biochemistry

• The world around us is made of chemicals.
• Matter is any thing that has mass and takes up space
• Chemistry is the science that deals with matter: the structure and properties of matter and the trans-formations from one form of matter to another
• chemical change, more commonly called a chemical reaction, substances are used up (disappear) and others are formed to take their places.
• Matter also undergoes other kinds of changes, called physical changes. These changes differ from chemical reactions in that the identities of the substances do not change
• Dissolving sugar in water is a physical change
• chemical properties of a substance, we mean the chemical reactions that it undergoes.
• Physical properties are all properties that do not involve chemical reactions. For example, density, color, melting point, and physical state (liquid, solid, gas) are all physical properties.
• Scientists learn by using a tool called the scientific method
• the great philosopher Aristotle (384–322 BCE) believed that if you took the gold out of a mine it would grow back. He believed this idea because it fitted in with a more general picture that he had about the workings of nature
• fact is a statement based on direct experience. It is a consistent and reproducible observation.
• hypothesis is a statement that is proposed, without actual proof, to explain the facts and their relationship.
• A theory is the formulation of an apparent relationship among certain observed phenomena, which has been verified to some extent. In this sense, a theory is the same as a hypothesis except that we have a stronger belief in it because more evidence supports

  it.
• One of the most important ways to test a hypothesis is by a controlled experiment.
• The scientific method is thus very simple. We don’t accept a hypothesis or a theory just because it sounds right. We devise tests, and only if the hypothesis or theory passes the tests do we accept it.
• Hypotheses and theories call the attention

  of scientists to discover new facts.
• many scientific discoveries result from serendipity,

  or chance observation