Parts of the Atom

Relative electric charge Subatomic Particles particle symbols Relative electric charge Mass number Relative mass (amu) Actual mass (kg) electron proton neutron -1 e- 0.0055 9.1 x 10-31 p+ 1.007 +1 1 1.7 x 10-27 n0 1 1.008 1.7 x 10-27 Mass number of an atom with: The electron doesn’t contribute any significant mass to the atom. 1 proton = 1 (1.007amu) 1 electron = 0 (0.0055 amu) 1 neutron = 1 (1.008 amu) 2 amu

Atomic number is the number of protons Mass number is the number of protons + neutrons. An atom with 6 protons and 7 neutrons has an atomic number of 6 and a mass number of 13. This atom would be carbon because carbon’s atomic number is 6.

Isotopes Isotopes are atoms of the same element with different masses. Not all atoms of an element are the same. Not all atoms of hydrogen are the same. There exists 3 isotopes (types) of hydrogen. Substitute the word variety (or flavors).

H C Isotopes of Hydrogen Isotope Nuclear Symbol Number of protons Number of electrons Number of neutrons hydrogen-1 hydrogen-2 hydrogen-3 1 H 1 1 2 1 H 1 1 1 3 1 H 1 1 2 mass number= protons + neutrons protons + neutrons 1 p + 2 n H 3 1 6 p + 7n C 13 6 atomic number= protons 1 p protons 6 p

Isotopes of Hydrogen Isotope Nuclear Symbol Number of protons Number of neutrons Mass number hydrogen-1 hydrogen-2 hydrogen-3 1 H 1 1 2 1 H 1 1 2 3 1 H 1 2 3 Mass number is the number of protons + neutrons.

Ions Cl + e- a Cl-1 S + 2e- a S-2 Na a Na+1 + e- Ions (not to be confused with isotope) Ion is an atom that has either lost or gained electrons and therefore has a charge. (not neutral) Cl + e- a Cl-1 Ions S + 2e- a S-2 Na a Na+1 + e-

Symbol Atomic number Mass number # of protons # of neutrons # of electrons charge O 9 K 39 19 40 F-1 -1 8 17 8 8 19 19 20 19 19 21 19 9 9 10 10 Use the periodic table to find atomic number. Atomic number = # of protons. Mass number = # of protons + neutrons Since the charge is zero, # of protons = # of electrons