Matter Cycles/ Energy Flows Notes
 Everything you can see is made of two main things--matter (atoms) and energy.
 Atoms (matter) come in many different flavors—
hydrogen, oxygen, iron, sodium, calcium, etc.

Energy comes in many different forms—heat, light,
sound, motion, chemical, electrical, etc.

The type of energy that bonds one atom to another is
chemical energy. A desk is made of atoms bonded together
with chemical energy. Without the chemical energy the desk
would fall apart. People are made of atoms bonded together by
chemical energy. Without the chemical energy, we would fall
apart. Plants are made of atoms that are hooked together by
chemical energy. Plants convert sunlight into the chemical
energy used to bond atoms together. The food we eat is made of
atoms (matter) connected to each other by chemical energy.

When we eat food there are three main things that can
happen to the food.
a. Most of the food goes straight on through and comes out the
other end
b. Some of the food goes to our cells where it is taken apart and
reassembled to make human proteins for muscle, or skin, or
bone, or blood. The food is used to build, repair, or add onto
our bodies.)
c. Some of the food goes to our cells where the chemical energy in
the food is used to live—to walk, talk, think, etc. The energy in
the food eventually leaves our bodies as heat.
 Living things are made mostly of carbon (C), Hydrogen (H),
Oxygen (O), and Nitrogen (N). Of course we have many others
like iron and Calcium, and Sodium, but C, H, O, N are the four
major atoms that make up life.
 We get our CHON and the energy that connects them together
from our food. All our food comes from plants.
 Plants get their CHON from the air, water, and soil. The C and
O come from carbon dioxide (CO2) in the air which enters the
plants through tiny holes on the backs of the leaves. The plants
get the H they need from water (H2O). The plants get the N
from fertilizers in the soil. The plants hook the Cs, Hs, Os, and
Ns together using energy from the sun to make sugars. (Bark,
wood, stems, roots, and leaves are mostly made of sugars—but
most of the sugars we can’t digest.)
 When we eat food (C-H-O-N) there are three things that happen
to it (see above.) But what happens to the C H O N atoms when
our cells take out the chemical energy to live? We breathe out
the C and O as carbon dioxide. We get rid of the H and the N in
our urine.
 The carbon dioxide we breath out (CO2) can be used again by a
plant to make more food. The water (H2O) and nitrogen we get
rid of in our urine can be used again by a plant to make more
food. The atoms never get destroyed or disappear—they just
keep on getting re-used over and over again. That’s why we say
Matter Cycles!
 The energy in our bodies eventually leaves as heat. It doesn’t
go back to the sun and it’s not turned back into light. Energy
doesn’t get recycled forever and ever like atoms so we say
energy flows! Energy flows into plants as light, it’s trapped in
living things as chemical energy, and it eventually flows out
into space as heat.
Matter (atoms) cycle, but energy flows!
Name________________________________
1. Everything we can see is made of what two main parts?
2. What type of energy holds atoms together?
3. What are the three main things that can happen to food
we eat?
4. What are the four main atoms in living things?
5. Where do plants get their carbon atoms from to make
sugars?
6. Where do plants get their hydrogen atoms from to make
sugars?
7. Where do plants get the “glue” to connect the atoms
together to make sugars?
8. Where do animals get their atoms to build and repair
their bodies?
9. What happens to the carbon atoms in our food after the
energy has been used by the cell to live?
10.What happens to the hydrogen atoms in our food after
the energy has been used by the cell to live?
11.What eventually happens to the chemical energy in our
food after the cell has used the energy to live?
12.What is meant by the phrase: matter cycles, but energy
flows?