same number of valence electrons=behave similarly(chemical properties)
▪neon gases (neon, argon) unreactive in chemical reactions(stable)
▪Gilbert Lewis-octet rule(atoms tend to achieve electron configuration of gas)
▪atoms of metallic atoms lose electrons, atoms of nonmetal atoms lose or share electrons with another nonmetal elements to achieve a complete octet
▪to achieve octet, change electrons to ge ns2 np6 configuration
▪metals in group 1A and 2A always have charge of 1+ and 2+ (loses enough electrons to attain electron configuration of noble gas)
▪transition metals- cations vary
▪pseudo noble-gas electron configuration=18 electrons in outer level and all orbitals filled.
▪pseudo noble-gas electron configuration= silver, copper, gold, cadmium, mercury
▪name of anion ends with -ide
▪cations-> take noble electron configuration of group before, anion takes noble gas electron configuration of same group
▪Halide ions- ions produced when atoms of chlorine and other halogens gain electrons
▪ionic compounds= compounds composed of cations and anions
▪ionic compounds are electrically neutral
▪anions and cations attract one another by means of electrostatic force
▪ionic bonds= electrostatic forces that hold ions together in ionic compounds
▪chemical formula=shows the kinds and numbers of atoms in the smallest representative unit of a substance. (ex: NaCl) ▪ formula unit= lowest whole number ratio of ions in an ionic compound. (In sodium chloride, it is 1:1, one to Na+ to each Cl-)
▪Most ionic compounds are crystalline solids at room temperature
▪component ions in such crystals are arranged in repeating 3D patterns.
▪In NaCl, each sodium ion is surrounded by six chloride ions, and each chloride ions is surrounded by six sodium ions.
▪Large attractive forces of ionic compounds result in stable structures, high melting points.