Study Notes
Periodic trends describe how elements change in properties across the Periodic Table. These trends help predict the behavior and characteristics of elements based on their position.
- Metallic Character — Elements become less metallic from left to right across a period. Example: Sodium is more metallic than chlorine.
- Group Number — Indicates the number of electrons in the outer shell of an element. Example: Group 1 elements have one outer electron.
- Alkali Metals — Group 1 elements with one valence electron, highly reactive. Example: React with water to form hydrogen gas.
- Alkaline Earth Metals — Group 2 elements with two valence electrons, less reactive than alkali metals. Example: Magnesium reacts with water to form hydrogen gas.
- Halogens — Group 7 elements with seven valence electrons, highly reactive non-metals. Example: Chlorine forms ionic compounds with metals.
- Noble Gases — Group 8 elements with full valence shells, very unreactive. Example: Helium is used in balloons due to its low reactivity.
Exam Tips
Key Definitions to Remember
- Metallic character
- Group number
- Alkali metals
- Alkaline earth metals
- Halogens
- Noble gases
Common Confusions
- Confusing metallic and non-metallic character trends
- Misunderstanding the relationship between group number and valence electrons
Typical Exam Questions
- What happens to metallic character across a period? It decreases from left to right.
- How do alkali metals react with water? They produce hydrogen gas and a metal hydroxide.
- Why are noble gases unreactive? They have a full valence shell of electrons.
What Examiners Usually Test
- Understanding of periodic trends and their implications
- Ability to predict element properties based on position in the Periodic Table
- Knowledge of characteristic properties of different groups