Bridge to Success Chemistry 3 , livre ebook

pages

English

Ebooks

2015

Écrit par
Alebaweh Sinju Fidelis , Metuge Johnathan Alunge , KumKwe Emmanuel , Jensco Azeh Santos , Chingenyim Valentine Akaagho , Ndifor Florence

Publié par
NMI Education

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pages

English

Ebooks

2015

Lire un extrait

Obtenez un accès à la bibliothèque pour le consulter en ligne En savoir plus

Publié par

NMI Education

Date de parution

01 janvier 2015

Nombre de lectures

EAN13

9789956580406

Langue

English

Poids de l'ouvrage

34 Mo

In the teaching and learning process, learners are expected to have acquired the basic concepts and principles in various subjects taught at the different levels of school. Bridge to Success Chemistry is a learning programme that has the objective of enhancing the acquisition of the required basic competencies in various subject areas. The immediate goal of the programme is to provide a quick summary of key concepts and principles with a lot of practice exercises to help the learner to pass their class and level exams with high grades. The series is innovative and tailored to the school curriculum so that it serves as a good supplementary tool to the core textbook.

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Publié par

NMI Education

Date de parution

01 janvier 2015

Nombre de lectures

EAN13

9789956580406

Langue

English

Poids de l'ouvrage

34 Mo

STUDY&REVISIONGUIDEFORCHEMISTRY

F3 ORM

Alebaweh Sinju Fidelis Metuge Johnathan Alunge KumKwe Emmanuel Jensco Azeh Santos Chingenyim Valentine Akaagho Ndifor Florence

All rights reserved. No reproduction or transmission of this publication without written permission from the publisher and author. The author asserts his right to be identified as the author of this work in accordance with the copyright law.

First edition 2015 © Nmi Education P.O. Box 31267 Yaounde - Cameroon Email: frontdesk@nmieducation.org Website: www.nmieducation.org

Project Manager: Mela Fokam Gisèle Épouse NGADEHI Editorial Assistant : Makowo Momo Solange Typesetter: ABONGHEN Brigitte Cover designer: ABONGHEN Brigitte Illustration: Nmi Education

ISBN: 9956-580-40-6

P REFACE This chemistry study aid is to equip you with skills to better prepare for your examinations. It is well understood that the best method of preparing for an examination involves the study of suitable examination-type questions. The study aid contains the following question types: Multiple Choice Questions (MCQs), Structured Questions and Essay Questions. The questions cover all the topics in the teaching syllabus for this level.

Each topic starts with the 'Learning Points' as a recall to the key concepts and principles for the topic. This is followed by worked examples and then other study questions. The study questions are intended to serve as a self-test. The answers to the study questions appear at the end of each topic. Before attempting to answer them, it is important that you revise the topic thoroughly. Write out your answer completely before cross-checking with the answer sheet. This study aid serves both as a text and a work book.

T C ABLE OF ONTENT

TOPIC 1: Atomic Structure and Periodic Table

TOPIC 2: Chemical combination

TOPIC 3:chemistry of acids and bases The

TOPIC 4:compoundsof the elements and some of their Chemistry

T 1 OPIC

ATOMIC STRUCTURE AND PERIODIC TABLE Atomic structure

LEARNING POINTS

1.1The Atomic Structure There are quite a few different (and equally useful) models of the atom- but chemists tend to like thisnuclear modelbest. You can use it to explain pretty much the whole of chemistry….which is nice.

Shell or orbit

The Nucleus

·It’s in the middle of the atom; ·It contains protons and neutrons; ·It has a positive charge because of the protons; ·Almost the whole mass of the atom is concentrated in the nucleus; ·But size-wise its tiny compared to the rest of the atom. The Electrons ·Move around the nucleus; ·They’re negatively charged; ·They’re tiny, but they cover a lot of space; ·The volume of their orbit determines how big the atom is; ·They have virtually no mass; ·They occupy shells around the nucleus; ·These shells explain the whole of chemistry.

Each type of these sub-atomic particles has its own physical properties which are explained in this table:

Particle Proton Neutron Electron

Symbol p n e

Mass 1 atomic mass uni (amu) 1 atomic mass unit (amu) 1/1840 (Negligible)

Charge +1 no charge -1

Location in an atom Nucleus Nucleus Shell or orbit

·Protons are heavy and positively charged ·Neutrons are heavy and neutral ·Electrons are tiny and negatively charged The mass of the sub-atomic particles is in atomic mass unit (AMU). This is because they are so light that they can't be measured in grams.

Number of protons Equals Number of electrons – Neutral atoms have no charge overall. - The charge on the electrons is the same size as the charge of the protons but opposite. - This means the number of protons always equals the number of electrons in a neutral atom only. - If electrons are added or removed, the atom becomes charged and is then an ion. NB: An ion is an atom or a group of atoms with an electric charge.

Atomic Number and Mass Number Describe an Atom There are two numbers given to each type of atom: -Atomic/Proton Number:It is the number of protons in an atom. And since an atom has an equal number of protons and electrons, it is the number of electrons in the atom too. -Mass/Nucleon Number:It is the number of protons + number of neutrons in the nucleus of an atom. It is called mass number because its value is also mass of the atom. lnumber of protons, and the mass number is the number of protons and neutrons,the atomic number is the If then subtracting the proton number from the mass number will give you the number of neutrons in the atom. l When represent the atom of an element, we give it a symbol of one or two letters where we the first letter is always in capitals and the second one is in lowercase. lmass number goes above the symbol and the atomic number goes below the symbol. The The Mass Number 23 (Total number of protons and Neutrons) (Number of protons)NaExample: The Atomic Number 11

·The mass (nucleon) number is always the biggest number. It tells you the relative mass of the atom. ·The mass number tends to be roughly double the proton number; which means there's about the same number of protons and neutrons in any nucleus. ·The atomic number also gives you the number of electrons.

1.2 The Electronic Configuration of Atoms Electron Shell Rules - Electrons are arranged in energy shells or energy levels. - The lowest energy levels are always filled first- these are the ones closest to the nucleus. i

-But each energy shell can hold up to a certain amount of electrons. st * 1 energy shell holds up to 2 electrons, nd * 2 energy shell holds up to 8 electrons, rd * 3 energy shell holds up to 18 electrons, but stable with only 8 electrons.

rd th If an atom has its 3 energy shell holding 8 electrons and receives 2 more, they go to the 4 energy shell. If rd further 10 electrons are received, they go to the 3 energy shell making it saturated with 18 electrons

?are much stable when they have full electron shells – like the noble gases in Group VIII or 0.Atoms e.g. Neon, Argon, etc. ?In most atoms, the outer shell is not full and this makes the atoms want to react. e.g. Sodium, Chlorine. You need to know the electronic configurations for the first twenty elements. Valence electrons are the electrons in the outermost energy shell. The Isotope: - Some elements have different versions of their atoms. These versions are called isotopes. Isotopes of the same elements have the same number of protons, but different number of neutrons. Chlorine for example has two isotopes, Chlorine-35 and Chlorine-37. Isotopes of the same elements show the same chemical properties because of some number of electrons but only their masses differ, as a result of having a different number of neutrons. - There are two kinds of isotopes, stable and unstable ones. Unstable ones have a lot of neutrons, and they are radioactive. They are called radioactive isotopes. A very popular pair of isotopes are carbon-12 and carbon-14, used for carbon dating Carbon-12Carbon-14 14 126 proCtons6 proCtons6 6 6 electrons 6 electrons 8 Neutrons . 6 Neutrons 1.3 Isotopy - Isotopy is a phenomenon whereby atoms of the same element have the same atomic number but different mass numbers. This is due to the differences in the number of neutrons present in these atoms.

Calculating the Relative Atomic Mass (Ar): The relative atomic mass of an element is the average mass of all its isotopes compared to one-twelfth (1/12) the mass of an atom of Carbon-12. The rule of calculating the Arof an element is:

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