Bonding. Two or more atoms join together to form a stable group. There are several types of forces (BONDS) which hold the atoms together in these groups. IONIC (ionic compounds) COVALENT (molecular compounds) METALLIC (pure elements or homogeneous mixtures)
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Two or more atoms join together to form a stable group.
There are several types of forces (BONDS) which hold the atoms together in these groups.
IONIC (ionic compounds)
COVALENT (molecular compounds)
METALLIC (pure elements or homogeneous mixtures)
WEAK INTERMOLECULAR (ie.: the forces that hold water molecules together)
High melting point
Conduct electricity when molten or dissolved in water
Low melting point
Does NOT conduct electricity when molten or dissolved in water.
An ion is an atom which has “lost” or “gained” one or more electrons, thus obtaining a “net” positive or negative charge.
Cations - ions formed when e- are lost from an atom/group of atoms
Positive Ions (+)
Usually formed from metal elements
Anions - ions formed when e- are gained by an atom/group of atoms
Negative Ions (-)
Usually formed from nonmetal elements
Covalent and ionic bonding
A Matter of Ions
Electron dot structures for selected representatives and noble-gas elements
Periodic table in which the metallic elements that exhibit a fixed ionic charge are highlighted.
Ionic Compounds are typically Crystalline in form
These elements join together because of electrostatic attractions between charged IONS. This “joining” occurs in 3D, thus, crystalline in form.
Remember, cations are usually metallic elements (or “ammonium”) and anions are usually nonmetallic elements (or MnO4-, CrO4-2, Cr2O7-2, MoO4-2).
Copper (II) oxide is black, whereas copper (I) oxide is reddish brown. Iron (II) chloride is green, whereas iron (III) chloride is bright yellow.
(a,b) Two-dimensional cross section and a three-dimensional view of sodium chloride. (c) sodium chloride crystals
Ca10(PO4)6(OH)2 + 8H+<==> 10Ca2+ + 6PO3- + 2H2O
Metal atoms LOSE valence electrons to form cations
Nonmetal atoms GAIN valence electrons to form anions
Na (1 v.e-) --> Na+ (looks like neon)
Cl (7 v.e-) --> Cl- (looks like argon)
Nomenclature of ionic compounds.
Loss of an electron from a sodium atom leaves it with one more proton than electrons, so it has a net electrical charge of +1.