IONS ANDISOTOPES
CHARACTERISTICS OFIONS
Ions are particles with a +/- charge
All ions begin as neutral atoms
Atoms that have lost electrons are called CATIONS
Atoms that have gained electrons are called ANIONS
All electrons that are lost are gained are VALENCE Electrons
Valence electrons are outer shell electrons that are looselyheld by the atom
All atoms want to have 8 valence electrons so that they canbe stable
Losing and gaining electrons accomplishes this duringreactions
POSITIVE IONS(CATIONS)
Positive ions have lost 1 or more (up to 3) valence electrons
The number of electrons is less than the number of protonsso the ion has a net positive charge
EX: Na+1 Ion…11 Protons and 10 Electrons
11-10 = +1 net charge
Positive ions are smaller than the atom they came frombecause they lose an entire energy level when they releasean electron
Metals ALWAYS form positive ions
NEGATIVE IONS(ANIONS)
Negative ions are formed when an atom gains one or moreelectrons (up to 3) from another atom
The number of electrons is greater in an negative ion than inthe neutral atom
Net charge is negative
Ex: O2- ion 8 protons and 10 electrons
8 - 10 = -2 electrons left
Negative ions are LARGER than the atom they came frombecause the extra electrons occupy more space
NON-METALS FORM NEGATIVE IONS
ISOTOPES
Same element (same number of protons) different number ofneutrons
The difference in neutrons creates a sample with a differentmass
All elements have at least 1 isotope
This is why on the periodic table we use a weighted averageatomic mass to represent the mass of the element
If all isotopes are not known, the mass of the element is inparenthesis (259).
