Subatomic Particles The atom is composed of three main subatomic particles: _____________, _______________, and, _________________________
Table 1. Mass, charge, and location of the three subatomic particles.
Particle
Label the atom
Charge
Mass (atomic mass units or amu)
Electron
Proton
Location
Neutron
Nucleus
Each element is defined by it's number of protons. This can be seen in the atomic number.
Atomic Number:
­ Elements are organized in the periodic table according to their atomic number
­ the atomic number of an element ________ it's number of protons. How many protons do the following elements have in their atoms?
Mg: ________
silicon: ___________
Fe: ___________
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Atomic Mass:
­ This is the average _______ of the atom
Which two subatomic particles have the most mass?
Atomic mass = # of _____________ + # of ___________ Also to find the number of neutrons, rearrange to get
# of neutrons = ___________________ ­ ________________
­ The atomic mass is not always a whole number, as it is an average of all of the atom's naturally occurring isotopes.
­ The term isotope refers to different forms of an element that have the same number of protons but different number of neutrons. Ex: 13 C or carbon­13
To find number of electrons
We will be dealing with atoms that are neutral. Therefore there must be the ____________ number of protons as electrons.
number of electrons = number of protons = atomic number
For each of the following, find the number of protons (p),
electrons (e), and neutrons (n).
Na: p =
e=
n=
copper: p =
e=
n=
S :p=
e=
n=
aluminum: p =
e=
n=
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