[CHEM] Chapter 8 - Periodic Table

1 DARRELL ER (COPYRIGHTED) © TOPIC 8: PERIODIC TABLE DARRELL ER (COPYRIGHTED) ©

2 CHAPTER ANALYSIS THE ABOUT TIME EXAM WEIGHTAGE • Content heavy chapter • 3 key concepts • Usually tested along with ‘Atomic Structure’ & ‘Chemical Bonding’ • Highly tested on specifically ‘alkali metals’, ‘halogens’ & ‘noble gases’. • Medium overall weightage • Constitute to 4% of marks for past 5 year papers DARRELL ER (COPYRIGHTED) ©

3 PERIODIC TABLE & TRANSITION METALS ALKALI METALS HALOGENS NOBLE GASES KEY CONCEPT DARRELL ER (COPYRIGHTED) ©

4 PERIODIC TABLE Trend across a period (left to right) - Number of protons increases - Atomic radius decreases - Metallic properties decreases Trends down a group (top to bottom) - Number of protons increases - Number of electron shells increases - Atomic radius increases - Metallic properties remain constant DARRELL ER (COPYRIGHTED) © Horizontal rows are known as periods. (Represent number of electron shells.) Vertical rows are known as groups. (Represent number of valence electrons.) The block of elements between Group II and Group III are called transition metals and they tend to have variable oxidation states.

5 PERIODIC TABLE ION FORMATION Metallic elements will form cations as they lose their valence electrons to form positively charged ions. For example, Group I elements like Sodium (Na) will form Na+ with charge +1. Non-metallic elements will form anions as they gain electrons to form negatively charged ions. For example, Group VII elements like chlorine (CI) will form CI- with charge of –1. DARRELL ER (COPYRIGHTED) © Group I II III IV V VI VII VIII Valence electro ns 1 2 3 4 5 6 7 8 Period II Li Be B C N O F Ne Ion Li+ Be2+ B3+ - N3- O2- F- - Period III Na Mg Al Si P S Cl Ar Ion Na+ Mg2+ Al3+ - P3- S2- Cl- -

6 TRANSITION METALS PHYSICAL PROPERTIES OF TRANSITION METALS Transition metals has high melting points and high densities due to the strong metallic bonds. They are good electrical and thermal conductors. Transition metals also form coloured compounds. CHEMICAL PROPERTIES OF TRANSITION METALS Transition metals has the ability to exhibit multiple oxidation states. Hence, they are frequently used as catalysts. For example, iron is used in the Haber process to produce ammonia, and nickel is used in making margarine through the process of adding hydrogen to vegetable oil (hydrogenation). DARRELL ER (COPYRIGHTED) © TRANSITION METALS Transition metals are found in between the Group II and Group III elements in the periodic table.

7 ALKALI METALS DARRELL ER (COPYRIGHTED) © GROUP I: ALKALI METALS Group I elements are called alkali metals as they reac