3. •To write formulae for ionic compounds from given symbols and ionic
charges
to represent the electronic structure of the ions in sodium chloride,
magnesium oxide and calcium chloride in the following forms:
You should be able to:
for sodium ion (Na+)
4. You should be able to:
•to represent the covalent bonds in molecules such as water,
ammonia, hydrogen, hydrogen chloride, chlorine, methane and
oxygen and in giant structures such as diamond and silicon
dioxide in the following forms:
5. You should be able to:
•To represent the bonding in metals in the following form:
6.
7.
8.
9. a) Compounds are substances in which atoms of two or more elements are
chemically combined.
10. b) Chemical bonding involves either transferring or sharing electrons in
the highest occupied energy levels (shells) of atoms in order to achieve the
electronic structure of a noble gas.
TOTTERDOWN
11. c) When atoms form chemical bonds by transferring electrons, they form
ions. Atoms that lose electrons become positively charged ions. Atoms that
gain electrons become negatively charged ions. Ions have the electronic
structure of a noble gas (Group 0).
12. Element Symbol Group Charge
Potassium
K 1 1+
Magnesium
2+
Lithium
1
Ba 2+
Aluminium
Na 1 1+
Chloride
Cl-
Bromide
Br- 1-
Flouride
F-
Oxide
O2-
Sulfide
S2-
13. Element Symbol Group Charge
Potassium
K 1 1+
Magnesium
Mg 2 2+
Lithium
Li 1 1+
Barium
Ba 2 2+
Aluminium
Al 3 3+
Sodium
Na 1 1+
Chloride
Cl- 7 1-
Bromide
Br- 7 1-
Flouride
F- 7 1-
Oxide
O2- 6 2-
Sulfide
S2- 6 2-
14. d) The elements in Group 1 of the periodic table, the alkali metals, all react with
non-metal elements to form ionic compounds in which the metal ion has a
single positive charge.
Sodium transfers an electron (to chlorine) and so becomes positively charged
Chlorine gains an electron so becomes positively charged
15. e) The elements in Group 7 of the periodic table, the halogens, all
react with the alkali metals to form ionic compounds in which the
halide ions have a single negative charge.
16. Mg + 2F → MgF2
The ratio of ions is:
Mg 2+ : F1+
1: 2
So the formula of the compound is MgF2
17. Fluoride F- Oxide O 2- Carbonate
CO3
2-
Phosphate
PO4
3-
Lithium Li+
Barium Ba 2+
Copper Cu2+
Aluminium Al3+
Complete the following table with the formula of each compound
formed.
You do not need to remember the charges on the ions – these are
given in the data sheet
19. f) An ionic compound is a giant structure of ions. Ionic
compounds are held together by strong electrostatic forces
of attraction between oppositely charged ions. These
forces act in all directions in the lattice and this is called
ionic bonding.
20. g) When atoms share pairs of electrons, they form covalent
bonds. These bonds between atoms are
strong. Some covalently bonded substances consist of
simple molecules such as H2, Cl2, O2, HCl, O,
NH3 and CH4.
21. Others have giant covalent structures (macromolecules), such as
diamond and silicon dioxide.
The giant structure of
diamond
The giant
structure of silicon
22. Property Ionic Covalent
Melting point High
Solubility soluble in water doesn’t usually
mix with water
Electrical
conductivity
high low
23. h) Metals consist of giant structures of atoms
arranged in a regular pattern.
The atoms in metals are closely packed
together and arranged in regular layers.
This means they can form crystals.
24. i) The electrons in the highest occupied energy levels (outer shell) of
metal atoms are delocalised and so free to move through the whole
structure. This corresponds to a structure of positive ions with electrons
between the ions holding them together by strong electrostatic
attractions. (HT)
25. Why do atoms bond?
They want to have a full outer electron shell.
This is why oxygen that we breathe in is O2, chlorine gas is
Cl2 etc…
METAL NON-METAL
METAL
NON-METAL
What type of bond?
metallic ionic
ionic covalent
26. What are the properties of the different
types of chemical bond?
IONIC METALLIC COVALENT COVALENT
Type of
structure
Are ions
present?
Are delocalised
electrons
present?
How strong is
the chemical
bond?
High/Low
melting point?
Conductor of
electricity?
27. What are the properties of the different
types of chemical bond?
IONIC METALLIC COVALENT COVALENT
Type of
structure giant giant Giant
Simple
molecules
Are ions
present? yes yes no no
Are delocalised
electrons
present?
no yes no (except
in graphite)
no
How strong is
the chemical
bond?
strong strong
very
strong
very
strong
High/Low
melting point? high high very high low
Conductor of
electricity?
when molten/
in solution yes no (except
graphite)
no
28. Ionic bonds
Make sure you know how to draw the electrons on a diagram to
show both atoms and ions
Don’t forget to add the charge when drawing diagrams of ions!
(Use a square bracket and write the charge top right).
Remember – ions have a full outer shell.
What is an ionic bond?
29. Why do ionic substances have high melting points?
Why can ionic substances conduct electricity when they are
molten or in solution, but not when they are solid?
31. Why do giant covalent substances such as diamond or carbon
have very high melting points?
Why do simple covalent bonds have lower melting points?
32. Small molecules Giant covalent structure
Put these in the correct place:
Methane CH4 Silicon dioxide SiO2 Diamond C Ammonia NH3
33. Small molecules Giant covalent structure
Methane CH4
Silicon dioxide SiO2
Ammonia NH3
Diamond C
Put these in the correct place:
34. Sodium Chloride
Magnesium oxide
Calcium Chloride
Hydrogen Sulfide
Iron (II) chloride
Iron (III) chloride
Sodium Sulfide
Sodium Sulfate
Calcium Hydroxide
Magnesium Nitrate
Sodium carbonate
Write the correct formula for these compounds
35. Sodium Chloride NaCl
Magnesium oxide MgO
Calcium Chloride
Hydrogen Sulfide
Iron (II) chloride
Iron (III) chloride
Sodium Sulfide
Sodium Sulfate Na2SO4
Calcium Hydroxide Ca(OH) 2
Magnesium Nitrate Mg(NO3) 2
Sodium carbonate Na2CO3
Write the correct formula for these compounds
36.
37.
38. H2 gas insoluble no
S8 solid insoluble no
H2O liquid n/a low
CO2 gas slightly soluble no
C25H52 solid insoluble no
C12H22O11 solid Insoluble no
42. Giant Ionic Structures
Oppositely charged ions are
attracted to each other.
This attraction forms a strong
ionic bond.
The charge on a ion acts in
all directions.
The ions arrange themselves
into a lattice structure,
involving huge numbers of
ions, which is why they are
named giant structures.
43. Because of this, an electric current can be passed
through the solution.
The same is true when ionic substances are molten.
When an ionic
substance
dissolves, the
ions break out of
their lattice
structure and are
free to move
about and carry
a charge.
44. When atoms share electrons, they are
held together very tightly. This is a
covalent bond.
Example – Hydrogen:
H H
x
H Hx
Hydrogen atoms Hydrogen molecule
H2
45. You are very likely to get a question about why giant
covalent substances (like diamond or silicon dioxide –
sand) have very high melting points.
Lots (thousands,
millions!) of atoms
joined together by
covalent bonds
• very strong bonds
• lots of bonds to be broken
• need a huge amount of
energy/heat to break the bonds
• therefore a very high melting
point
48. Simple molecules all have low melting and
boiling points.
Why?
H Hx
The covalent bonds are very
strong, so the atoms are held
together tightly.
But, the individual molecules
are separate from each
other.
There is a force of attraction between individual molecules
(called the intermolecular force). This is weak, and only
a small amount of energy is needed to overcome it.
H H
50. Finally, metallic bonds
• outer shell electrons delocalise (come away from the atom) and are
free to move
• forming a ‘sea of electrons’ and leaving positive metal ions
• the attraction between negative electrons and the positive ions
holds the metal together – the electrons act like glue
• the metal ions are held tightly in neat rows that can slide over each
other
