3.1.1 - Atomic Structure
Be able to describe the properties of protons, neutrons and electrons in terms of relative charge and relative mass.
Atoms are made up of smaller, sub-atomic particles. The fundamental sub-atomic particles are protons, neutrons and electrons. The protons and neutrons are held together in the nucleus by strong nuclear binding forces. The electrons exist in regions of space known as the orbitals around the atom.
The properties of the sub-atomic particles are:
Atom: Protons Neutrons Electrons
Relative Mass: 1 1 0
Relative Charge: +1 0 -1
Know that early models of atomic structure predicted that atoms and ions with noble gas electron arrangements should be stable.
The electrons are arranged to energy levels. The lowest energy is the one closest to the nucleus: the first level can hold up to two electrons; the second level can hold up to eight electrons; the third level can hold 18 electrons. The outer energy level holds the electrons that affect bonding and chemical reactivity.
Ions are formed when atoms either lose or gain electrons.
Protons, Neutrons and Electrons
Understand the importance of these particles in the structure of the atom and appreciate that there are various models to illustrate atomic structure.
Ions add a charge to the atom, remember that a positive ion has lost electrons.
Mass Number and Isotopes
Be able to to recall the meaning of mass number (A) and proton number (Z).
The atomic number is the number of protons in the atom (and the number of electrons in a neutral atom), and is represented by the letter Z.
The atomic mass number is represented by the letter A, and is the number of nucleons in…