MATTER

Learning OutcomeLearning OutcomeAt the end of this topic, students should be At the end of this topic, students should be able :able : (a) (a) Identify and describe proton, electron and neutron as subatomic particle. as subatomic particle.

(b) (b) Define proton number, Z, nucleon proton number, Z, nucleon number, A and isotope. number, A and isotope. Write isotope notation.

INTRODUCTION• Matter

Anything that occupies space and has mass.

e.g air, water, animals, trees, atoms, …..

• All matter consist of tiny particles called atoms

Objective:At the end of the lesson, you should be able to:1) Identify and describe protons, electrons and neutrons as sub-atomic particles

TOPIC 1: MATTER SUB TOPIC: Atoms and Molecules

This page will revises the simple ideas about atomic structure that you have come across in an introductory chemistry course (i.e. SPM). You need to be confident

about this before you go on to the more difficult ideas about atom.

THE SUB-ATOMIC PARTICLES

An atom is the smallest unit of a chemical element/compound. In an atom, there are three subatomic particles:

- Proton (p)- Neutron (n)

Electron (e)

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Packed in a small nucleus

Move rapidly around the nucleus of an atom

Modern Model of the Atom

• Electrons move around the region of the atom.

-

-

electron

nucleus

Proton

( positive charge)++

Neutron (neutral)

Objective:At the end of the lesson, you should be able to:2) Define proton number, nucleon number and isotopes

TOPIC 1: MATTER SUB TOPIC: Atoms and Molecules

XAZ

Atomic symbol

Nucleon number or mass number

Proton number or atomic number

Proton no. Nucleon no. Isotopes

Pre-test Example ExercisePast yearQuestion

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Objective:At the end of the lesson, you should be able to:2) Define proton number, nucleon number and isotopes

TOPIC 1: MATTER SUB TOPIC: Atoms and Molecules

Proton no. Nucleon no. Isotopes

XAZ

Atomic symbol

Nucleon number or mass number

Proton number or atomic number

Pre-test Example ExercisePast yearQuestion

Proton number (Z) is the number of protons in the nucleus of each atom of an element.

Also known as atomic numberIn a neutral atom, the number of protons is

equal to the number of electrons.

Proton no.

Objective:At the end of the lesson, you should be able to:2) Define proton number, nucleon number and isotopes

TOPIC 1: MATTER SUB TOPIC: Atoms and Molecules

Proton no. Nucleon no. Isotopes

XAZ

Atomic symbol

Nucleon number or mass number

Proton number or atomic number

Pre-test Example ExercisePast yearQuestion

Nucleon number (A) is the total number of neutrons and protons present in the nucleus of an atom of an element.

Also known as mass number

Nucleon no.

Objective:At the end of the lesson, you should be able to:2) Define proton number, nucleon number and isotopes

TOPIC 1: MATTER SUB TOPIC: Atoms and Molecules

Proton no. Nucleon no. Isotopes

XAZ

Atomic symbol

Nucleon number or mass number

Proton number or atomic number

Pre-test Example ExercisePast yearQuestion

Isotopes, atoms that have the same proton number but different nucleon number.

i.e. Hydrogen has three isotopes

H H H11

21

31

Isotopes

Objective:At the end of the lesson, you should be able to:2) Define proton number, nucleon number and isotopes

TOPIC 1: MATTER SUB TOPIC: Atoms and Molecules

XAZ

Atomic symbol

Nucleon number or mass number

Proton number or atomic number

Proton no. Nucleon no. Isotopes

Pre-test Example ExercisePast yearQuestion

Nucleon number = proton no. + no. of neutrons.So, the number of neutrons is equal to the different between the nucleon no. & the proton no. or ( A-Z).

Ex. Nucleon no. of fluorine is 19 & proton no. is 9. Thus, the no. of neutrons in fluorine is 19 – 9 = 10.Note: proton no., nucleon no. & no. of neutrons all must be positive integers (whole numbers)

Nucleon number or mass number

Objective:At the end of the lesson, you should be able to:2) Define proton number, nucleon number and isotopes

TOPIC 1: MATTER SUB TOPIC: Atoms and Molecules

XAZ

Atomic symbol

Nucleon number or mass number

Proton number or atomic number

Proton no. Nucleon no. Isotopes

Pre-test Example ExercisePast yearQuestion

In a neutral atom the no. of protons is equal to the no. of electrons, so the proton no. also indicates the

no. of electrons present in the atom.

For example, the proton no. of nitrogen is 7. This means that each neutral nitrogen atom has 7

protons and 7 electrons.

Proton number or atomic number

Objective:At the end of the lesson, you should be able to:2) Define proton number, nucleon number and isotopes

TOPIC 1: MATTER SUB TOPIC: Atoms and Molecules

XAZ

Atomic symbol

Nucleon number or mass number

Proton number or atomic number

Proton no. Nucleon no. Isotopes

Pre-test Example ExercisePast yearQuestion

The X represent of atom of an element. For example atom of uranium with nucleon numbers of 235 and proton numbers of 92. So the uranium can

be denoted as:-

U235

92

Atomic symbol

Ex:

Number of protons = proton number= 13

Number of neutrons = nucleon number – proton number= 27 - 13= 14

Number of electron = proton number – charge carried by species= 13 – ( +3)= 10

Q: determine the number of proton, neutron and electron in the following species.

solution

Number of protons = proton number= 38

Number of neutrons = nucleon number – proton number= 90 – 38= 52

Number of electron = proton number (species is neutral)= 38

Sr90

38

Sr

Number of protons = proton number= 17

Number of neutrons = nucleon number – proton number= 35 – 17= 18

Number of electron = proton number – charge carried by species

= 17 – (-1)= 18

3517 Cl-

Objective:At the end of the lesson, you should be able to:2) Define proton number, nucleon number and isotopes

TOPIC 1: MATTER SUB TOPIC: Atoms and Molecules

1. State the sub-atomic particles of an atom?

2. Define proton numbers and nucleon numbers?

3. What is isotopes? Use hydrogen as an example.

ANSWER

1. Protons, electrons & neutrons

2. Proton numbers = number of protons in the nucleus of an atom Nucleon numbers = total no. of protons & neutrons in atom

3. Isotopes = atoms that have the same no. of protons but have different nucleon numbers.

Objective:At the end of the lesson, you should be able to:2) Define proton number, nucleon number and isotopes

TOPIC 1: MATTER SUB TOPIC: Atoms and Molecules

1. Give the number of protons, neutrons and electrons in each of the following species:

(a) (b) (c)

ANSWER

* Recall that the superscript denotes nucleon number & the subscript denotes proton number.

(a) Proton number = 8, so there are 8 protons. Nucleon number = 17, so the number of neutrons is 17-8 = 9. The number of electrons is the same as the number of protons, that is 8.

(b) Proton numbers = 80, so there are 80 protons. Nucleon number = 199, so the number of neutrons is 199-80 = 119. The number of electrons = 80.

(c) Number of protons = 80. Number of neutrons, 200-80 = 120. Number of electrons = 80.

Hg HgO17

8

199

80

200

80

Objective:At the end of the lesson, you should be able to:2) Define proton number, nucleon number and isotopes

TOPIC 1: MATTER SUB TOPIC: Atoms and Molecules

1. Isotopes of an element are having

A the same nuclear charge

B similar physical properties

C the same number of neutrons

D the same relative abundance

2. All the following statements are true EXCEPT

A Nucleus is the positively charged centre of an atom

B Protons number indicates the number of protons in an atom

C Isotopes are atoms of the same element but with different nucleon number

D Nucleon number is the total number of electrons and protons in an atom

ans

Objective:At the end of the lesson, you should be able to:2) Define proton number, nucleon number and isotopes

TOPIC 1: MATTER SUB TOPIC: Atoms and Molecules

1. Isotopes of an element are having

A the same nuclear charge

B similar physical properties

C the same number of neutrons

D the same relative abundance

2. All the following statements are true EXCEPT

A Nucleus is the positively charged centre of an atom

B Protons number indicates the number of protons in an atom

C Isotopes are atoms of the same element but with different nucleon number

D Nucleon number is the total number of electrons and protons in an atom

next

Objective:At the end of the lesson, you should be able to:2) Define proton number, nucleon number and isotopes

TOPIC 1: MATTER SUB TOPIC: Atoms and Molecules

3. Which of the following is a pair of isotopes?

A 13858J and 138

60K

B 7432L and 75

33M

C 8336N and 84

36O

D 23592P and 239

94Q

4. Which of the following species has 24 neutrons?

A 24Mg

B 45Sc

C 51V

D 52Cr

ans

Objective:At the end of the lesson, you should be able to:2) Define proton number, nucleon number and isotopes

TOPIC 1: MATTER SUB TOPIC: Atoms and Molecules

3. Which of the following is a pair of isotopes?

A 13858J and 138

60K

B 7432L and 75

33M

C 8336N and 84

36O

D 23592P and 239

94Q

4. Which of the following species has 24 neutrons?

A 24Mg

B 45Sc

C 51V

D 52Cr

next

Objective:At the end of the lesson, you should be able to:2) Define proton number, nucleon number and isotopes

TOPIC 1: MATTER SUB TOPIC: Atoms and Molecules

WELL DONE!WELL DONE!Try some past paper questionsTry some past paper questions