Topic C1 Atoms and elements

• Atoms


  Extremely small particles that make up all matter
• There are about 400,000,000,000,000,000,000 atoms
• Atoms


  • Contain protons, neutrons and electrons
• An atom has about 10^23 particles (there's 1x10^23 of them)
• Fundamental particles in an atom

  • Protons
  • Neutrons
  • Electrons
• Elements


  Substances made up of atoms that all have the same number of protons in their nucleus
• The maximum number of protons an element can have is 118
• Atomic number


  The number of protons in the nucleus of an atom
• The atomic number decides what type of atom it is
• Atoms of the same element have the same number of protons
• Atoms of different elements have different numbers of protons
• Atomic symbols


  One or two letter symbols that represent atoms of each element
• Atomic symbols


  • C-carbon
  • O-oxygen
  • Na-sodium
  • Mg-magnesium
  • Fe-iron
• Isotopes


  Atoms with the same number of protons but different number of neutrons
• Isotopes have the same atomic number but different mass numbers
• Carbon-12 and carbon-13 are isotopes of carbon
• Electron


  A negatively charged particle in an atom
• Atoms are overall neutral because they have the same number of protons and electrons
• Atomic number


  The number of protons in an atom
• Mass number


  The number of protons plus the number of neutrons in an atom
• Atoms have no overall charge because the positive charge of the protons is balanced by the negative charge of the electrons
• Relative atomic mass


  The average mass of the isotopes of an element, weighted by their abundance
• Calculating relative atomic mass

  Sum of (isotope abundance x isotope mass number) / sum of abundances of all isotopes
• An ion has a different number of electrons than protons, giving it an overall charge