Unit OneUnit One“Science Introduction and “Science Introduction and

Cellular Function”Cellular Function”

““The Chemistry of Life”The Chemistry of Life”

Basic ChemistryBasic Chemistry

Anything that has mass and takes up space is Anything that has mass and takes up space is MatterMatter

All matter (solid, liquid, gas, and plasma) is All matter (solid, liquid, gas, and plasma) is made of atoms, that may or may not be made of atoms, that may or may not be combined into molecules and compoundscombined into molecules and compounds

An Atom is defined as the smallest unit of An Atom is defined as the smallest unit of matter that still retains the properties of the matter that still retains the properties of the element to which the atom belongselement to which the atom belongs

Basic ChemistryBasic Chemistry An atom with one proton is an atom of the element An atom with one proton is an atom of the element

Hydrogen, and is given the shorthand designation of Hydrogen, and is given the shorthand designation of “H”“H”

An atom with two protons is an atom of the element An atom with two protons is an atom of the element Helium, and is given the shorthand designation of “He”Helium, and is given the shorthand designation of “He”

All atoms of all elements have a certain number of 3 All atoms of all elements have a certain number of 3 types of subatomic particles: types of subatomic particles: Protons, Neutrons, and Protons, Neutrons, and ElectronsElectrons

Protons and Neutrons are found in the central region of Protons and Neutrons are found in the central region of the atom, the the atom, the NucleusNucleus

Electrons are found orbiting around the nucleus in Electrons are found orbiting around the nucleus in somewhat specific “pathways”somewhat specific “pathways”

Basic ChemistryBasic Chemistry

Protons have a positive chargeProtons have a positive charge Neutrons have no chargeNeutrons have no charge Electrons have a negative chargeElectrons have a negative charge In an atom, the number of electrons equals In an atom, the number of electrons equals

number of protonsnumber of protons The number of protons in the nucleus is the The number of protons in the nucleus is the

Atomic NumberAtomic Number The number of protons and neutrons in the The number of protons and neutrons in the

nucleus of an atom is the nucleus of an atom is the Mass NumberMass Number

Basic ChemistryBasic Chemistry How an atom interacts with other atoms is determined How an atom interacts with other atoms is determined

by the electrons; therefore, the chemical behavior of the by the electrons; therefore, the chemical behavior of the atom is due to the actions of the electronsatom is due to the actions of the electrons

All atoms seek to be chemically stable by attempting to All atoms seek to be chemically stable by attempting to obtain 8 electrons in their outer shell called the obtain 8 electrons in their outer shell called the Valence ShellValence Shell

Those “pathways” mentioned earlier are areas in which Those “pathways” mentioned earlier are areas in which the electrons travel while orbiting the nucleus. The the electrons travel while orbiting the nucleus. The pathways are often referred to as pathways are often referred to as OrbitalsOrbitals

In order for an atom to achieve the desired chemical In order for an atom to achieve the desired chemical stability it will attempt to either gain or lose electrons stability it will attempt to either gain or lose electrons from the orbitals of the valence shellfrom the orbitals of the valence shell

HeliumHelium

CarbonCarbon

Basic ChemistryBasic Chemistry

The orbitals in which electrons are commonly The orbitals in which electrons are commonly found are the “S”, “P”, “D”, and “F” found are the “S”, “P”, “D”, and “F”

The S orbital can have up to 2 electronsThe S orbital can have up to 2 electrons The P orbital can have up to 6 electronsThe P orbital can have up to 6 electrons The D orbital can have up to 10 electronsThe D orbital can have up to 10 electrons The F orbital can have up to 14 electronsThe F orbital can have up to 14 electrons

IonsIons

Atoms in which the number of electrons does not Atoms in which the number of electrons does not equal the number of protons are equal the number of protons are IonsIons

If an atom has fewer electrons than protons it is If an atom has fewer electrons than protons it is positively charged (the + protons outnumber the – positively charged (the + protons outnumber the – electrons); these are called electrons); these are called CationsCations

If an atom has more electrons than protons it is If an atom has more electrons than protons it is negatively charged (the –electrons outnumber the negatively charged (the –electrons outnumber the + protons); these are called + protons); these are called AnionsAnions

He+ (cation), Cl- (anion) He+ (cation), Cl- (anion)

IsotopesIsotopes

Atoms of an element that have different Atoms of an element that have different numbers of neutrons are callednumbers of neutrons are called Isotopes Isotopes

Isotopes of an atom of a specific element have Isotopes of an atom of a specific element have the same atomic number (# of protons) but the same atomic number (# of protons) but different mass number (protons + neutrons)different mass number (protons + neutrons)

Radioactive Isotopes are used in medicine to Radioactive Isotopes are used in medicine to detect and treat cancer, and they are used to detect and treat cancer, and they are used to determine the approximate age of fossils determine the approximate age of fossils

MoleculesMolecules

A A MoleculeMolecule is a group of atoms held together is a group of atoms held together by the energy of interacting electronsby the energy of interacting electrons

There are 2 categories of bonds that electrons There are 2 categories of bonds that electrons form when interacting with each other:form when interacting with each other: Ionic Bonds – unequal sharing of e-Ionic Bonds – unequal sharing of e- Covalent Bonds – equal sharing of e-Covalent Bonds – equal sharing of e-

Because covalent bonds involve the sharing of Because covalent bonds involve the sharing of electrons, single, double, and triple bonds exist in order electrons, single, double, and triple bonds exist in order to optimize the presence of the electrons in an attempt to optimize the presence of the electrons in an attempt to fill the valence shell of each atomto fill the valence shell of each atom

MoleculesMolecules

The atoms of most inorganic (nonliving) The atoms of most inorganic (nonliving) substances form ionic bonds, whereas, the atoms substances form ionic bonds, whereas, the atoms of most organic (living) substances form covalent of most organic (living) substances form covalent bonds bonds

Examples of elements which are commonly found Examples of elements which are commonly found in organic substances are: Carbon, Hydrogen, in organic substances are: Carbon, Hydrogen, Oxygen, Nitrogen, and PhosphorusOxygen, Nitrogen, and Phosphorus

Examples of elements which are commonly found Examples of elements which are commonly found in inorganic substances are: Aluminum, Chlorine, in inorganic substances are: Aluminum, Chlorine, Lead, Silver, and GoldLead, Silver, and Gold

MoleculesMolecules

Hydrogen bonds are weak chemical bonds that Hydrogen bonds are weak chemical bonds that play a special role in biologyplay a special role in biology

Two key properties of hydrogen bonds cause Two key properties of hydrogen bonds cause them to play an important role in biological them to play an important role in biological molecules: they are weak, and as a result of molecules: they are weak, and as a result of their weakness, they are highly directionaltheir weakness, they are highly directional

The bottom line is that hydrogen bonds The bottom line is that hydrogen bonds stabilize the shapes of many important stabilize the shapes of many important biological moleculesbiological molecules

Water and Hydrogen BondsWater and Hydrogen Bonds

Due to the hydrogen bonds that hold a water Due to the hydrogen bonds that hold a water molecule together, water has some very unique molecule together, water has some very unique physical properties:physical properties: Heat Storage of Water – heats up slowly and holds its Heat Storage of Water – heats up slowly and holds its

temperature for longertemperature for longer Ice Formation – solid water (ice) is less dense than Ice Formation – solid water (ice) is less dense than

liquid waterliquid water Cohesion – allows water molecules to stick together Cohesion – allows water molecules to stick together

and form droplets “Surface Tension”and form droplets “Surface Tension” Adhesion – allows a water molecule to stick to another Adhesion – allows a water molecule to stick to another

polar molecule that is not waterpolar molecule that is not water

Water and Hydrogen BondsWater and Hydrogen Bonds

Polar molecules other than water are called Polar molecules other than water are called HydrophilicHydrophilic because they are attracted to the because they are attracted to the hydrogen bonds of waterhydrogen bonds of water

Nonpolar molecules are called Nonpolar molecules are called HydrophobicHydrophobic because they are repelled by the hydrogen because they are repelled by the hydrogen bonds of waterbonds of water

If polar molecules dissolve in water they are If polar molecules dissolve in water they are SolubleSoluble

Ionization of WaterIonization of Water

The Chemical Formula for water is HThe Chemical Formula for water is H22OO The Structural Formula for water is:The Structural Formula for water is:

Ionization of WaterIonization of Water

Water can be broken apart into two ions:Water can be broken apart into two ions: H+ and OH-H+ and OH- H+ is a Hydrogen CationH+ is a Hydrogen Cation OH- is a Hydroxide AnionOH- is a Hydroxide Anion H+ equals acidicH+ equals acidic OH- equals basicOH- equals basic The way to measure the acidity or basidity of a The way to measure the acidity or basidity of a

substance is by using the pH scalesubstance is by using the pH scale

pH Scale – “Percentage of pH Scale – “Percentage of Hydrogen”Hydrogen”

The scale ranges from 0 to 14The scale ranges from 0 to 14 O to 6.9 is acidic, with 1 and 2 being very acidicO to 6.9 is acidic, with 1 and 2 being very acidic 7 is neutral (neither acidic or basic)7 is neutral (neither acidic or basic) 7.1 to 14 is basic, with 13 and 14 being very basic7.1 to 14 is basic, with 13 and 14 being very basic Again, if there are many hydroxide anions (OH-) Again, if there are many hydroxide anions (OH-)

in solution, then the solution is basicin solution, then the solution is basic If there are many hydrogen cations (H+) in If there are many hydrogen cations (H+) in

solution, then the solution is acidicsolution, then the solution is acidic

pH ScalepH Scale

pH Scale and BufferspH Scale and Buffers

In order to change the pH of a solution, a buffer In order to change the pH of a solution, a buffer can be addedcan be added

A buffer is a solution of known pH that can lower A buffer is a solution of known pH that can lower or raise the pH of the solution in questionor raise the pH of the solution in question

Buffers do the above by either absorbing or Buffers do the above by either absorbing or releasing H+ cations into solutionreleasing H+ cations into solution

Buffers are important in that they keep solutions Buffers are important in that they keep solutions from becoming too acidic or too basic; buffers from becoming too acidic or too basic; buffers keep solutions’ pH in an acceptable range keep solutions’ pH in an acceptable range