Atomic Bonding

1. Atomic Bonding Ch 19 sects1 & 2

2. Combining Elements • Elements that are unstable will combine with other elements to become stable • Unstable = Wants to change = ready to react • Stable = wants to stay the same • Elements that have combined to be stable are known as compounds • Compounds take on new properties • Properties-The way it looks and behaves

3. Examples of Compounds andNew properties • Na in water is highly reactive (Metal) • Sodium and Water • Chlorine is highly reactive (gas) • Sodium and Chlorine are unstable elements that combine to become stable (table salt) • When Na and Cl combine to form NaCl the new chemical properties cause it to become stable and it only dissolves in water

4. Chemical Formulas • Chemical formulas are used to show which elements are in a compound • Chemical formulas also tell you how much of each element is involved • C12H22O11 = Sucrose (cane sugar) • Which elements are part of sucrose? • How many of each element form sucrose?

5. Atomic Stability • Atoms want a full outer valence so they can become stable • Atoms will gain, lose, or share electrons to become stable • The elements in column 8 (18) on the periodic table have full outer valences • These elements are known as noble gases • These elements are chemically stable

6. Factors That Affect Bonding • How many electrons the atom needs • If an element only needs to gain/lose 1 electron it will usually form an ionic bond • The electronegativity of the elements involved • Electronegativity describes how bad an atom wants an electron/How strong is its pull

7. Using Electronegativity • Find the electronegativity of the elements forming the bond • Larger electronegativity (minus) smaller electronegativity (should always be a positive number) • Find what type of bond it is (Listed above the chart)

8. Types of Bonds • There are 2 major types of bonds • Covalent bonds-Elements share electrons to have a full outer valence • Covalent bonding will be broken down into two more categories • Ionic bonds-Elements give or take electrons • Remember when an element changes its number of electrons it also changes its overall charge

9. Covalent Bonding • Covalent bonding is the sharing of electrons and it is broken into two different types • Non-polar Covalent Bonding-Equal sharing of electrons • Elements have a similar electronegativity • Because the electrons are shared evenly there is no change in the charges of the atoms

10. Covalent Bonding • Polar Covalent Bonding-Atoms are shared unequally between atoms • One atom will have a greater electronegativity • The atom with the greater electronegativity will have a stronger pull on the electron • Since the electron spends more time around one of the elements that element will have a slight (-) charge

11. Ionic Bonding • Ionic bonding forms when one atom gives up an electron and another atom takes that electron • Forms between an atom with a weak electronegativity and an atom with a strong electronegativity • Usually between a metal and non-metal • Usually between atoms from the right side of the periodic table and the left side of the periodic table

12. Ionic Bond • forming an ionic bond