Structure of Atoms<br />The History and Models of Atoms<br />
Studying Atoms<br />Scientists have been studying atoms since the 1800s. <br />If atoms are too small to be seen, how do w...
Models<br />In science, a model is an idea, a picture, or an object that is built to explain how something else looks or w...
History of the Atom<br />Democritus, a Greek philosopher, first used the term atom (atomos) around 400 BC.<br />John Dalto...
More History of the Atom<br />In 1901 Ernest Rutherford found discovered the nucleus, or center of the atom.<br />In 1917 ...
Atomic Mass Unit<br />Subatomic Particles are so small that a special unit was devised to measure them.<br />This is the a...
Model of an Atom<br />The central part of the atom is called the nucleus.<br />The nucleus contains positively charged pro...
Model of an Atom<br />Electron<br />Proton<br />Neutron<br />
Nucleus<br />The nucleus is where the protons and neutrons are located within the atom.<br />
Atomic Number<br />The atomic number of an atom is the number of protons it has.<br />If an atom has 6 protons, it is carb...
Atomic Number<br />
Practice Number of Protons<br />
Electron Cloud<br />The electron cloud is the region around the nucleus occupied by electrons.<br />Atoms are much, much d...
Electrons<br />Electrons are also arranged in shells.<br />The first shell can hold a maximum of 2 electrons. All other sh...
Valence Electrons<br />The outermost shell of an atom is called the valence shell.<br />
Protons and Electrons<br />In an ATOM the number of electrons should always equal the number of protons.<br />
Isotopes<br />An Isotope is when an atom has a different number of protons and neutrons.<br />Most elements have many diff...
Writing Isotopes<br />To describe an atom, write the name of the atom and then write the total number of protons and neutr...
Isotopes and Mass Number<br />
Practice Isotopes<br />
Abbreviating Mass Number<br />To abbreviate mass number, write the symbol of the atom and then to the upper left write the...
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Structure of atoms10

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Structure of atoms10

  1. 1. Structure of Atoms<br />The History and Models of Atoms<br />
  2. 2. Studying Atoms<br />Scientists have been studying atoms since the 1800s. <br />If atoms are too small to be seen, how do we study them?<br />Scientists use models to study atoms.<br />Sometimes scientists can tell what things look like by studying how they act.<br />Example: Wind<br />
  3. 3. Models<br />In science, a model is an idea, a picture, or an object that is built to explain how something else looks or works.<br />The model might not look exactly like the object it is built to describe, but it helps people understand the way the object acts.<br />
  4. 4. History of the Atom<br />Democritus, a Greek philosopher, first used the term atom (atomos) around 400 BC.<br />John Dalton showed that materials were made of atoms in 1803.<br />In the late 1800s we discovered that the atom has many smaller parts.<br />In the late 1800s, English physicist J. J. Thomson discovered the electron.<br />Dalton<br />Thomson<br />
  5. 5. More History of the Atom<br />In 1901 Ernest Rutherford found discovered the nucleus, or center of the atom.<br />In 1917 Niels Bohr, working as Ernest Rutherford’s student, discovered how electrons orbit the nucleus.<br />His model of the atom is the current base for the modern atomic model. <br />
  6. 6. Atomic Mass Unit<br />Subatomic Particles are so small that a special unit was devised to measure them.<br />This is the atomic mass unit (amu).<br />Atoms are almost entirely empty space.<br />If the nucleus were the size of a basketball, the first electrons would be somewhere near Springfield.<br />
  7. 7. Model of an Atom<br />The central part of the atom is called the nucleus.<br />The nucleus contains positively charged protons that weigh 1 atomic mass unit.<br />The nucleus also contains neutrons that have no charge and weigh 1 atomic mass unit.<br />Electrons are extremely small units of an atom that have a negative charge and move around the atom in orbits.<br />Protons and electrons stay together because they attract each other.<br />+<br />O<br />-<br />
  8. 8. Model of an Atom<br />Electron<br />Proton<br />Neutron<br />
  9. 9. Nucleus<br />The nucleus is where the protons and neutrons are located within the atom.<br />
  10. 10. Atomic Number<br />The atomic number of an atom is the number of protons it has.<br />If an atom has 6 protons, it is carbon.<br />It does not matter what else it has, if it has 6 protons then it is carbon.<br />
  11. 11. Atomic Number<br />
  12. 12. Practice Number of Protons<br />
  13. 13. Electron Cloud<br />The electron cloud is the region around the nucleus occupied by electrons.<br />Atoms are much, much denser near the nucleus.<br />
  14. 14. Electrons<br />Electrons are also arranged in shells.<br />The first shell can hold a maximum of 2 electrons. All other shells can hold up to 8 electrons.<br />
  15. 15. Valence Electrons<br />The outermost shell of an atom is called the valence shell.<br />
  16. 16. Protons and Electrons<br />In an ATOM the number of electrons should always equal the number of protons.<br />
  17. 17. Isotopes<br />An Isotope is when an atom has a different number of protons and neutrons.<br />Most elements have many different isotopes. <br />This makes the nucleus unstable or radioactive in many cases.<br />
  18. 18. Writing Isotopes<br />To describe an atom, write the name of the atom and then write the total number of protons and neutrons that are found in it’s nucleus.<br />The total number of protons and neutrons in the nucleus is called the Mass Number.<br />
  19. 19. Isotopes and Mass Number<br />
  20. 20. Practice Isotopes<br />
  21. 21. Abbreviating Mass Number<br />To abbreviate mass number, write the symbol of the atom and then to the upper left write the mass number and under that, write the atomic number.<br />

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