Revision Checklist : 4.2 Bonding and Structure
States of Matter
Gas particles are widely spaced
The three states of matter are solid, liquid and gas.
and in constant quick motion.
Collisions are frequent and elastic.
Melting and freezing between solid and liquid Weak forces between particles.
take place at the melting point.
Boiling and condensing between liquid and gas
take place at the boiling point
Liquids particles are closely spaced
but still in constant motion, and
The amount of energy needed to change state from therefore are constantly colliding.
solid to liquid and from liquid to gas depends on the Forces between particles less than in
strength of the forces between the particles of the solid.
substance. The nature of the particles involved
depends on the type of bonding and the structure of Solid particles can only
the substance. The stronger the forces between the vibrate in a fixed position
particles the higher the melting point and boiling
point of the substance The three states of matter can be represented by a simple
model. In this model, particles are represented by
small solid spheres. Particle theory can help to explain
In chemical equations, the three states of melting, boiling, freezing and condensing.
matter are shown as (s), (l) and (g), with
(aq) for aqueous solutions. Limitations of the simple model include that there are no
forces between the spheres, and that atoms, molecules and
ions are solid spheres. These are not true.
Melting point curve
Pure elements and compounds melt and boil at The temperature will start to
specific temperatures. Solid starts rise again when all the solid
has melted
temperature
Melting point and boiling point data can be used melting at this
to distinguish pure substances from mixtures. point
• A pure substance will melt or boil at a fixed A pure solid will melt at a fixed
temperature. temperature and the line will
• A mixture will melt over a range of stay horizontal when it is
temperatures and not a sharp melting point melting.
time
The temperature does not rise when the solid
is melting because the heat is absorbed to
break the bonds between the solid particles
N Goalby chemrevise.org 1
, Ionic bonding
Metal atoms lose electrons to become
Ionic bonding occurs in compounds formed from metals
positively charged ions. Non-metal atoms
combined with non-metals.
gain electrons to become negatively charged
When a metal atom reacts with a non-metal atom electrons in
ions.
the outer shell of the metal atom are transferred.
The electron transfer during the formation of an ionic
compound can be represented by a dot and cross diagram eg
for sodium chloride
+ -
xx
xx
x
x Na Cl x
Na x Cl x x
xx
xx
Just showing outer shell electrons
In sodium chloride, the sodium atom loses one electron away forming a +1 ion. The chlorine gains
the one electron to become a -1 ion.
The ionic bond is the force of attraction between the oppositely charged ions
The ions produced by metals in Mg2+ = [2,8]2+
Groups 1 and 2 and by non-metals in Ca2+ = [2,8,8]2+
Groups 6 and 7 have the electronic Cl- = [2,8,8]-
structure of a noble gas (Group 0). O2- = [2,8]2-
Working out Formulae for Ionic Compounds
Common charges of Ions Group 1 always form +1 ions e.g. Na+
The charge on the ions produced by metals in Groups 1 Group 2 always form +2 ions e.g. Mg2+
and 2 and by non-metals in Groups 6 and 7 relates to Group 6 always form -2 ions e.g. O2-
the group number of the element in the periodic table Group 7 always form -1 ions e.g. F-
Using the ions in group 1,2,6,7 you should be able To do this ions are combined together so that the
to work out the formulae of compounds. You may total positive charge of the ions is the same as the
also be given other ions to use total negative charge of the ions – giving a neutral
compound
For sodium chloride the ions are Na+ and Cl-. Here the +1 charge cancels the -1 charge so the formula is NaCl
For magnesium fluoride the ions are Mg2+ and F-. Here we need two F- ions to cancel out the +2 charge on the
Mg, so the formula is MgF2
For Lithium Oxide the ions are Li+ and O2-. Here we need two Li+ ions to cancel out the -2 charge on the O, so
the formula is Li2O
N Goalby chemrevise.org 2
States of Matter
Gas particles are widely spaced
The three states of matter are solid, liquid and gas.
and in constant quick motion.
Collisions are frequent and elastic.
Melting and freezing between solid and liquid Weak forces between particles.
take place at the melting point.
Boiling and condensing between liquid and gas
take place at the boiling point
Liquids particles are closely spaced
but still in constant motion, and
The amount of energy needed to change state from therefore are constantly colliding.
solid to liquid and from liquid to gas depends on the Forces between particles less than in
strength of the forces between the particles of the solid.
substance. The nature of the particles involved
depends on the type of bonding and the structure of Solid particles can only
the substance. The stronger the forces between the vibrate in a fixed position
particles the higher the melting point and boiling
point of the substance The three states of matter can be represented by a simple
model. In this model, particles are represented by
small solid spheres. Particle theory can help to explain
In chemical equations, the three states of melting, boiling, freezing and condensing.
matter are shown as (s), (l) and (g), with
(aq) for aqueous solutions. Limitations of the simple model include that there are no
forces between the spheres, and that atoms, molecules and
ions are solid spheres. These are not true.
Melting point curve
Pure elements and compounds melt and boil at The temperature will start to
specific temperatures. Solid starts rise again when all the solid
has melted
temperature
Melting point and boiling point data can be used melting at this
to distinguish pure substances from mixtures. point
• A pure substance will melt or boil at a fixed A pure solid will melt at a fixed
temperature. temperature and the line will
• A mixture will melt over a range of stay horizontal when it is
temperatures and not a sharp melting point melting.
time
The temperature does not rise when the solid
is melting because the heat is absorbed to
break the bonds between the solid particles
N Goalby chemrevise.org 1
, Ionic bonding
Metal atoms lose electrons to become
Ionic bonding occurs in compounds formed from metals
positively charged ions. Non-metal atoms
combined with non-metals.
gain electrons to become negatively charged
When a metal atom reacts with a non-metal atom electrons in
ions.
the outer shell of the metal atom are transferred.
The electron transfer during the formation of an ionic
compound can be represented by a dot and cross diagram eg
for sodium chloride
+ -
xx
xx
x
x Na Cl x
Na x Cl x x
xx
xx
Just showing outer shell electrons
In sodium chloride, the sodium atom loses one electron away forming a +1 ion. The chlorine gains
the one electron to become a -1 ion.
The ionic bond is the force of attraction between the oppositely charged ions
The ions produced by metals in Mg2+ = [2,8]2+
Groups 1 and 2 and by non-metals in Ca2+ = [2,8,8]2+
Groups 6 and 7 have the electronic Cl- = [2,8,8]-
structure of a noble gas (Group 0). O2- = [2,8]2-
Working out Formulae for Ionic Compounds
Common charges of Ions Group 1 always form +1 ions e.g. Na+
The charge on the ions produced by metals in Groups 1 Group 2 always form +2 ions e.g. Mg2+
and 2 and by non-metals in Groups 6 and 7 relates to Group 6 always form -2 ions e.g. O2-
the group number of the element in the periodic table Group 7 always form -1 ions e.g. F-
Using the ions in group 1,2,6,7 you should be able To do this ions are combined together so that the
to work out the formulae of compounds. You may total positive charge of the ions is the same as the
also be given other ions to use total negative charge of the ions – giving a neutral
compound
For sodium chloride the ions are Na+ and Cl-. Here the +1 charge cancels the -1 charge so the formula is NaCl
For magnesium fluoride the ions are Mg2+ and F-. Here we need two F- ions to cancel out the +2 charge on the
Mg, so the formula is MgF2
For Lithium Oxide the ions are Li+ and O2-. Here we need two Li+ ions to cancel out the -2 charge on the O, so
the formula is Li2O
N Goalby chemrevise.org 2
