Curriculum
Science — First Preparatory
Unit 1: Matter
0/8
Unit 2: Forces
0/6
Unit 3: Life
0/6
Unit 4: Earth and Space
0/4
Text lesson
The Periodic Table
The Periodic Table
Common mistakes
Common mistakes
- Confusing a period with a group. A period is a horizontal row; a group is a vertical column.
- Forgetting that elements are ordered by atomic number, not by atomic mass.
- Counting electrons in the first or a middle level instead of the outer level when finding the group number.
- Thinking noble gases react easily. In fact they are unreactive.
The Periodic Table · 5 / 6