unit 6: ionic and covalent compounds

chemical bonds

a mututal attraction between the valence electrons of one atom and the protons in the nucleus of another atom

ionic bonding

• b/w metals and nonmetals

• valence electrons are COMPLETELY transferred from the metal atom to the nonmetal atom

• b/w atoms in ionic bonding, there is electrostatic attraction

• there is a pos sphere of charge and a neg sphere of charge

covalent bonding

• formed b/w nonmetals and nonmetals

• valence electrons are shared in pairs between bonded atoms

non polar covalent

• occurs between two identical atoms

• even distribution of the bonding electron cloud

polar covalent

• electrons are shared but not equally

• separation of charge -

  • the more electronegative element = a partial negative charge

  • the less electronegative element = a partial positive charge

• dipole arrow = shows separation of charge in a molecule

  • positive TO negative

metallic bonding

• valence electrons are shared among all atoms of the substance

• occurs when metals are bonded to themselves or mixed with other metals (ALLOYS)

alloys

mixture of a metal with other metals or nonmetals

brass

copper and zinc

bronze

copper and tin

carbon steel

iron and carbon

solder

lead and antiomny

stainless steel

iron chromium nickel

EN formulas

• ionic: EN >= 1.7

• polar covalent: 1.6 >= EN >= 0.5

• nonpolar covalent: EN < 0.5

electronegativity

• defined as the ability of an atom in a covalent bond to attract trhe bonding electron cloud to itself

• trend: increases across periods, decreases down groups