THE CHEMICAL BASIS OF LIFE CHAPTER 2 CHEMICAL

THE CHEMICAL BASIS OF LIFE CHAPTER 2

CHEMICAL BASIS OF LIFE Think about the levels of organization… Molecule, Cell, Tissue, Organ, etc. Chemistry is the science of matter and how it changes Body structure and functions result from chemical changes within celss

STRUCTURE OF MATTER Matter is anything that has weight and takes up space The simplest example of matter with specific chemical properties is called an element Elements are made up of atoms, which are the smallest complete units of matter

ATOMIC STRUCTURE Each atom has 2 parts: 1. Nucleus 2. Electron Cloud

ATOMIC STRUCTURE Within an atom’s nucleus are two particles: 1. Protons (positive charge) 2. Neutrons (neutral charge) Electrons (negative charge) are found in the electron cloud

ATOMIC STRUCTURE Because the nucleus has protons, it is positively charged The number of electrons equals the number of protons, canceling out the charges Atoms are always uncharged, or neutral

ATOMIC STRUCTURE The number of protons in an element is called the element’s atomic number The atomic weight (mass) is the total number of protons and neutrons in an atom

ISOTOPES Some atoms of the same element have different numbers of neutrons This gives them different masses, even though they are the same element These atoms are called isotopes Some isotopes may have unstable nuclei that decompose and release energy These are called radioactive isotopes