1. November 5, 2015 BELLRINGER: Why do elements bond with other elements?
WHEN FINISHED WITH THE BELLRINGER:
Pick up Great Combinations Packet

2. Goals To explain the difference between the types of bonds.
To identify what bond is present in a chemical compound.
To draw chemical bonds

3. Q: Why do atoms bond?
Atoms bond because they want to have a full valence shell (outer shell)
Full shell would have 8 e- in them
Exception: H and He only want 2 (b/c they only have one energy level)

4. Q: Why do atoms bond?
Atoms can either get rid of electrons (become more positive- cations) or gain electrons (become more negative- anions)
Atoms can also share electrons

5. Q: What are the types of chemical bonds?
There are 2 types of chemical bonds: ionic bonds and covalent bonds.
There are also metallic bonds (between 2 metals), but we won’t talk much about those

6. 1. Ionic Bonds (Give and Take)
This type of bond is formed between IONS (positive cation and negative anion)
Remember: Opposites attract
In this bond, one atom gives up electrons and the other takes those electrons for itself

7. 1. Ionic Bonds (Give and Take)
NaCl (Sodium Chloride) is a perfect example
Draw the Lewis diagram for Sodium.

8. Sodium How many valence electrons does it have?
1 (first column = first family/group)
How many more does it need to be complete? 7
Is it easier for Sodium to gain those electrons or get rid of the one it has?
Easier to get rid of 1, than gain 7

9. Sodium
Sodium will give up its 1 valence electron to another element (Chlorine)
Which elements want that one electron? Why?
Halogens (they have 7 e- so need only 1 more)

10. Sodium and Chlorine

11. Ionic Bonds
NOTICE: Electrons want to have pairs of electrons, unpaired electrons are unstable and want a partner.

12. What charge will these atoms have in an ionic bond?
Alkali metals= +1
They will give up their one valence electron, which makes them have one more proton than electron
Alkaline earth metals = +2
They will give up their 2 valence e-, which makes them have 2 more p+ than e-.

13. What charge will these atoms have in an ionic bond?
Boron family = + 3
They will give up their 3 valence e-, which makes them have 3 more p+ than e-
Carbon family = +/- 4
It is just as easy for them to gain 4 e- as it is for them to lose 4 e-, so these can go either way

14. What charge will these atoms have in an ionic bond?
Nitrogen Family = -3
They will gain 3 e-, which makes them have 3 more e- than p+
Oxygen Family = -2
They will gain 2 e-, which makes them have 2 more e- than p+

15. What charge will these atoms have in an ionic bond?
Halogens = -1
They will gain 1 e-, which makes them have 1 more e- than p+
Noble Gases = 0
They already have 8 e- and don’t need anymore, so their number of e- = number of p+

17. Ionic Bonds
Ionic Bonds are not always a 1:1 ratio, you might need more than 2 atoms.

18. Ionic Bonds Example
Calcium has 2 valence e- to give up

19. Ionic Bond Example
A calcium atom can give it’s electrons to 2 atoms of fluorine (each fluorine has 7 valence e-)
The chemical formula for this would be CaF2 which tells me I have 1 atom of calcium and 2 of fluorine

20. Ionic Bonds Ionic bonds form between METALS and NONMETALS
Metals like to give up electrons, nonmetals like to steal them

21. Agenda Items Part 1 of HW pkt due tomorrow
EXAMPLE: Strontium and Bromine