Ch. 3.3 Flashcards
atomic number
- the number of protons
- determines type of element
- DOESN’T VARY
atomic mass units
a new unit created for measuring the mass of an atom
*amu
1 amu is how many grams?
1.7 x 10*-24 g
1 proton is how many grams?
1.673 x 10*-24 g
1 neutron is how many grams?
1.675 x 10*-24 g
1 electron is how much in amu?
0.00054 amu
atomic mass
is the mass of a single atom
*EX. 4amu + 5amu + .00216 amu = 9.00216 amu
mass number
the total number of protons and neutrons that make up the nucleus of an atom
*like an approximation
*EX. 4p + 5n + 4e = 9 amu
isotopes
is different versions of the same element
*different # of neutrons
*different masses
*elements have multiple isotopes
two ways in naming isotopes:
Hyphen notation
Nuclear symbol notation
hyphen notation
- is when the mass number is written with a hyphen after the name of the element
nuclear symbol notation
- is where the subscript indicates the mass number and the subscript indicates the atomic number
*Mass number on top
*Atomic number on bottom
average atomic mass (molar mass)
is the weighted average of the atomic masses of the naturally occurring isotopes of an element
*what is listed on periodic table
how to calculate average atomic mass:
mass # of isotopes A x % abundance
mass # of isotopes B x % abundance
mass # of isotopes C x % abundance +
——————————————
Average atomic mass
One electron ALMOST ALWAYS equals one what?
1 proton