Warm-up When looking at an atom, how might we determine what element that atom is from?

The ugly parts to the atom SUBATOMIC PARTICLES The ugly parts to the atom

Subatomic particles Atoms consist of 3 types of subatomic particles Protons Neutrons Electrons

Protons Protons have a positive charge Found in the center of the atom called the nucleus Usually represented with the symbol “p+” The number of protons determine which element a particular atom is

Neutrons Neutrons have no charge or a neutral charge Found in the nucleus Number of neutrons of a particular element may vary, but b/c they are neutral there is no change in charge When the number of neutrons vary for a particular element we call it an isotope

Electrons Electrons have a negative charge They reside in the electron cloud away from the nucleus They are smaller than both the neutron and proton Electrons determine how an element will react

Atomic Number Games The # of protons = the number of electrons The # of protons = atomic number The # of protons + # neutrons = atomic mass Atomic mass – atomic # = # of neutrons NOTE: IF THE # OF PROTONS CHANGE, SO MUST THE ELEMENT

Relative Size of Particles Protons and Neutrons are about the same size in terms of mass An electron is about 1/1836 the size of a proton This means that electrons are VERY small in comparison to protons and electrons

Isotopes An isotope of an element is an element that has the same atomic number but its atomic mass may vary This variation occurs because the number of neutrons can change without affecting the charge of the atom Remember ALL ELEMENTS HAVE AN OVERALL CHARGE OF ZERO