advanced biology unit 1 notes

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.