Atoms•All matter consists of tiny units•Consist of a nucleus in the centre surrounded by electron. Electron move around the nucleus following orbit

Atom is made up of particles that are even smaller called subatomic particles

3 types of subatomic particles which are

Electron move around the nucleus at high speed In neutral atom,

No of protons = No of electron

Subatomic particles Charge

Protons, p Positive charge (+1)

Neutrons, n No charge (0)

Electrons ,e Negative charge (-1)

Proton number and nucleon number

Terms Meaning

Proton Number

The no of protons in an atom

Nucleon Number

The total number of protons + neutrons in an atom

Cl3517

Symbol of element

Nucleon Number•Is always the bigger number•Total no of protons+neutrons

Proton number•Is always the smaller number•Is equal to the no. of electron

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No of neutrons = Nucleon number – Number of protons

Isotope

Atoms Of Different Elements The same number of protons & electrons

are found in atoms of the same element Positive charge & negative charge of an

atom is same (atom is neutral)

ISOTOPE

Atoms of the same element which contain the same no of protons but different number of neutron.

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Isotope

It can also can be defined as atoms of certain elements with the same proton numbers but with different nucleon numbers.

Three important points to define isotopes. Isotopes are different atoms of the

same element. Isotopes have the same number of

protons or same proton numbers. Isotopes have different numbers of

neutrons or nucleon numbers.

Although there are only 115 elements, there are MORE than 1700 ISOTOPES on the earth.

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Hydrogen Isotope

Each isotope is named by INSERTING THE NUCLEON NUMBER AFTER the name of element

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EXERCISE 4.2 a) Complete the table below:

b) Complete the number of subatomic particles for isotopes of chlorine

ATOM NUMBER OF

PROTON

NUMBER OF

ELECTRONS

NUMBER OF

NEUTRONS

V 7 7

W 8 9

X 9 10

ELEMENT

ISOTOPE NUMBER OF

PROTONS

NUMBER OF

ELECTRONS

NUMBER OF

NEUTRONS

CHLORINE

Chlorine-35

Chlorine-37

Cl3517

Cl3717

EXERCISE BOOK

Periodic Table

Periodic Table Elements are arranged in order of

increasing proton number Proton number increases from left to

right and from top to bottom GROUP: Vertical column Elements in same group have similar

chemical properties PERIOD: Horizontal row Chemical and physical properties

gradually changed when crossing periods

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There are 18 groups numbered from 1 to 18 and 7 periods numbered from 1 to 7

VERY REACTIVE METAL (Group 1-alkali metal and Group 2-alkaline earth metal)

HALOGENS (Group 17- non metal) NOBLE (INERT GAS) (Group 18-stable

and unreactive) TRANSITION ELEMENTS (Group 3 to 12) LANTHANIDE SERIES (Period 6) ACTINIDE SERIES (Period 7)

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Locations of metals, non- metals and semi-metals METAL (Elements in Group 1 , 2 ,13

and transition metals) NON-METAL (Elements in group

16 ,17 ,18) SEMI-METAL (Elements between

metal and non metal. Possess certain properties of metal and non-metal)

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PERIODIC TABLE CARD GAME

Importance of periodic table Helps us to study elements in orderly

and systematic approach Help us to know properties of

elements because elements with similar properties are in same group

Help us to predict the properties and uses of an element

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