1.1 Compounds are substances in which atoms of two or more
elements are chemically combined.
1.1.1 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.
184.108.40.206 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).
220.127.116.11.1 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
18.104.22.168.1.1 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
22.214.171.124.1.1.1 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.
126.96.36.199.188.8.131.52 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,
H2O, NH3 and CH4. Others have giant covalent structures
(macromolecules), such as diamond and silicon dioxide.
184.108.40.206.220.127.116.11.1 Metals consist of giant structures of atoms arranged in a regular pattern.
18.104.22.168.22.214.171.124.1.1 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.