Characteristics of Life, Cell Theory, and Atomic Structure
Three major characteristics of life
1.Energy 2.Cells 3.Information
4.Replication 5.Evolution
The cell theory
All organisms are made of cells and come from pre-existing cells
Three major domains of life
Archaea, Bacteria-Prokaryotic microorganism, single-celled whose cells have no nucleus
Eukarya
Adaptation
A trait that increases the fitness of an individual in a particular environment
Genus-Made up of a closely related group of species
Species-made up of individuals who regularly breed together
Atoms are composed of
Protons-Positive
Neutrons-Neutral
Electrons-Negative
Atomic number-atoms with the same atomic number, have the same chemical properties, belong to the same element(Is on bottom and represents the number of protons)
Mass Number-
number of protons plus neutrons of the most common isotope(Is on top)Electrons move around orbitals, each orbital holds 2 electrons, orbitals are grouped into levels called electron shells, Electrons shells are numbered, the smaller the number the closer it is to the nucleus. each electrons shell contains a specific number of orbitals. electrons fill the inner shells first then the outer. outside shell has to have 8 electrons and is called valance shell
Atoms-Are most stable when each electron orbital is filled
Molecules-Are substances held together by covalent bonds
Covalent Bond-Each atoms unpaired valence electrons are shared by both nuclei to fill their orbitals.
Ionic Bond-Electrons are transferred from one atom to another
Electronegativity
An atom with a molecule with a high electronegativity, holds electrons more tightly, has a negative charge,the other atom will have a positive charge
NonPolar Covalent bond-Electrons are evenly shared,Bond is symmetrical
Polar covalent bond-Electrons are asymmetrically shared
Ion
An atom or molecule that carries a charge
Cation-Atom that loses an electron and becomes positive charged
Anion-Atom that gains electron and becomes negative charged
Ionic bond-
resulting in attraction between oppositely charged ions.Life is based on water because it is a GREAT SOLVENT, covalent bonds in water are polar because oxygen has a greater electronegativity than hydrogen. Oxygen has a negative charge, Hydrogen has a positive charge.
Water-is unique due to its structure, small size, Bent shape, highly polar covalent bonds, overall polarity
PH scale- The more hydrogen you have the more acidic and the less basic
Potential Energy-is stored energy. bonds contain this and release kinetic energy when bonds break