Physical and Chemical changes

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

Physical and Chemical
Changes

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

Which match has undergone a chemical change and which has undergone the
physical change?

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

Tearing of paper:
Tearing a piece of paper, we can see that the chemical content remains the
same; only one thing that's changed is the size of the paper bits that form as we
tear the paper further. Its physical state has changed. As a result, tearing a piece
of paper is an irreversible physical change.

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

Characteristics of Physical Changes
The physical changes are temporary changes which can be easily reversed
to form the original substance. In such a change, no new substance is
formed.
Thus, we noticed that the important characteristics of physical changes are
as follows:

●No new substance is formed in this change.

●It is a temporary change and is generally reversible.

●A temporary change in colour may take place.

●Very little energy (heat, etc) is either absorbed or evolved.

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

Compare the changes that occur between water and ice, and water and steam,
and explain why these changes happen.

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

PHASE CHANGES

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

Breaking of glass

Breaking of a glass bottle is a physical change because each of the broken
piece of bottle is still a glass and no new substance has been formed. In the
process, only the shape and size of bottle change.

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

Seawater contains salts dissolved in it which
makes it salty. Salt can be obtained from seawater
by the process of evaporation. The salt obtained in
this manner is not pure and its crystals are small.
The shape of the crystals cannot be seen clearly.
Large crystals of pure substances can, however, be
obtained from their solutions by the process of
crystallisation. It is an example of a physical
change. The process of cooling a hot concentrated
solution of a substance to obtain crystals is called
crystallisation.

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

●Blue crystals of copper sulphate contains water of crystallization. These crystals
dehydrate on heating to lose water of crystallisation at a particular temperature and
also change their colour. If the dehydrated copper sulphate solid material is allowed to
cool in air, then it regains blue colour after gaining water molecules from the
atmosphere.

CuSO4 • 5 H20 (bluish) → CuSO4(anhydrous, white) + 5 H2O

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

https://www.youtube.com/watch?v=QdwKhb
tzsug

https://youtu.be/3ZEUAwkJTOI?si=
a76jOaz4yEOjlzNJ

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

Characteristics of Chemical change

-New substances are formed
-The change is permanent and irreversible
-There is a change in the mass of the original substance
-Exchange of energy takes place during a chemical reaction
which means that energy in the form of heat and light may be
released or absorbed,
-The composition of the original substance changes completely.

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

Physical and chemical changes

PHYSICAL CHANGE

CHEMICAL CHANGE

Brings a change in the physical
properties of matter like a change
in shape, size, texture or state.

Causes change in chemical
properties of matter.

No new substance is formed.

A new substance is formed.

Temporary change

Permanent change

It is a reversible change.

Irreversible.

The composition of matter does
not change.

The composition of matter
completely changed.

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

Multiple Choice

A change in which a substance undergoes changes in its physical properties is called _____.

• chemical change

• physical change

• irreversible change

• biological change

Multiple Choice

Browning of an apple after it is cut is an example of ____.

• physical change

• chemical change

• reversible change

• biological change

Multiple Choice

When Magnesium ribbon is burnt in oxygen, the product obtained is ___.

• Magnesium chloride

• Magnesium sulphate

• Magnesium carbide

• Magnesium oxide

Multiple Choice

When Magnesium ribbon is ignited using a candle flame, it burns with a __________.

• sparkling red light

• dull yellow light

• bright green light

• brilliant white light

Multiple Choice

Which of the following is a physical change?

• Rusting of iron

• Melting of wax

• Burning of coal

• Curdling of milk

Multiple Choice

Which of the following is a chemical change?

• Twinkling of stars

• Cutting of fruits

• Cooking of vegetables

• Boling of water

Multiple Choice

A chemical change may involve ____________.

• change in color only

• change in temperature only

• evolution of gas only

• all of the above

Multiple Choice

Which of the following is/are true when milk changes to curd?

(i) Its state is changed from liquid to semi solid

(ii) It changes color

(iii) It changes taste

(iv) The change cannot be reversed.

Choose the correct option from the ones given below:

• (i) and (ii) are correct

• (ii) and (iii) are correct

• (i), (iii) and (iv) are correct

• All are correct

Multiple Choice

A change in which the original substance can be regained by a change in conditions is called _____________.

• a reversible change

• a physical change

• a chemical change

• both (a) and (b)

Multiple Choice

Which of the following is incorrect for a chemical reaction?

• Heat may be given out but never absorbed

• Sound may be produced

• A color change may take place

• A gas may be evolved

Multiple Choice

Which of the following is false?

• When a candle burns, both physical and chemical changes take place.

• Stretching of a rubber band is not a physical change

• Melting of ice is a physical change

• Dissolving common salt in water is not a chemical change

Multiple Choice

The gas that we use in the kitchen is liquefied petroleum gas (LPG). In a cylinder, it exists as a liquid. When it is released from the cylinder it becomes a gas (Change A), and then it burns (Change B). Which of the following is true?

• Process A is a Physical Change

• Process B is a Chemical change

• Both processes A and B are chemical changes

• Both (a) and (b) are True

Multiple Choice

Anaerobic bacteria digest the animal waste and produce biogas (Change A). The gas is burnt as fuel (Change B). The following statements pertain to these changes. Choose the correct one.

• Process A –Physical Change

• Process B- Chemical change

• Both process A and B are chemical changes

• Both process A and B are physical change

Multiple Choice

A physical change is named as such because __________.

• it involves changes in physical properties of a substance

• it is accompanied by a transfer of energy

• it is a reversible process

• it involves the formation of new products

Multiple Choice

Expansion on heating and contraction on cooling of metals are examples of ___________.

• chemical changes

• physical changes

• irreversible changes

• permanent changes

Multiple Choice

Melting and boiling point are ______________ properties of a substance.

• physical

• chemical

• structural

• external

Multiple Choice

“Adding salt to water changes the taste of water.” Which of the following statements is true regarding this change?

• It is a chemical change because a new substance is formed.

• It is a physical change because the original substance can be recovered

• It is a chemical change because the salt cannot be recovered.

• It is a physical change because there is a slight change in colour.

Multiple Choice

Pooja took a candle in a vessel and heated the vessel. Even though the candle did not burn, it changed its shape and state. What kind of change is this?

• Irreversible change

• Physical change

• Chemical change

• Permanent change

Multiple Choice

Which of the following is a physical change?

• Burning of kerosene

• Lighting an electric bulb

• Heating sugar in a pan

• Heating sulphur with iron filings to a red-hot state

Multiple Choice

On the basis of the following diagrams/pictures, answer the question given thereafter. Which of the following changes represent a chemical change?

• Only (i)

• Only (ii)

• (i) and (ii)

• Neither

Open Ended

Is cooking an egg a physical or chemical change? What are the observable characteristics that lead to your conclusion?

Open Ended

When iron reacts with sulfur to form iron sulfide, what type of change occurs? How can you tell that a new substance is formed?

Open Ended

If you freeze orange juice to make popsicles, is it a physical or chemical change? Explain your reasoning.

Open Ended

Assertion: Boiling water leads to a chemical change.
Reason: Boiling changes water from a liquid state to a gaseous state.

a) Both Assertion and Reason are true, and Reason is the correct explanation.
b) Both Assertion and Reason are true, but Reason is not the correct explanation.

c) Assertion is true, but Reason is false.
d) Both Assertion and Reason are false.

Open Ended

An Iron Bar Weighed 664 g. One-eighth of the Iron Turned to Rust. Does rusting change the weight of iron?

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

1.

H – Hydrogen.

2.

He – Helium.

3.

Li – Lithium.

4.

Be – Beryllium.

5.

B – Boron.

6.

C – Carbon.

7.

N – Nitrogen.

8.

O – Oxygen.

9.

F – Fluorine.

10.

Ne – Neon.

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

1.

Na – Sodium.

2.

Mg – Magnesium.

3.

Al – Aluminium.

4.

Si – Silicon.

5.

P – Phosphorus.

6.

S – Sulphur.

7.

Cl – Chlorine.

8.

Ar – Argon.

9.

K – Potassium.

10.

Ca – Calcium.

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

Why is potassium denoted by the letter 'K,' but sodium is

represented by the letter 'Na'?

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

1.The first letter(in capital) of the english name of the element like

Hydrogen-H Oxygen-O
Boron-B Fluorine -F
Carbon-C Iodine-I
Nitrogen-N Phosphorus-P
Sulphur-S

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

2. The first letter along with one more letter of the
english name of an element(when the names of two or
more elements begin with the same letter)

Helium-He Calcium-Ca
Argon-Ar Cobalt-Co
Zinc-Zn Magnesium-Mg
Chlorine-Cl Manganese-Mn
Aluminium-Al
Argon-Ar
Bromine-Br

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

3. One or two letters of the latin name of an element.
Sodium(Natrium)-Na
Potassium(Kalium)-K
Silver(Argentum)-Ag
Mercury(Hydrargyrum)-Hg
Lead(Plumbum)-Pb
Iron(Ferrum)-Fe
Copper(Cuprum)-Cu
Tin(Stannum)-St
Gold(Aurum)-Au

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

Identification of chemical reaction:

Colour Change

A change in color is a sign that a chemical change might be taking place. An
example of a reaction which causes a color change is the rusting of iron. In this
reaction, iron reacts with oxygen in the presences of water. The iron oxide that
forms is an orange/brown color, different to the gray metallic color of the iron.

Gas

If a gas is produced, then a chemical reaction has occurred. A clear sign of
this is bubbles in a liquid. This isn’t to be confused with boiling, as boiling
is a physical change.

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

Temperature Change

A change in temperature, either an increase or decrease, can indicate a
chemical reaction has occurred. When energy is released, the reaction can be
described as exothermic. When energy is taken in, the reaction can be
described as endothermic.

Precipitation

Sometimes when two liquids are combined, a solid can form. This solid is
known as a precipitate and can fall to the bottom or can make the previously
clear liquid cloudy.

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

Noticeable Odor

If there is a noticeable odor after the reaction has occurred, then this could indicate a
chemical change has happened. An example of this is milk turning sour.

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

Create a spider map identifying and illustrating the signs of
a chemical change.

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

1.

Identify the different indicators that a chemical change has occurred and
write them in the titles of the cells.

2.

Illustrate these indicators using a combination of characters, props,
shapes, and scenes.

3.

Write a description of each indicator underneath.

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

A symbol is an abbreviation of the name of an
elements.The symbol of elements have been
derived in three different ways.

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

Arrangement of electrons in different shells(orbits) around
the nucleus of an atom is called its electronic
configuration.
Neil Bohr and Charles Bury proposed a scheme for
distribution of electrons in different shells of an atom
based on the formula 2n² where n denotes the number of
shell

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

K shell,n=1,no. of electrons= 2

Atoms have tendency to have eight electrons in the outermost shell to attain
stability,for which it either gains or loses electron(s). This is called Octet rule

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

https://youtu.be/lVSF2lP4oBA

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

Ion Formation- When an atom loses or gain electron, it develops
either a positive or negative charge because the balance of
positive and negative charges becomes unequal.In this way ions
are formed.

2.Ions are the charged particles formed due to the loss or gain of
one or more electrons by an atom.

3.Ions with a positive charge are called cations. Ions with a
negative charge are called anions.

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

Naming of simple compounds

1. Write down the name of the metal
2. Write down the name of the non-metal but change the ending to “ide.”

1) magnesium 2) oxygen = magnesium oxide
1) sodium 2) chlorine = sodium chloride

Element 1

Element 2

Name of the compound

Copper

Bromine

Silver

Sulfur

Calcium

Oxygen

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

Naming of complex compounds
Many compounds contain more than two elements. Naming them can get
complicated but for those containing two elements plus oxygen the name ending
usually changes to –ate.

Element 1

Element 2

Element 3

Name of the
compound

Nickel

Sulphur

Oxygen

Nickel Sulphate

Magnesium

Nitrogen

Oxygen

Sodium

Nitrogen

Oxygen

Copper

Sulphur

Oxygen

Aluminium

Bromine

Oxygen

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

Molecular Formula of Compounds Criss cross metod

Step 1 - Write symbols and valencies

Sodium Oxide 1+ 2-
Na O

Step 2 - 1+ 2-
Na O

Exchanging valencies

Step 3 - Na2 O1

Molecular formula - Na2O

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

Find the formula of following compounds

Calcium Oxide

Magnesium Nitride

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

Valency of few elements/ions

Cation

Valency/Charge

Anion

Valency/Charge

Sodium
Hydrogen
Magnesium
Calcium
Ammonium
Aluminium

1+
1+
2+
2+
1+
3+

Oxygen
Nitrogen
Chlorine
Sulphate
Nitride
Carbonate

2-
3-
1-
2-
3-
2-

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

Burning of Magnesium ribbon

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

https://youtu.be/hvAbyYJ0vlc- Why Mg is used to make firecrackers?

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

Reaction of Vinegar and Baking soda

https://youtu.be/YGzjAzbdACg?si=-bxG31OIPo9T1VKf

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

https://youtu.be/Vl9A8Iyc_LY?si=fECwUzBPW9o20hK6

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

Copper sulphate and iron

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

Rusting of iron

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

How to prevent rusting?

A.

By coating a layer of oil on iron objects

B.

Galvanisation: The process of depositing thin layer ( or coating) of Zinc on iron
metal.

C.

Electroplating:This is also called as Chrome plating as chromium metal is
resistant to air and moisture.

D.

By applying a few coats of paint over iron metal.

E.

When iron is mixed with carbon, chromium, nickel then stainless steel is
obtained which is a alloy of iron.

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June

©GEAR Foundation 2024-2025 GEAR Innovative International School

GIIS/AY2024-25/XM/Che/G7/June