From Atoms to Materials

Extension Reactivity of Groups I and II elements increases down the group. Trends in other groups may not be the same. Lithium reacts mildly with water. In Experiment 13.3B , we see that calcium and magnesium react with dilute hydrochloric acid at different rates. Generally speaking, elements in the same group tend to have similar chemical properties, but their reactivity may vary. Lets see the reactivity of three Group I elements with water as an example: Unifying concept You have seen how elements are organized in groups and in periods. This shows a systematic way to organize the elements. Potassium reacts very vigorously with water. It burns with a flame. It moves very quickly on the water surface with a louder hissing sound. Sodium reacts vigorously with water. It burns with a flame, and moves on the water surface with a hissing sound. Elements in the same group have similar chemical properties, but they may have different reactivity. Lithium Sodium Potassium Which of these elements is the most reactive? Experiment 13.3B 2. Write a word equation for: (a) the reaction between magnesium and dilute hydrochloric acid; (b) the reaction between calcium and dilute hydrochloric acid. 40 © United Prime Educational Publishing (HK) Limited 2024 All rights reserved; no part of this publication may be reproduced, photocopied, recorded or otherwise, without the prior written permission of the Publisher. Sample