4-2 Notes

1. 4-2 Notes Organizing the Elements

2. Mendeleev’s Periodic Table • 1869 Russian scientist who discovered a pattern of the elements • Arranged the elements in order of increasing atomic mass (average mass of all the isotopes of an element) • Then he lined them up in groups of similar properties • Developed the first periodic table of elements • Contained 63 elements

3. The Modern Periodic Table • Changed as new elements were discovered • Contains over 100 elements • Arranged in order of increasing atomic number (not atomic mass like Mendeleev’s) • Atomic number = number of protons in an atom of that element • The properties of an element can be predicted from its location on the periodic table

4. The Periodic Table • Elements are organized into rows and columns based on their atomic number.

5. The Periodic Table • Elements are organized into rows and columns based on their atomic number.

6. The Periodic Table • Elements are organized into rows and columns based on their atomic number.

7. Classes of Elements • Open your books to pages 134-135 • Each colored region corresponds to a different class of elements • Metals = blue • Semimetals = yellow • Nonmetals = light green • Inert gases = dark green

8. Periods • Horizontal rows • There are 7 periods on the table, look how they are labeled on the left side of the table • Properties within each period change in a pattern • Notice the lanthanides and actinides have been taken out of the table and placed underneath it • This is to save space and make the table easier to read • Look at the expanded table on page 136

9. Groups • Vertical columns • Aka family • Elements within the same groups have similar characteristics

10. Finding Data on Elements • Each square in the periodic table lists four pieces of information: an element’s atomic number, chemical symbol, name, and atomic mass.

11. Problems: • The atomic number tells how many _________ are in an atom of the element. • Protons

12. Problems: • What is the chemical symbol for lead? • Pb

13. Problems: • How many protons does potassium have? • 19

14. Problems: • What group number is beryllium in? • Group 2

15. Problems: • What period does silver belong to? • Period 5