Page 87 - Innovator's Science-8

7 Particulate Nature

of Matter

Intended Learning Outcomes
What Decides Different States of Ma er? Solid State
Gaseous State How Does the Interpar cle
How Par cles Move in Different States Spacing Differ in the Three
of Ma er? States of Ma er?

Stepping Stones

1. Why can water hold the form of hands when contained, but not keep it a er
being released?
2. Why does a balloon gain weight when filled with air, even though air is not
visible?

Matter is anything that has mass and occupies space. The observable world
is composed of solids, liquids, and gases—particles so small that they
a.
cannot be seen even under an ordinary microscope. These particles are
always in motion and are held together by forces of attraction, with the

extent of movement and space between them determining if the matter
b. appears as a solid, liquid, or gas.
Pebbles, stones, and sand found on riverbanks or beaches originally come

from larger rocks in the mountains. Over time, the rocks in the mountains
break down because of weathering and erosion. Weathering causes the
c.
rocks to become weaker and break apart into smaller pieces, while erosion

means that rivers pick up these pieces and carry them along. As the river
flows, it grinds these fragments against each other breaking them further
into pebbles, sand, and fine clay. The river then carries these small pieces
d. from the mountains all the way to the plains, where they are left behind on
riverbanks and beaches. Over time, all the pebbles and sand seen along
(a) A stick of chalk;
(b) The chalk stick rivers and beaches are the result of this long, natural process of breaking
broken into two pieces; down and transporting rock.
(c) A piece of chalk
ground into fine powder; As you know changes are around us. These changes are called Physical
(d) A close-up view of change and Chemical change. Have you ever grinding chalk? Is grinding
chalk powder under a
magnifying glass chalk a physical change or a chemical change?
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Science-8