Chemistry Key Points Structure and Bonding
What is chemical bonding?
Chemical bonding is where atoms combine together to form compounds (where two or more
different elements are chemically combined together), there is a change in the arrangement of the
electrons if the outermost shells of each atom. These electrons form links between the atoms and
this is chemical bonding.
3 types of chemical bonds
Ionic -> Between metals and non-metals FeO NaCl
Covalent -> Most non-metallic elements and between non-metals and non-metals CO H2O
Metallic -> In metallic elements and alloy AuAg
Ionic Bonding
Ionic bonding involves the transfer of electrons in the outer shells. Metals such as K or Na lose one
or more electrons to become positively charged ions and obtains a full outer shell. Non-metals such
as O and F gain one or more electrons to become negatively charged ions to have a full outer shell.
These rearrangements occurs because atoms want to conserve as much energy as possible, so it is
easier for metals, for example K, to lose 2 electrons than to gain 6 electrons and vice versa for non-
metals. Group 4 elements don’t bond ionically as it will take the same energy to lose 4 electrons as
to gain 4 electrons so they don’t benefit from bonding ionically. The reason why the ions stay
together is because the oppositely charged ions attract each other and this strong electrostatic force
holds the ions in place.
Representing ionic bonding
The dots and crosses method is used to show ionic bonding. One set of crosses will depict and
indicate the electrons from one atom and one set of dots will indicate the other atom’s electrons.
When an atom loses an electron, you will have to draw the outer shell that has 8 electrons in it.
When an atom gains an electron, you will have to draw the extra electron in the outer shell WITH
the same sign where the electron came from. As well as that, for individual ions, you have to draw
the inner shells as well
Positive ion Negative ion
, When you are told to depict the atomic form of a compound, you just need to draw the outermost
shell of the atom.
Sodium Fluoride (NaF)
Compounds always have neutral charge so in order to neutralise the charge if for example the first
ion has a positive charge of 3 and the second ion has a negative charge of 2. Then you have to find
the LCM of the atomic charge and then place the number before the atom.
Describe and explain how sodium fluoride are held together (5 marks)
1) Sodium loses the outer shell electron to gain a full outer shell
2) Fluorine gains an electron from sodium to gain a full outer shell
3) Sodium becomes a positively charged (+1) ion.
4) Fluorine becomes a negatively charged (-1) ion.
5) Sodium fluoride are held together by strong electrostatic force of attraction between the
oppositely charged ions
Properties of ionic compound
Ionic Lattices
In an ionic compound which is visible, millions and millions of ions are packed together into a regular
cubic arrangement, joined by ionic bonding. This forms a giant 3D structure names an ionic lattice.
Ionic compounds are held together by strong electrostatic forces of attraction between oppositely
charged ion. These forces acts in all directions – therefore meaning that a positive ion is completely
covered by negative ions.
In exams to represent ionic bonding in lattices, draw 9 circles in a 3x3 formation and then identify
the charges of each circle.
Melting and Boiling points
Ionic bonds are strong and require a lot of heat to break them due to the strong electrostatic
attractions which keeps them together. This means that ionic compounds are solid at room
temperature.
What is chemical bonding?
Chemical bonding is where atoms combine together to form compounds (where two or more
different elements are chemically combined together), there is a change in the arrangement of the
electrons if the outermost shells of each atom. These electrons form links between the atoms and
this is chemical bonding.
3 types of chemical bonds
Ionic -> Between metals and non-metals FeO NaCl
Covalent -> Most non-metallic elements and between non-metals and non-metals CO H2O
Metallic -> In metallic elements and alloy AuAg
Ionic Bonding
Ionic bonding involves the transfer of electrons in the outer shells. Metals such as K or Na lose one
or more electrons to become positively charged ions and obtains a full outer shell. Non-metals such
as O and F gain one or more electrons to become negatively charged ions to have a full outer shell.
These rearrangements occurs because atoms want to conserve as much energy as possible, so it is
easier for metals, for example K, to lose 2 electrons than to gain 6 electrons and vice versa for non-
metals. Group 4 elements don’t bond ionically as it will take the same energy to lose 4 electrons as
to gain 4 electrons so they don’t benefit from bonding ionically. The reason why the ions stay
together is because the oppositely charged ions attract each other and this strong electrostatic force
holds the ions in place.
Representing ionic bonding
The dots and crosses method is used to show ionic bonding. One set of crosses will depict and
indicate the electrons from one atom and one set of dots will indicate the other atom’s electrons.
When an atom loses an electron, you will have to draw the outer shell that has 8 electrons in it.
When an atom gains an electron, you will have to draw the extra electron in the outer shell WITH
the same sign where the electron came from. As well as that, for individual ions, you have to draw
the inner shells as well
Positive ion Negative ion
, When you are told to depict the atomic form of a compound, you just need to draw the outermost
shell of the atom.
Sodium Fluoride (NaF)
Compounds always have neutral charge so in order to neutralise the charge if for example the first
ion has a positive charge of 3 and the second ion has a negative charge of 2. Then you have to find
the LCM of the atomic charge and then place the number before the atom.
Describe and explain how sodium fluoride are held together (5 marks)
1) Sodium loses the outer shell electron to gain a full outer shell
2) Fluorine gains an electron from sodium to gain a full outer shell
3) Sodium becomes a positively charged (+1) ion.
4) Fluorine becomes a negatively charged (-1) ion.
5) Sodium fluoride are held together by strong electrostatic force of attraction between the
oppositely charged ions
Properties of ionic compound
Ionic Lattices
In an ionic compound which is visible, millions and millions of ions are packed together into a regular
cubic arrangement, joined by ionic bonding. This forms a giant 3D structure names an ionic lattice.
Ionic compounds are held together by strong electrostatic forces of attraction between oppositely
charged ion. These forces acts in all directions – therefore meaning that a positive ion is completely
covered by negative ions.
In exams to represent ionic bonding in lattices, draw 9 circles in a 3x3 formation and then identify
the charges of each circle.
Melting and Boiling points
Ionic bonds are strong and require a lot of heat to break them due to the strong electrostatic
attractions which keeps them together. This means that ionic compounds are solid at room
temperature.
