7.2

1. 7.2 Ionic and Covalent Bonds

2. Ionic Bonds – Loss and Gain • Elements can become stable by gaining or loosing an electron • Positive and Negative Ions • Loss or gain of an electron changes the charge of the atom • Ion – an atom that is no longer neutral • Ionic bond – chemical bond created by the gaining or loosing of electrons • Compound – a pure substance that contains two or more elements

3. Ionic Salts • Hard crystalline compound with positive ions of metal atoms and negative ions of nonmetal atoms • Will conduct electricity in solutions because charged particles can move • More Gains and Losses • Some atoms can give more than one electron • Magnesium

5. Covalent Bonds – A Matter of Sharing • The Covalent Bond • Atoms share electrons to become more stable • Covalent Bond – chemical bond created by sharing electrons • Electrons are attracted to the nuclei of two atoms at the same time • Move between the two outer energy levels so that each atom has a full outer energy level some of the time

6. Molecule – neutral particle formed when atoms share electrons • Atoms can share more than one electron • Double bond – two pairs of electrons are shared • Triple bond – three pairs of electrons are shared

8. Polar and Nonpolar Molecules • Not all atoms attract electrons equally • The Polar Water Molecule • Oxygen has a slightly negative bond • Hydrogen a slightly positive bond • Polar means to opposite ends or poles • Nonpolar molecules – same atoms

9. Chemical Shorthand • Symbols to represent elements • Formulas for Molecules • Subscript • Formula – the combination of chemical symbols of the elements that tells what elements are present in a molecule and how many atoms of each element are present Pg 203 1-3