advanced biology unit 1 notes
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Basic Chemistry
Basic Chemistry Matter – anything that occupies space and
has mass Element – a substance that can’t be broken
down to other substances The body is made mainly of O (oxygen), C
(carbon), H (hydrogen), and N (nitrogen). It also consists of trace elements, which are
needed, but only in small quantities (Ca, calcium; P, phosphorous; K, potassium; and S, sulfur).
Control Minus Nitrogen
Goiter – minus Iodine
The AtomThe smallest unit of matter that still
retains the properties of an element.
Structure of the Atom Has 3 basic particles:
Proton – single unit of positive charge Electron –single unit of negative charge Neutron – no charge; neutral
Nucleus – atom’s central core which contains the protons and neutrons
Electrons orbit around the nucleus.
Periodic Table Using the periodic table, we can determine
what the actual structure of an atom of a certain element.
Atomic number – the number of protons in each atom of an element
Mass number – the sum of the number of protons and neutrons in an atom’s nucleus
Formula: Mass # - Atomic # = # Neutrons
Find the # of protons, neutrons, and electrons for each element.
Electron Arrangement Electrons determine how at atom will
behave. Electrons occur in energy levels,
sometimes called electron shells or orbitals. Depending on the atomic #, the atom can
have 1, 2, 3, or more shells. Electrons in the outer shell have the most
energy.
Electron Arrangement (con’t) Each shell can hold a certain # of electrons.
Formula: 2(n2) = # of electrons in the shell The # of electrons in the outer shell
determines the chemical properties of the atom.
Shells that aren’t completely full interact with other atoms.
Determine the # of protons, electrons, and neutrons for each. Then, draw the atom.
Ions An ion is an atom that has a positive or
negative charge due to the loss or gain of electrons.
Gain electrons = negative charge C-2 – carbon atom with 2 extra electrons
Lose electrons = positive charge C+2 – carbon atom with 2 less electrons
Types of Ions
Cations - have lost electrons (p+ > e-) giving them a positive charge.
Anions - have gained electrons (p+ < e-) giving them a negative charge.
Isotopes Isotopes have the same number of protons
and electrons, but a difference in the number of neutrons.
Radioactive isotopes have decaying nuclei, which give off particles and energy. They are used in biological research and medicine as tracers.
Chemical Bonding Chemical Bond – an attraction between 2
atoms, resulting from a sharing of outer-shell electrons OR the presence of opposite charges on the atoms.
Types of bonds: Ionic Covalent
Ionic Bonding Ions have a positive or negative charge. An ionic bond is the attraction between
oppositely charged ions.
Covalent Bond Forms when 2 atoms share one or more
pairs of outer-shell electrons. The number of covalent bonds at atom can
form is equal to the number of electrons needed to fill its outer shell.
Chemical Reaction A process leading to chemical changes in
matter; involves the making and/or breaking of chemical bonds.
Chemical reactions cannot create or destroy matter, but only rearrange it.
Reactant – starting material Product – ending material
2H2 + O2 2H2O
Water Made of 2 hydrogen
atoms and 1 oxygen atom joined by a covalent bond.
It is a polar molecule, having opposite charges on opposite ends.
This allows cohesion, which is the tendency of molecules to stick together via hydrogen bonds.
Solution A liquid consisting of a
homogeneous mixture of two or more substances.
Parts of a solution: Solvent – dissolving agent Solute – substance being
dissolved
Aqueous solution – water is the solvent
Acids and Bases Acid – chemical compound that donates H+
to solutions Ex. HCl
Base – chemical compound that donates OH- to solutions and accepts H+
Ex. NaOH
pH Scale Scale used to describe
the acidity or basicity of a solution Ranges from 0 – 14
0 – most acidic 7 – neutral 14 – most basic
Buffers
Substances that resist changes in pH by accepting H+ when there are too many, or
donating H+ when there is not enough.