An understanding of chemistry is fundamental to biology. Chemistry Basics An understanding of chemistry is fundamental to biology.

Elements All living and nonliving matter is made of elements that have chemically combined Elements are pure substances that can not be broken down by chemical reactions Examples of elements in biology are carbon, hydrogen, oxygen, nitrogen

Atoms Atoms are the smallest components of an element Atoms consists of a nucleus containing protons (+) and neutrons. The nucleus is surrounded by electrons (-) which are always in motion around the nucleus. Atoms join together to form compounds and molecules.

Chemical Bonds Electrons in the outer most energy level are the only ones involved in helping atoms to join together. Electrons can be shared between atoms by a covalent bond which forms a molecule. Electrons can be transferred between atoms creating an ionic bond and forming ionic compounds. Chemical bonding makes the atoms stable and conserves matter.

Mixtures and Solutions Mixtures and solutions are important in biological systems. Mixtures and solutions are not chemically combined so no chemical bonds have be formed between substances. In biology most mixtures and solutions contain water.

Water Water is a key component in living systems Water is a good solvent because the water molecule is polar.

Acids and Bases Acids and bases are formed when compounds are mixed with water to form solutions. Acid and base levels are important to the stability of living systems. Acids and bases are measured on the pH scale. Acids (1 strongest– 6 weakest), 7 = neutral, Bases (8 weakest – 14 strongest)

Diffusion Diffusion is when molecules move from areas of high concentration to areas of low concentration. Movement of molecules by diffusion is also very important to stability in living systems. Diffusion of molecules depends on: Temperature Pressure Concentration