ELEMENTS, IONS AND ISOTOPES UNIT #2 THE ATOM

The Subatomic Particles Protons – positive charge (p+) Neutrons – neutral charge (n0) Electrons – negative charge (e-) Protons and neutrons are found in the nucleus Electrons are found in the electron cloud

Atomic Number and Atomic Mass Atomic number is the number of protons in the atom Atomic mass is the number of protons + neutrons The number of protons an atom has determines which element that atom is

Practice Identify the atomic number, the atomic mass and the element of the atoms below:

Isotopes Atoms which have the same number of protons (have the same atomic number) but are different in the number of neutrons (have different atomic masses)

Ions Atoms which are charged – have a different number of protons and electrons

Using Symbols to Represent Isotopes

Practice Isotope Atomic Number Mass Number Protons Neutrons Electrons 32 16 18 50 69 46 37 48 36

Important Side Note When chemists are discussing ions, they typically will not use the isotopic notation Instead, the will just write the element symbol and the charge Also: when the charge is +1 or -1, write just – or +