2. Between different molecules Metal-Nonmetal Gain or loss of electrons Nonmetal-Nonmetal Sharing of electrons Within a compound (between elements) Unequal sharing of electrons Equal sharing of electrons Metals Surrounding sea of electrons When H bonds to N, O, F Occurs in proteins

4.  FORCES What is a chemical bond? The force that holds two atoms together

5. ● Intramolecular Force (stronger) holds elements together to make compounds ● Intermolecular Force (weaker) holds molecules together to form solids, liquids, and gases

6. Intramolecular Force – The force within a compound between atoms. Example: the bond between O and H in a H 2 O molecule

7.  Example: the bond between Na and Cl in a NaCl molecules Na + Cl -

8. ● Ionic Bond (strongest) – electrostatic attraction between a metal and nonmetal that involves a gain or loss of electrons ● Covalent Bond – between two nonmetals that involves a sharing of electrons ● Metallic Bond – between metal atoms and the surrounding sea of electrons

10. ● Ionic Bond (strongest) – between a metal and nonmetal that involves a gain or loss of electrons ● When an atom loses a valence electron to another atom, it becomes a (+) ion. This is a CATION. ● When an atom accepts a valence electron from another atom, it becomes a (-) ion. This is an ANION.

11. FULL OCTET

12. Cl Na EXAMPLE 1 valence e- 7 valence e-

13. Cl Na EXAMPLE 8 valence e- Cation – Na +1 Anion – Cl -1

14. Ca 2+ S 2-

15. Shows the # of valence elecrons the atom has What is the charge on Ca? 2+1- What is the charge on F? How many atoms of Ca and F are needed? DROP AND SWITCH THE CHARGES

16. Ca 2+ F -1 Drop Ca 2 F 1 Switch CaF 2

17. Drop Na 1 N 3 Switch Na 3 N 1+ 3-

18. 1. # of valence electrons in aluminum? 2. Change in electrons for octet? 3. Ionic charge of aluminum? 3 Lose 3 e - Al 3+

19. ● Sharing of electrons H-H = H 2

20. ● Polar Covalent Bond – electrons are unevenly shared; different EN values ● Nonpolar Covalent Bond – electrons are evenly shared; same or very close EN values

21. Electronegativity is the tendency of an atom to attract other atoms’ valence electrons ● The more electronegative the atom, the stronger the attraction for electrons ● Fluorine is the most electronegative atom on the periodic table

22. ● Fluorine the Flirt likes to attract other atoms’ valence electrons Examples: H-F (polar) H-H (nonpolar)

23. The O atom pulls on the shared electrons in each H causing a partial (+) charge on each H atom and partial (–) charge on the O atom Why is O pulling the electrons towards itself? O is more electronegative and attracts the electrons – unequal sharing of electrons Why does water act like a magnet? Because the (+) attracts the (-)

24. ● Free floating electrons among metals

25. Intermolecular Force – The force between different molecules  Example: an interstate highway runs between different states

26. Intermolecular Force Intramolecular Force

27. Intermolecular Force Intramolecular Force

28. ● Hydrogen Bond – when H bonds to N, O, or F o Important in DNA (genetic material), proteins, and water molecules ● Disulfide Bond – occurs in proteins to ensure proper functioning and prevent destruction from extreme environments ● Peptide Bond – occurs between amino acids in DNA.

30. Single bond Share one pair of electrons Double bond Share two pairs of electrons

32. ● Why do atoms form chemical bonds? How? ● What does it mean when an atom is chemically unstable? ● What does the octet rule state? ● What subatomic particle is involved in forming chemical bonds? ● What is a molecule? ● How can the periodic table be used to determine the # of valence electrons? ● How can the periodic table be used to determine the # of energy levels? ● Most matter is electrically neutral, why? To become more stable by losing, gaining, or sharing electrons It does not have a full octet of electrons The outermost energy level has 8 valence electrons (full shell) Valence electrons Two or more elements chemically combined together Look at the group number (Transition Metals are different) Look at the period number The # of protons cancels out the # of electrons