1. 4.7 Putting the elements in Order (Sec 6.3 pg 193)

2. If you have a group of objects, and you are asked to put them into some sort of order, it can be quite a challenge. NO ORDER ORDER

3. By 1864, chemists had identified 63 unique elements, and were trying to put them into some sort of order. They had already come up with groupings based on properties. For example, they had groups like metals, non-metals, reacts with oxygen, etc.

4. By the mid-1800s, they had discovered that elements had a unique mass when compared to each other. When the elements were listed in order of mass, it was noted that certain patterns repeated periodically. This was called the 'Periodic Law'.

5. A Russian scientist named Mendeleev put the elements into a table with each row increasing in mass, and each column sharing chemical properties. When an element did not fit the pattern he left a gap in his table. This allowed him to predict the properties of undiscovered elements.

6. The predictive power of Mendeleev’s Periodic Table made it extremely useful to chemists. It led to the discovery of many elements as chemists looked for elements to fill the gaps (e.g. argon, neon, germanium, etc).

7. Mendeleev's original periodic table has been revised a number of times. The modern table we use now did not come into existence until 1940.

8. Take a look at the modern Periodic table on page 214. We will eventually be learning about the different groups and families of elements. Let’s do CYU 7.3 #1-5 together

9. Next, copy Figure 3 into your notebook, and label everything except the ‘density at SATP’ Now complete CYU 7.3 #7-10, 13, 14, 16, 17