Shajara Preparatory School E. Lessons

Shajara Preparatory SchoolE. Lessons

Structure of matter

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Grade Eight (A)

Objectives: .To identify structure of atom.

. To identify atomic number of an element.

. To identify mass number of an atom.

. To identify ions and their different types.

. To identify molecule.


Structure of matter

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Grade Eight (A)

Structure of matter

What is Atom

Parts of atom

Particles of atom

Mass number & atomic number

What is ion

How is the ion form

Table of

contents


Structure of matter


Grade Eight (A)

Structure of matter

Atom Ion Molecule


Matter


Matter is made up of tiny particles called atom.The atom has a spherical shape.

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Inside Atom


Atom is made up of the nucleus at the center surrounded by electronic cloud.

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Sub-atomic Particles


- The nucleus: contains two types of particles: - Protons : ( positively charged ) - Neutrons: ( non charged )

- The electron cloud : it surround the nucleus and it contain one type of particles: - Electrons ( negatively charged )

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Sub-atomic Particles


Sub- atomic particles

Symbol Electric charge Location

Protons P + Inside nucleus

Neutrons n no charge Inside nucleus

Electrons _ Move around nucleuse

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Electric Charge of Atom


- In an atom; the number of positive charges ( protons ) is equal to the number of negative charges ( electrons).

This makes the atom electrically neutral

7 (+) charges and 7 (-) charges 8 (+) charges and 8 (-) charges

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Atomic Symbol


An atom can be represented by its atomic symbol:

Where X is the chemical symbol of the element. Z is the atomic number. A is the mass number.

XAZ

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Atomic number


Atomic number= number of protons Z=P

For example, The element carbon has 6 protons in its nucleus.Then, Its atomic number Z=6.

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Mass number


Mass number ( A ) = number of protons + number of neutrons A= p +n For example, in the above figure;

The first carbon atom has 6 protons and 6 neutrons in its nucleus. Then its mass number A= 12The second carbon atom has 6 protons and 8 neutrons in its nucleus. Then its mass number A=14

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Identity of element


Each chemical element is identified by its atomic number (Z) or number of protons

Protons=6Atomic number =6Carbon element

Protons=7Atomic number =7Nitrogen element

Protons=8Atomic number =8Oxygenelement

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Ions


The ion is an atom or group of atoms, that carry a positive or negative charge.

The adjacent figure shows molecular models representing some common ions like:

K+ , Na+, Cl- , Cu2+ , F- , Ca2+ , 23CO

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How is the ion formed?


When an atom lose or gain electrons, it becomes an ion. when an atom loses electron, it attains a positive charge( x+ ) and is called cation.

Lithium atom loses 1 electron and becomes lithium ion. Li – 1 e Li+

Lithium atom3 electrons

Lithium ion2 electrons

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Ions


when an atom gains electrons, it attains a negative charge (X- )

and it called anion.

e

Fluorine atom gains 1 electron and becomes fluorine ion. F – 1 F-

Fluorine atom9 electrons

Fluorine ion10 electrons

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Cations and Anions

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Ions can be classified according to its electric charge as cations or anions. Cations Anions

H+ HO-

O2-

Mg2+ F-

Positively charged ions Negatively charged ions

4NH

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Mono- and Poly- atomic ions

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Ions can be classified according to the number of atoms

contained as mono-atomic or poly-atomic ions. Mono-atomic ions Poly-atomic ions

H+ HO-

O2-

Al3+

Made up of only one atom Made up of many atoms

24SO4NH


Molecules

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A molecule is neutral group of atoms that act as a unit .

Example:• carbon dioxide molecule .• water molecule.• methane molecule. Water molecule

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Practice


Grade Eight (A)

Atoms, molecules , and ions are the buildings blocks of elements and compounds. The table below shows models of different particles:

Oxide Ammonia Dihydrogen Hydronium Water Name of particle

Model

elements

Number of atoms

Electric charge

Nature of particles

+ - Coding

Hydrogen

Oxygen

Nitrogen


Structure of Matter


Grade Eight (A) Students

Prepared by:Firas Sami Al Haj Moussa

Wissam Saddiq Basel Fares Ahmad manasri Hassan shawky

Supervised by:T. Wissam Abdallah

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Shajara Preparatory School E. Lessons