1. Chemical Bonding

2. How do elements combine to form compounds?

3. Chemical Bonds- Force of attraction that holds 2 or more elements together

4. Octet Rule = atoms tend to gain, lose or share electrons so as to have 8 valence e’s
C would like to
N would like to
O would like to
Gain 4 electrons
Gain 3 electrons
Gain 2 electrons

5. Chemical bonds: an attempt to fill electron shells
Some types of bonds are:
Ionic bonds – transfer e’s; metal to non-metal
Covalent bonds – share e’s; 2 non-metals
Metallic bonds – e’s flow from metal atom to metal atom

6. IONIC BOND- Bond formed between two ions by the transfer of electrons from a metal to a non-metal.

7. Metals usually have <4 valence e’s so lend e’s Non-metals usually have >4 valence e’s and borrow e’s

8. Review Ionic Bonds – show transfer of electrons from metal to nonmetal
-Metals give up valence electrons (to see 8 in lower shell.
-Nonmetals receive electrons (enough to see 8 valence e’s
The result is the formation of positive and negative ions that are bonded by electrostatic attraction

10. Ionic Compounds -High melting and boiling pts
Ionic Compounds -High melting and boiling pts. -Crystal lattice -Form electrolytes when dissolved in water (conduct electricity) -solid at room temp.

12. REVIEW QUESTIONS What part of the atom is involved in ionic bonding?
Ionic compounds are made of one element that is a __________ and one element that is a ____________.
What is an ion?
Valence electrons
metal
nonmetal
A charged particle

13. REVIEW QUESTIONS
give up
4. Metals will _______ electrons and become ions with a __________ charge.
5. Non metals will _______ electrons and become ions with a ________ charge.
6. An ion with a +3 charge means the atom has _________________ electrons.
positive
receive
negative
given up 3

14. REVIEW QUESTIONS
7. An ion with a -2 charge means that the atoms has _______________ electrons.
8. The formula for potassium chloride would be ______________.
received 2
KCl

15. Show bonding animation: http://www. youtube. com/watch

16. COVALENT BOND bond formed by the sharing of electrons

17. Covalent Bond Between two or more non-metals.
Formed by sharing electron pairs
# of bonds = the number of valence e’s needed to total 8.

18. Covalent Compounds -Low melting pts and b. p
Covalent Compounds -Low melting pts and b.p. -Solids, liquids and gases at room temp -Non-electrolytes

19. Covalent Bonds

20. 2. Covalent bonds- Two atoms share one or more pairs of outer-shell electrons.
Oxygen Atom
Oxygen Atom
Oxygen Molecule (O2)

21. lets look at the molecule Cl2-
lets look at the molecule Cl2 Cl Cl Cl +
Shared
Electrons

22. Hydrogen is happy with 2 electrons.- H
H O 2 O H H H
Hydrogen is happy with 2 electrons.

23. - N
Nitrogen has three spots for bonding, and shares three pairs of electrons.

24. Each nitrogen has a set of electrons that are not available for bonding. Nitrogen can only make 3 bonds. N N
These triple bonds are very strong, and have a very high bond energy. therefore it is a very stable bond.

25. Lewis Dot Diagrams, used to represent covalent bonds
Can also use lines to represent bonds
There are three types of bonds, single, double, and triple.

26. - H H
SINGLE
DOUBLE N
TRIPLE N

27. Ionic vs. Covalent Bonds
Ionic Bonds
Form when electrons are exchanged between atoms.
Form between a metal and a non-metal.
Covalent Bonds
Form when electrons are shared between atoms.
Form between two non-metals.
Both types of bonds result in all atoms having a full outer energy level.

28. Ionic Compounds
Covalent Compounds
High m.p., b.p
Low m.p., b.p.
Solid at room temp
Solid, liquid, gas at room temp.
Dissolved in water: electrolytes
Dissolved in water: non-electrolytes

29. Practice State type of bond: NaCl; Ionic Bond C2H6; Covalent Bond
Na(CO3)2;
Ionic & Covalent

30. METALLIC BOND Force of attraction between positively charged metal ions and the electrons in a metal.

31. Metallic Bond, A Sea of Electrons

32. Metallic Bond Formed between atoms of metallic elements
Valence electrons flow from one atom to the next and form a combined electron cloud around atoms
Good conductors at all states, lustrous, very high melting points, malleable

33. Metals Form Alloys Metallic bonds form
alloys which is a solution of a metal in a metal.
Examples are
Brass – mix of Cu and Zn
Bronze – mix of Cu and Sn
Pewter – mix of Sn, Cu, Sb

35. Credits
education.jlab.org/jsat/powerpoint/chembond.ppt