representative elements
- - main group elements
Inner transition metals
28 elements at the bottom of the periodic table
how many rows are there?
how many groups on the periodic table?
types of groups on the periodic table
- - metals
- - nonmetals
- - metalloids
- -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.
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
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 C13H18O2
- 13(12.01amu)+18(1.008amu)+2(16.00amu) = 206.27
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