IGCSE Chemistry
2026 - 2028
Syllabus Checklist ✅
Topic 2: Atoms, Elements, and Compounds
Elements, Compounds, and Mixtures
Describe the differences between elements
, compounds
, and mixtures
Atomic Structure and the Periodic Table
Describe the structure of the atom
as a central nucleus
containing neutrons
and protons
, surrounded by electrons
in shells
State the relative charges
and relative masses
of a proton
, a neutron
, and an electron
Define proton number
/ atomic number
as the number of protons
in the nucleus
of an atom
Define mass number
/ nucleon number
as the total number of protons
and neutrons
in the nucleus
of an atom
Determine the electronic configuration
of elements and their ions with proton number 1 to 20 (e.g. 2,8,3)
State that Group VIII noble gases
have a full outer electron shell
State that the number of outer shell electrons
is equal to the group number
in Groups I to VII
State that the number of occupied electron shells
is equal to the period number
Isotopes
Define isotopes
as different atoms of the same element that have the same number of protons
but different numbers of neutrons
Interpret and use symbols for atoms (e.g. C-12
) and ions (e.g. Cl-35
)
State that isotopes
of the same element have the same chemical properties
because they have the same number of electrons
and therefore the same electronic configuration
Calculate the relative atomic mass (A r
)
of an element from the relative masses
and abundances
of its isotopes
