Atomic Theory and Structure The Periodic Table

1. Atomic Theory and StructureThe Periodic Table Discovery of the Atoms and their Properties Periodic Table Trends in the Periodic Table Elements and their Names

2. History of the Atom From ancient Greek times of philosophy to today's technological era of quantum physics, scientists have been mesmerized by what is thought to be the smallest particle - the atom. In Greek, the prefix "a" means "not" and the word "tomos" means cut. Thus, atomos or atom means uncuttable or undividable. 

3. �It all began with� All matter is made up of undividable particles called atoms.  There is a void, which is empty space between atoms.  Atoms are completely solid.  Atoms are homogeneous, with no internal structure.  Atoms vary in: 1)Size 2) Shape 3) Weight

4. �September of 1803�

5. �Dalton�s Research� 1.Chemical elements are made of atoms 2.The atoms of an element are identical in their masses. 3. Atoms of different elements have different masses. 4. Atoms only combine in small, whole number ratios. 5. Atoms can neither be created nor destroyed.

6. �J.J. Thompson� In 1904 JJ Thomas verified the existence of positive particles. He visualized that atoms were positively charged �pudding� and the negative matter �plums� were spread throughout the pudding.

7. ..then came Ernest Rutherford� Having worked under JJ Thomas, Rutherford was very familiar with the study of the atom. Through experiments with radioactive studies he proved that atoms had a nucleus. This became known as the Gold Foil Experiment due to his use of gold foil to reflect the radioactive particles.

8. �Neils Bohr � Bohr built onto Rutherford�s nucleus devising a �Planetary Model�.

9. Pictures of Bohr�s Research

10. Key Definitions of Today�s Atom Proton � positive part of the atom; found in the center of the atom (nucleus) Neutron � neutral (no charge) part of the atom; found in the center of the atom Electron- negative part of the atom; found circling the center of the atom Nucleus � center of the atom; home of the proton and neutron; has the majority of the mass of the atom

11. The Periodic Table The periodic table was organized over the years to provide scientists information about the different elements. Both man-made and natural, the elements are placed in order of things such as atomic mass, atomic number, size and other things.

12. Dmitrii Mendeleev The first periodic table was put together by Mendeleev over 130 years ago. He put the elements in order of relationships of reactivity (how elements react). His table had holes in it that allowed for other elements to be discovered at a later time.

13. Today�s Periodic Table Mendeleev was correct in his holes on his table. Today�s table looks very similar to his table. It lists the elements in order of their atomic number. The first 92 elements have been found in nature. All other elements have been man-made.

14. Parts of the Periodic Table

15. Breaking apart even further Groups of elements � vertical columns of elements on the periodic table Chemical Family � a group of elements that includes the number of the column Period of elements � horizontal row of elements

26. Trends in the Periodic Table When studying the periodic table one can tell many things about an element just by its location on the table. These trends help scientists identify new elements and understand why an element has different properties.

27. Atomic Size Atomic size within a group increases as one moves vertically down the periodic table. Atomic size within a period decreases as one moves horizontally right across the periodic table.

28. Ionization Energy(the energy required to remove an electron from an element) The energy required for elements within a group decreases as one moves vertically down the periodic table. The energy required for elements within a period increases as one moves horizontally right across the periodic table. The most metallic elements (Group IA) have the lowest energies of any elements on the periodic table.

29. Melting Points Melting points of elements increase when one moves horizontally right across the periodic table until about half way across the periodic table. After this point the melting points decrease when moving right across the periodic table. Carbon has the highest melting point of any element (4100 �C)

30. Density of Elements Densities within a group increase as one moves vertically down the periodic table. Densities within a period first increase then decrease when moving horizontally right across the periodic table. The switch occurs near Group VIIIB. Elements with the greatest densities are at the center of Period 6.

31. Gathering Information from the Periodic Table When one looks at a periodic table, there are many letters and numbers that help identify the elements and give way to their characteristics. Understanding these letters and numbers will allow for a better understand of each element.

32. Atomic Mass (Mass Number) The average of all of the masses of the naturally occurring isotopes of an element. The mass number is the rounded atomic mass. It is the number of protons and neutrons found in an atom.

33. Atomic Number The number of protons in the nucleus of an atom

34. Protons, Neutrons, and Electrons # of Protons � same as the atomic number #of Electrons � same as the atomic number and the number of protons #of Neutrons � found by subtracting the atomic number from the mass number

35. Example # of Protons � _______________ #of Electrons � _______________ #of Neutrons � _______________

36. Names and Symbols of Elements Looking at the periodic table reveals the symbols of each element. These symbols provide an easier way to write out each element rather than writing the long word each time. The shortcut in writing was devised based upon the origin of the element�s name. Learning the symbols makes recording the scientific data easier.

37. Common Elements and Their Symbols

38. Common Elements with Unique Symbols