Bio Unit 1 Notes Essay example

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Atomic Structure

* *

Orbits are set at a specific energy level
Electrons can change energy levels depending on whether they are releasing energy or absorbing energy
A release in energy would drop the energy level
A absorption would increase the energy level

Chemical Bonding

Chemical bonding is when an atom or a molecule is joined together with another atom or molecule. They are joined via sharing of electrons.

There are two main types of chemical bonding intra and inter.

Intra Molecular Bonds
An Intra molecular bond is a bond between atoms.
Characteristics of intra molecular bonds:
Forms molecules
Very strong

Types of Intra Molecular Bonds

There are two types of intra molecular bonds ionic and covalent.

Ionic bonds
Ionic bonds involve the giving away of an electron. Ionic bonds are generally weaker and tend to dissociate in H2O

Covalent bonds
Covalent bonds involve the sharing of electrons. They are generally stronger then ionic bonds.

Electronegativity involves an atoms affinity (how much they like) their electrons.
Oxygen has a high electronegativity meaning that it is unlikely to give up its atom, thus sharing occurs when O is involved.
Sodium (Na) has a low electronegativity thus it is likely to give up its atom.
When two atoms have the same electronegativity haring will be equal.
Non-polar covalent bonds occur when electrons share equally
When two atoms have different electronegativity’s 1.7
An ionic bond is formed.

Intermolecular Bonds
An intermolecular bond occurs between two molecules. They are generally weaker than intra molecular bonds.

Types of Intermolecular Bonds

There are two types of intermolecular bonds London Dispersion Forces and Dipole-Dipole Forces.

London Dispersion Forces
The movement of electrons changing the charge.


Dipole-dipole forces are attractive forces between the positive end of one polar molecule and the negative end of another polar molecule

The result of polar molecules, they are the strongest intermolecular force. The strongest dipole bond is he Hydrogen bond; it forms between H+ and molecules such as Oxygen or Nitrogen.
***Interactions between molecules will give the molecule its characteristics thus determining the function of the molecule. ***

Molecular Polarity

Molecular polarity is the polarity of the entire molecule.

Factors determining Molecular Polarity

Factors that determine a molecules polarity include Bond Polarity and the Symmetry of the Molecule.

Bond Polarity

The types of bonds found within the molecule itself determine Bond polarity. * * Symmetry of Molecule

Overall bonds and shape of molecule determines polarity
For example the molecule CH4 should be polar if you take into consideration the individual bonds, but due to the molecular shape of CH4, the electrons are evenly distributed, resulting in a non-polar molecule.

Common Biochemical Reactions

There are four biochemical reactions:

Redox Reaction


Also known as dehydration synthesis or condensation.
It happens when two molecules are combined and water is produces as a byproduct *

The four biological matters are made in this manner.


The opposite of Dehydration. It occurs when a molecule is broken up via the addition of water.

Neutralization Reaction

When an acid and a base are combined to form a salt and water.

Redox Reaction

The transfer of an electron from one molecule to another
Also known as a reduction oxidation reaction

The gain of an electron
The loss of an electron.

In most cases a H+ atom accompanies the electron in the transfer.


* Characteristics of Water
Water is a universal solvent
More substance dissolve in water than any other solvent; disrupts charges in other molecule
Strong Adhesion:…