1. Molecules Molecule is combination of two or more atoms, these may be of the same element as oxygen molecule O 2 or different elements as in the hydrogen chloride (HCL). Amore complicated molecule is that of glucose C 6 H 12 O 6

3. Stability of the atom When the atom become stable when contain the highest energy level has eight electron so must bond with other atom to become more stable Symbols and formula explain the structure of molecule NaCL indicated the compound (sodium chloride ) consist of sodium and chlorine Na (sodium) + (Cl)chlorine)

4. Symbols and formula Formula molecular explain the structure of molecule For example C 6 H 8 O 6 Contain six atom +eight atom of hydrogen+ six atom of oxygen

5. HNO 3 ( 1H+ 1N+3(O) nitric acid K 2 Cr 2 O 7 ( 2K+ 2Cr+7(O) potassium dicromate O 2 (2O) Oxygen H 2 O (O+ 2H) Water

6. Formation of ions Stability of the atom When the atom become stable when contain the highest energy level has eight electron so must bond with other atom to become more stable

7.  Na atom has 11 protons and 11 electrons.  It has only 1 valence electron. If it loses it  Therefore, Na becomes more stable by losing an e -  Na. →Na + 11+ Howard Howson, Eastside HS, Paterson NJ.

8.  But with 11 protons and 10 electrons, Na will have a charge of 1+.  The resulting cation is written as Na + + 11+ Howard Howson, Eastside HS, Paterson NJ.

9.  This loss of e- can be expressed in an equation: Na  Na + + e -  Magnesium atoms will lose 2 e- to obtain a full outer shell. The equation is: Mg  Mg 2+ + 2e -  Aluminum forms a 3+ cation by losing 3 e-. The equation is: Al  Al 3+ + 3e - 11+ Howard Howson, Eastside HS, Paterson NJ.

10.  When a neutral atom loses an electron, the resulting positively charged ion is called a cation.  We know from our definition of metals that they will lose electrons, and thus usually form cations. 11+ Howard Howson, Eastside HS, Paterson NJ.

11.  Cl now has 17 protons and 18 electrons, producing a charge of 1–.  The resulting anion is written as Cl – – 17+ Howard Howson, Eastside HS, Paterson NJ.

12.  This gain of e- can be expressed in an equation: Cl + e -  Cl -  Oxygen atoms will gain 2 e- to obtain a full outer shell. The equation is: O + 2e -  O 2-  Anions are named by dropping the ending and adding –ide to the end of the element name Example, Cl - is chloride ion, O 2- is oxide ion. 17+ Howard Howson, Eastside HS, Paterson NJ.

13. Size of ions become small Size of ions become large

14. Type of chemical bond Ionic bond Covalent bond

15. Ionic Bond Between atoms of metals and nonmetals with very different electronegativity Bond formed by transfer of electrons. Examples; NaCl, CaCl 2

17. 1). Ionic bond – electron from Na is transferred to Cl, this causes a charge imbalance in each atom. The Na becomes (Na + ) and the Cl becomes (Cl - ), charged particles or ions.

18. Naming of ionic compound What the name of the compound CaBr 2 Name of positive ion followed by stem of negative ion +ide Calcium positive charge Br bromine negative charge First write calcium Second write stem of negative charge Brom +ide Calcium bromide

19. COVALENT BOND bond formed by the sharing of electrons for example N 2 - CO 2 -CL 2 - NH 3

21. type of covalent bond Signal covalent bonddouble covalent bond triple covalent bond CL – CL CL 2 0=C=O CO 2 N N 2