Wednesday, October 27

1. Wednesday, October 27

2. Warm-up • What are the numbers of protons and neutrons for strontium and Yttrium? • Use your notes and write down all six periodic trends that we discuss yesterday.

3. Warm-up • What are the numbers of protons and neutrons for strontium and Yttrium?Useyour notes and write down all six periodic trends that we discuss yesterday.

4. A group of elements on the same row are called period. • So as you go across a period from the left to the right the atomic number (protons) and atomic mass increases.

5. Elements that are in the same vertical column (up and down) are called a group or family. • A group of elements all have the same number of valence electrons.

6. Trends that we’ve discussed • Going left to right the atomic number increases • Example: Going right across a period the atomic number increases • Going left to right the atomic mass increases • Going right across a period the atomic mass increases • Going right to left the atomic size increases • Going left across a period the atomic size increase • Going top to bottom the atomic size increases • Going down a group the atomic size increases • Going left to right the number of valence electrons increases • Going right across a period the valence electrons increases • Going top to bottom the number of valence electrons stays the same • Elements of a group the valence electrons stays the same

7. Essential Idea • What physical property distinguishes one atom from another? • The number of protons; the atomic number