Chapter 2: Chemistry Comes Alive

How many elements are recognized?

118 elements. 92 occur in nature.

Periodic table

A listing of the known elements and helps to explain the properties of each element.

Matter

Anything that occupies space and has mass.

Protons

Bear a positive electrical charge.

What four elements make up about 96% of body weight?

Carbon, oxygen, hydrogen, and nitrogen.

What form of energy is found in the food we eat?

Chemical energy

Describe the major energy forms.

Chemical energy, Electrical energy, Mechanical energy, Radiant energy or electromagnetic radiation.

Atoms

Each element is composed of essentially identical particles of building blocks.

What form of energy is used to transmit messages from one part of the body to another?

Electrical energy is the energy used by nerve cells to transmit messages to the body.

Mechanical energy

Energy directly involved in moving matter.

Kinetic energy

Energy in action.

Radiant energy or electromagnetic radiation

Energy that travels in waves.

Differentiate between matter and energy and between potential energy and kinetic energy.

Matter is anything that occupies space and has mass. Energy is defined as the capacity to do work, or to put matter into motion. Kinetic energy is energy in action. Potential energy is stored energy.

Neutrons

Neutral

What type of energy is available when we are still? When we are exercising?

Potential energy is available when we are still. When we exercise, PE is converted to kinetic (working) energy, specifically to mechanical energy.

Atomic mass unit

Protons and neutrons are heavy particles and have approximately the same mass

Electrical energy

Results from the movement of charged particles.

Potential energy

Stored energy, that is inactive energy that has the potential, or capability, to do work but is not presently doing so.

Energy

The capacity to do work, or to put matter into motion.

Nucleus

The center of the atom containing protons and neutrons tightly bound together.

Chemical energy

The form stored in the bonds of chemical substances.

Elements

Unique substances that cannot be broken down into simpler substances by ordinary chemical methods.

Atomic symbol

We designate each element by a one-or two letter chemical shorthand, usually the first letter of the element's name.