Masses of Atoms. Element ~ smallest particle that is unique from all others

Masses of Atoms

Element ~ smallest particle that is unique from all others


Symbol ~ unique letter to represent element



Atomic Number ~ number of protons in the atom of an element




Carbon - 12 (6 protons, 6 neutrons)





Atomic Mass ~ number of neutrons AND number of protons

Isotope ~ atoms of the same element, with different numbers of neutrons








SAME ELEMENT, DIFFERENT NEUTRON NUMBERS






Atomic Mass Unit ~ 1/12th of the mass of one carbon-12 atom







The periodic table shows the atomc mass of Nickel as 58.693. How can there be a decimal point, if the mass is whole numbers of protons and neutrons?







The periodic table shows the atomc mass of Nickel as 58.693. How can there be a decimal point, if the mass is whole numbers of protons and neutrons?

Example, with boron.

Facts: Boron has an accepted amu of 10.811

80% of Boron in nature have 5 protons, 6 neutrons ~ 11 amu

20% of Boron in nature have 5 protons, 5 neutrons ~ 10 amu

(.8 • 11 amu) + (.2 • 10 amu) = 8.8 amu + 2 amu = 10.8 amu

There are a few extra isotopes out there that we did not include.

Nickel, in nature, has 8 (pretty) stable isotopes. Each has (of course) 28 protons.

Percent NumberNumber Atomic inof of mass Isotope nature

protons neutrons units

Ni-58 69% 28 30 58

Ni-60 27% 28 32 60

Ni-62 4% 28 34 62

What, given this information, is the approximate atomic mass of Nickel?

Nickel, in nature, has 8 (pretty) stable isotopes. Each has (of course) 28 protons.

Percent NumberNumber Atomic inof of mass Isotope nature

protons neutrons units

Ni-58 69% 28 30 58

Ni-60 27% 28 32 60

Ni-62 4% 28 34 62

(.69 • 30) + (.27 • 32) + (.4 • 34) = 58.7 amu

Documents

Masses of Atoms. Element ~ smallest particle that is unique from all others