1. The way things are joined together
Bonding
The way things are joined together

2. 24 12 Mg
electron - 12
proton +
neutron

3. Atoms can be joined together in 3 possible ways
Metal and non-metal
Non-metals only
Metals only
Ionic Bonding
Covalent Bonding
Metallic Bonding
All three types involve changes in the electrons in the outermost electron shells of the atoms

4. Ionic bonds
+ and - charges

5. Most ionic compounds contain a metal and a non-metal.
When metals react they lose outer shell electrons to leave a full electron shell.
This produces a charged atom (ion) with a + charge.
Lose 1 or more electrons
Neutral atom n+
Positive ion
When non-metals react with a metal they gain electrons to achieve a full electron shell.
Gain 1 or more electrons
Neutral atom n-
Negative ion

6. Has ? Electrons in outer shell19 9 F
Has ? Electrons in outer shell
Does it need to pick up or lose electrons to make the outer shell full

7. Now has more negative electrons than positive protons
Gains 1 electron
Now has more negative electrons than positive protons
= a negative charge 19 9 F

8. Now has more positive protons than negative electrons24 12 Mg
Loses 2 electrons
Now has more positive protons than negative electrons
= a positive charge

9. Cl Cl Na Na+ Loses 1 electron Sodium atom (2.8.1)
Sodium 1+ ion (2.8.0) Cl Cl
Gains 1 electron
(from sodium)
Chlorine atom (2.8.7)
Chlorine I - ion (2.8.8)

10. The oppositely charged ions are attracted into a lattice that gets bigger and bigger until it consists of millions of ions + - + -
opposites
attract

11. We have shown ions attracting and building into a 2 dimensional sheet.+ -
In fact the whole process will be going on in three dimensions to build up a giant 3-D lattice. + - + -

12. Ionic compounds are very brittle.
Opposite charges attract, so neighbouring ions are pulled together.
When something hits the substance a layer of ions will be pushed so that they are next to ions with the same charge.
Attraction becomes: + - + -
repulsion! + -
Blow - +

13. Ionic substances do not conduct electricity as solids.
When molten or dissolved they will conduct (and also undergo electrolysis).
This is because the electricity is carried through the solution by the ions which are free to move when the ionic compound is molten or in solution. + -
Solid – not free to move Doesn’t conduct - +
Molten – mobile Does conduct

14. The ionic bonds are very strong.
Will that make ionic compounds have a high or low boiling point?
High

15. Covalent bonding
Sharing.

16. Covalent compounds are formed when non-metal atoms react together.
The atoms share electrons

17. - F Covalent compounds are held together by this sharing of electrons.
A pair of electrons shared in this way is known as a covalent bond.
It is sometimes represented in full bonding diagrams (see figure 1). Often these bonds are just shown as a pair of electrons (xx) or even just a line (see figure 2). F X -
Figure 1
Figure 2

18. There can be small covalent molecules and large covalent molecules

19. Chlorine (2.8.7) needs 1 more electron to attain a full electron shell.Cl
(2,8,7) Cl
(2,8,7)
Cl-Cl Cl
(2,8,8) Cl
(2,8,8)

20. Hydrogen (1) needs 1 more electron but oxygen (2. 6) needs 2 more
Hydrogen (1) needs 1 more electron but oxygen (2.6) needs 2 more. Therefore, we need 2 hydrogens. O H O H O H

21. The bonds between ATOMS that share electrons are STRONG
The bonds between molecules that don’t share electrons are WEAK
What effect will this have on the melting and boiling points?
Will they be high or low?
Low

22. Do these covalent molecules conduct electricity?
Will they dissolve in water and spread out like ionic solids? No No

23. Metallic bond

24. The protons sit in a sea of electrons
Metallic bonding is the attraction of + metal ions for the “sea of electrons.”

25. The metal atoms are the same and exist in simple structures.
Metals are not brittle.
The metal atoms are the same and exist in simple structures.
If something hits the substance, it simply moves to the next layer along.
Blow

26. If the sea of electrons can flow, will metals conduct electricity?
Like ionic bonds the metallic bonds are strong. Will melting points be high or low?
High
If the sea of electrons can flow, will metals conduct electricity?
yes

28. Name of chemical
Sucrose
Sodium chloride
Ethanol
Copper sulphate
Melting point – high or low
Does it conduct electricity as a solid?
Does it conduct electricity in aqueous solution