Atomic number = the number of protons (+) in an atom
It is the number at the top of an elements square
Example: Tungsten (W) has an atomic number of 74
Atomic mass = the number of protons and neutrons in an atom
The # of neutrons can be calculated by subtracting the atomic mass and atomic number
Example: Silver (Ag): 108 - 47 = 61 neutrons
The periodic table reflects neutral atoms & the # protons = the # of electrons to present a neutral charge.
Example: Phosphorus has an atomic number of 15, which means in a neutral atom is has 15 protons and 15 electrons.
Isotopes are atoms that have the same number of protons (atomic number) and identity, but a different number of neutrons (atomic mass).
Example: carbon-12 and carbon-13 are isotopes of one another because they both have the same atomic number but a different number of neutrons
Ions can occur when atoms interact. Cations are formed when metals lose electrons. Anions are formed when (typically) nonmetals gain electrons.
Example: Na can lose an electron & become the cation Na+
Example: Cl can gain an electron & become the anion Cl-
Ionic compounds have a metal and nonmetal bonded together.
Groups 1 and 2 are metals
Groups 14 to 18 are nonmetals
Example: NaCl
Covalent compounds have a nonmetal bonded to another nonmetal
Examples: CO2
