1. Organizing the Elements
Chapter 4 Section 2

2. Mendeleev
Russian scientist that discovered a set of patterns that applied to all the elements in 1869

3. Some elements have similar chemical and physical properties

4. Atomic mass is the average mass of all the isotopes of an element

5. He noticed that a pattern of properties appeared when he arranged the elements in order of increasing atomic mass

6. When Mendeleev arranged the 63 known elements by their atomic mass and arranged them into groups with similar properties, he had three blanks, which he correctly assumed were elements not discovered yet, and he even predicted some of their properties.

7. He published the first periodic table in 1869.
A chart of elements showing the repeating pattern of their properties

8. Period is a row in the table

9. Family(group) is a column in the table

10. Table arranged by atomic number today

11. Organization of the Periodic Table
The properties of an element can be predicted from its location of the periodic table.
Arranged by increasing atomic number

12. Periods
Horizontal rows (7) that contain a series of different elements

13. The properties of the elements change as you go from left to right (eg) elements on the left side are highly radioactive metals, less radioactive in the middle, and then the metalloids, followed by the nonmetals on the right.

14. The above pattern is repeated for each of the periods

15. Families
18 vertical columns

16. Consists of elements with similar chemical properties
Note: the actinide and lanthanide series are not part of the families and periods

17. Reading an Element’s Square
Each square includes the element’s atomic number, chemical symbol, name, and atomic mass

18. A symbol is a shorthand way to write the element’s name
A symbol is a shorthand way to write the element’s name. It consists of a capital letter, a Capital letter and a lower case letter, or a Capital letter and two lower case letters

19. Elements names can be in any language, but most are either in Latin, English, or Russian

20. The atomic mass is an average because most elements have isotopes of varying atomic masses

21. How elements form in the sun
The current theory is that all the elements discovered so far originally came from electrons that have escaped from stars.

22. Stars are made up of hydrogen, which is at high temperature and pressure. At this high temperature and pressure, Hydrogen exists as plasma ( a gas like mixture of free electrons and nuclei of atoms that have been stripped of electrons). Plasma has a positive charge, but the since the pressure and temperature is so great the particles do not repel each other.

23. Fusion
When colliding nuclei have enough energy , they can join together.

24. Two small nuclei collide and fuse, forming a nucleus with a higher atomic number. Two larger nuclei then collide and fuse, forming a still larger nuclei and smaller nuclei which are released.