## Nature’s Density

What is
Density? Density is how much ‘stuff’ is packed into a particular area.

For
example, if we have 13 balls in a box and we have the same box with 27
identical balls inside it. We say the box with 27 balls has higher density than
the box with 13 balls.

Density
is a fundamental property of matter. Density is defined as mass divided by unit
volume. It is measured in grams per cubic centimeter or kilograms per cubic
meter. The Greek letter rho, is the symbol for density.

Density,
ρ = Mass ÷ Volume

So,
two liquids can take up the same amount of space(volume) but can have
completely different masses. If liquid A has a higher mass, MORE of that liquid
is in that space and therefore is denser. If liquid B has a lower mass, LESS of
that liquid is in that same space and is therefore less dense than liquid A.

All
liquids in your tower have similar volumes but they have different densities.
What does that mean? That means that each liquid has a different amount of mass
in that volume. The liquids with the highest density are at the bottom, and the
ones with the lower density are on top of each other. So, which of the liquids
is most dense? And which is least dense?

## Bag Stab & Polymerization

A plastic bag is made of polymers, long chains of individual molecules called monomers. When a sharp pencil pierces the bag the polymer chains separate without breaking. The chains of molecules then squeeze tightly around the pencil creating a seal that prevents it from leaking.

Polymers
find use in our everyday life, from water bottles and Tupperware to tires for
automobiles. The word polymer
is derived from the Greek root poly-, meaning many, and mer, meaning part or
segment. Many of the same units (or mers) are connected together to form a long
chain or polymer.

Polymers
are of two types: Polymers such as starch, proteins and DNA occur in Nature,
and are called Natural polymers. Synthetic polymers are derived from petroleum
oil and made by scientists and engineers. Examples of synthetic polymers
include nylon and plastic.

Long
repeating chains can be linked together to form a cross-linked polymer, which
may become branched and become a Branched chain polymer. As the degree of cross
linking in the polymer increases, the polymer usually increases in rigidity and
toughness. This is why we see plastics that have different degrees of hardness
from a plastic bag to a hard-plastic baseball bat.