chapter2section2interactionsofatoms

							Chapter 2, Section 2

COMBINATIONS OF ATOMS
Interactions of Atoms
 Compounds   – Atoms of more than one
               type of element that have
               been chemically bonded
               together
             – Often have different
               properties than the
               elements that formed
               them
Interactions of Atoms
 Chemical   – Show the ratios and types
 Formulas     of atoms in a compound
               NaCl
               H20
               HCl
Interactions of Atoms

 Chemical     – Describe changes that occur
 Properties    when one substance reacts
               with another substance
Bonding

 Chemical Bond – Force that holds atoms
                   together in a compound
                 – Form when atoms share or
                   exchange electrons in their
                   outermost energy level
                    Outer energy level is
                     considered stable (and won’t
                     form bonds) when it has 8
                     electrons
Bonding
 Covalent   – Form when atoms share the
 Bonds       electrons in their outermost
             energy levels
Bonding

 Molecule   – Group of atoms connected
             by covalent bonds
Bonding
 Ionic Bonds   – Form when oppositely
                charged ions join together
                to form a neutral
                compound
Bonding

 Metallic Bonds – Occur in metals
                 – Electrons are free to move
                   from one positively
                   charged ion to another
                    Results in conductivity
Bonding

 Polar       – Molecules with slight
 Molecules     positive and negative
               charges due to unequal
               sharing of electrons
                Example: Water
Bonding

 Hydrogen   – Weak bonds formed
 Bonds       between the negative end
             of one water molecule and
             the positive end of another
             water molecule
Mixtures

 Mixture   – Two or more substances
            that are not chemically
            combined
Mixtures

 Heterogeneous – Not mixed evenly
 Mixtures      – Each component retains its
                   own properties
Mixtures

 Homogeneous – Evenly mixed
 Mixtures    – Properties of the
                  components are often
                  different from the
                  properties of the mixture
                – Often called a solution
Separating Mixtures and Compounds

  Mixtures vs.   – Mixtures can be separated
  Compounds        by physical means
                 – Compounds must be
                   separated by chemical
                   means