1. Warm-up
Determine the number of valence electrons and the charge of an atom of these elements:
Example: Chlorine: 7 valence electrons and -1 charge
Beryllium
Be: 2 valence and Be+2
Sulfur
S: 6 valence and S-2
Fluorine
F: 7 valence and F-1
Oxygen
O: 6 valence and O-2

2. Unit Four, Day One Kimrey 26 September 2012
Chemistry
Unit Four, Day One
Kimrey
26 September 2012

3. Its what happens when elements fall in love!
Chemical Bonding
Its what happens when elements fall in love!

4. 3 Types of Bonds
Covalent bonding
Ionic bonding
Metallic Bonding

5. Covalent Bonding -The perfect relationship
Bond is formed by the sharing of electrons between two nonmetals.
Two types of covalent bond polar and nonpolar.
Polar covalent bond- unequal sharing of electrons.
Nonpolar covalent bond- equal sharing of electrons.

6. Ionic bonding -The stage five clinger
One element steals all the electrons from another.
-or more technically
A transfer of valence electrons between a cation (+) and an anion (-).
Typically between a metal and nonmetal or a metal and polyatomic ion.
ex. NaCl, LiF, CaF2
Polyatomic ion- a group of bonded atoms that have a charge.
ex. OH-, SO42-, etc.

7. Metallic Bonding -when two people merge into one.
Between two metals and forms a sea of electrons.
Attraction between the positive nucleus and surrounding electrons.
Forms a sea of electrons.
This is why metals are malleable and ductile.
Electrons don’t belong to either element – instead just float around the nuclei

8. NEGATIVE POSITIVE ION CATION ANION
Answer these questions:
An atom that gains one or more electrons will have a ____________________ charge.
An atom that loses one or more electrons will have a ____________________ charge.
An atom that gains or loses one or more electrons is called an ____________.
A positive ion is called a ______________ and a negative ion is called an _______________.
NEGATIVE
POSITIVE
ION
CATION
ANION

9. ELECTRONS COMPLETE METAL NONMETAL
What is an ionic bond?
Atoms will transfer one or more ________________ to another to form the bond.
Each atom is left with a ________________ outer shell.
An ionic bond forms between a ___________ ion with a positive charge and a ________________ ion with a negative charge.
Example B1: Sodium + Chlorine Example B2: Magnesium + Iodine
ELECTRONS
COMPLETE
METAL
NONMETAL

10. SHARE COMPLETE NONMETAL
What is a covalent bond?
Atoms ___________ one or more electrons with each other to form the bond.
Each atom is left with a ________________ outer shell.
A covalent bond forms between two _________________.
Example C1: Hydrogen + Hydrogen Example C2: 2 Hydrogen + Oxygen
SHARE
COMPLETE
NONMETAL

11. Electronegativity
The ability of an atom in a compound to attract valence electrons to itself.
Scale of 0-4
Differences in electronegativity is used to determine the type of bond.
0-0.4 = Nonpolar covalent
= Polar Covalent
= Ionic
Example:
Sodium bonded to bromine

12. Practice Identify the following bonds as polar or non-polar covalent:
H bonded to O
H bonded to C
C bonded to F
C bonded to N

14. Formulas for Ionic Compounds
Ionic compounds will bond in a ratio that cancels their ion charge
ALL compounds no matter what are neutral

15. Steps for Writing Formulas
Find the charges of the elements.
Find the simplest ratio needed to cancel out the charges.
Write the ratio numbers as subscripts (ones do not get written!)
Write the positive ion first followed by the negative ion. Make sure not to write the charges of the ions in the formula.

16. Examples Sodium and Chlorine NaCl Potassium and Iodine KI
Calcium and Bromine
CaBr2
Barium and Oxygen
BaO

17. Those pesky polyatomics.
Polyatomic is a group of bonded atoms that still has a charge.
Same steps as binary compounds plus…
5. If a subscript is added to a polyatomic ion place the entire polyatomic in ().
REMEMBER! Never ever change the subscripts in a poly-atomic ion.

18. Examples Sodium and Hydroxide (OH-1) NaOH Lithium and sulfate (SO4-2)
Li2SO4
Calcium and phosphate (PO4-3)
Ca3(PO4)2
Ammonium and fluorine (NH4+1)
NH4F

19. What does all this mean?
The chemical formula tells you the number of each element in that compound.

20. A positively charged ion
1. Complete the chart using your knowledge of atoms.
Vocab Review
1 – What do we call the electrons in the outermost energy level?
2 – What term refers to an atom that has lost or gained electrons?
3 – What is a cation?
4 – What is an anion?
Valence Electrons
Ions
A positively charged ion
A negatively charged ion

21. 2. Ionic Bonds - Draw the Lewis structures for each atom, draw arrows to show the transfer of electrons, write the charge for each ion, and then write the chemical formula.
(A) Potassium + Iodine (B) Magnesium + Oxygen
(C) Lithium + Nitrogen

22. 3. Covalent Bonds – Draw the Lewis structures for each atom, draw circles to show the electrons that are shared, and then write the bond structure and chemical formula.
(A) Fluorine + Fluorine (B) 3 Hydrogen + 1 Phosphorus
(C) 2 Hydrogen + 1 Sulfur

23. Potassium + Iodine Sodium + Oxygen
Calcium + Chlorine Aluminum + Chlorine

24. Chlorine + Chlorine Oxygen + Oxygen
Carbon + 2 Oxygen Carbon + 4 Hydrogen

25. What about other metals?
Other metals charges will always be given in roman numerals.
e.g. I,II, IV
These charges are always positive.
What is the charge of Iron (II)? 2+