Which part of an atom has a relative mass of 1 and a relative charge of 0 ?

2.2.1. Describe the structure of the atom as a central nucleus containing neutrons and protons surrounded by electrons in shells

2.2.2. State the relative charges and relative masses of a proton, a neutron and an electron

2.2.3. Define proton number / atomic number as the number of protons in the nucleus of an atom

2.2.4. Define mass number / nucleon number as the total number of protons and neutrons in the nucleus of an atom

2.2.5. Determine the electronic configuration of elements and their ions with proton number 1 to 20, e.g. 2,8,3

2.2.6.1. Group VIII noble gases have a full outer shell

2.2.6.2. the number of outer shell electrons is equal to the group number in Groups I to VII

2.2.6.3. the number of occupied electron shells is equal to the period number

2.3.1. Define isotopes as different atoms of the same element that have the same number of protons but different numbers of neutrons

2.3.2. Interpret and use symbols for atoms, $\text { e.g. }{ }_{6}^{12} \mathrm{C} \text {, and ions, e.g. }{ }_{17}^{35} \mathrm{Cl}$

2.3.3. 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

2.3.4. Calculate the relative atomic mass of an element from the relative masses and abundances of its isotopes