Atomic Structure• All Material are ultimately made up of
atoms.
• Atoms are the smallest ‘building block’ of matter.
• Each element has a set number of protons eg. Hydrogen has 1 proton, Helium 2 protons and Gold 79 protons
The total number of protons and neutronsin an atom is called its
mass number.
C12
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The number of protons in an atom is called its
atomic number.
Electron Configuration• The first shell can hold 2 electrons
• The second shell can hold 8 electrons
• The third shell can hold 8 electrons
• The fourth shell can hold 2 electrons
• The electrons always fill up the lowest shell before any other
• In a atom…
Number of Electrons = Number of Protons
– This means atoms are electrically neutral
– If electrons are added or removed then the atom becomes a charged particle we call an ion