SC3 - Atomic Structure

SC3 - Atomic Structure

1. Structure of an atom

   • 1803 - Dalton - Solid atom model: all atoms of an element are identical; different elements have different atoms
   • 1897 - Thomson - Discovers electron
   • 1904 - Thomson - Plum pudding model: atoms are spheres of positive charge with negative electrons dotted around inside
   • 1911 - Rutherford - Solar system model: atoms have positive nucleus surrounded by negative electrons in orbit
   • 1913 - Bohr - Electron shell model: electrons occupy shells or energy levels around the nucleus
   • 1918 - Rutherford - discovers proton
   • 1932 - Chadwick - discovers neutron
   • a nucleus containing protons and neutrons surrounded by electron shells (strucutre of an atom)
   • Relative masses proton: 1 neutron: 1 electron: 1/1836
   • Relative charges proton: +1 neutron: 0 electron: -1
   • atoms have equal numbers of protons and electrons. they have equal numbers of positive and negative charges and so are neutral overall. electrons have very little mass compared with protons and neutrons. Most of the mass of an atom is concentrated in its nucleus
   • the nucleus of an atom is very small compared to the overall size of the atom

2. Isotopes

   • (Isotopes) different atoms of the same element containing the same number of protons but different number of neutrons in their nuclei
   • Number of Protons = Atomic Number
   • Number of Electrons = Number of Protons = Atomic Number
   • Number of Neutrons = Mass Number - Atomic Number
   • The existence of isotopes results in relative atomic masses of some elements not being whole numbers: relative atomic mass is an average of all the isotopes of an element
     • (https://www.youtube.com/watch?v=SdhLTfma_Eg) How to calculate the Ar (Relative Atomic Mass)

3. Atomic Mass & Number

   • most of the mass of an atom is concentrated in the nucleus
   • mass number of an atom
     • total number of protons and neutrons in the nucleus of an atom
   • atoms of a given element have the same number of protons in the nucleus ad that is the number which is unique to that element
   • Isotopes

4. Structure of an atom

   • 1803 - Dalton - Solid atom model: all atoms of an element are identical; different elements have different atoms
   • 1897 - Thomson - Discovers electron
   • 1904 - Thomson - Plum pudding model: atoms are spheres of positive charge with negative electrons dotted around inside
   • 1911 - Rutherford - Solar system model: atoms have positive nucleus surrounded by negative electrons in orbit
   • 1913 - Bohr - Electron shell model: electrons occupy shells or energy levels around the nucleus
   • 1918 - Rutherford - discovers proton
   • 1932 - Chadwick - discovers neutron
   • a nucleus containing protons and neutrons surrounded by electron shells (strucutre of an atom)
   • Relative masses proton: 1 neutron: 1 electron: 1/1836
   • Relative charges proton: +1 neutron: 0 electron: -1
   • atoms have equal numbers of protons and electrons. they have equal numbers of positive and negative charges and so are neutral overall. electrons have very little mass compared with protons and neutrons. Most of the mass of an atom is concentrated in its nucleus
   • the nucleus of an atom is very small compared to the overall size of the atom

5. Isotopes

   • (isotopes) different atoms of the same element containing the same number of protons but different number of neutrons in their nuclei
   • The existence of isotopes results in relative atomic masses of some elements not being whole numbers: relative atomic mass is an average of all the isotopes of an element
   • (https://www.youtube.com/watch?v=SdhLTfma_Eg) How to calculate the Ar (Relative Atomic Mass)

6. Atomic and Mass Number

   • most of the mass of an atom is concentrated in the nucleus
   • mass number of an atom
     • total number of protons and neutrons in the nucleus of an atom
   • atoms of a given element have the same number of protons in the nucleus and that is the number which is unique to that element
   • Isotopes

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