Page 106 - Innovator's Science-8

chemical bond. In the case of water, every molecule contains 2 atoms of
Science hydrogen and 1 atom of oxygen (a 2:1 ratio). The properties of water are
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very different from either hydrogen or oxygen alone. Similarly, common
Observation
The term ‘compound’ was salt is also a compound made when sodium (a soft metal) combines with
first used by Robert Boyle chlorine (a poisonous gas) in a 1:1 ratio, forming a safe substance we use
in the 17th century. He
explained that every day. While a compound itself cannot be separated into its elements
compounds are formed by physical methods, if it is mixed with something else, like salt dissolved in
when two or more water, the mixture can be separated physically—for example, by
elements chemically
unite in fixed propor ons. evaporation.
Is it possible to separate sodium chloride into its elements by physical
processes? Let us now explore if we can separate the elements in sugar!

Activity-4 Aim: To show that sugar is a compound made Test tube holder
up of carbon, hydrogen, and oxygen.
Experiential Learning
Put a teaspoon of sugar in a boiling tube and Boiling
tube
heat it gently. What do you observe?
When sugar is heated, it first turns brown and Spirit
lamp
then slowly becomes black as it chars. During
this process, ny droplets of water appear near (a) Heating of sugar
the open end of the boiling tube. This water Test tube holder
Water
comes from the sugar itself, not from the air, droplets
because the heat causes the sugar to break Boiling
tube
down, releasing water and leaving behind black Sugar after
heating
carbon, also known as charcoal. This shows that Spirit
sugar is not an element but a compound made lamp
up of three elements—carbon, hydrogen, and (b) Colour of the sugar changes on heating
Science oxygen. When heated, sugar decomposes into Watch glass
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carbon (which stays as the black residue) and
Observation water (which is released as droplets). Charcoal
More than 45 different (carbon)
elements like aluminum,
(c) Charcoal placed on a watch glass
copper, silicon, cobalt,
Heating sugar in a boiling tube
Heating sugar in a boiling tube
lithium, gold and silver
are used to make a
mobile phone– including HOW DO WE USE ELEMENTS, COMPOUNDS, AND MIXTURES?
its screen, ba ery and
other parts. Everything around us is made up of elements, compounds, and mixtures.
The air we breathe is a mixture of several gases such as oxygen, nitrogen,
and carbon dioxide. Water, which all living things need to survive, is a
compound formed from the elements hydrogen and oxygen. Elements like
iron and aluminium are pure substances used to build structures like

bridges, vehicles, and buildings. Understanding these substances is
important because it helps scientists and engineers create new things.

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Science-8