Unit 2: Basic Chemistry

Chemistry, as a science, boils down to two basic concepts……

Matter & Energy

Matter:• Anything that takes up space

and has massMass is a measurement

of matterWeight is the pull of

gravity on an object

Three (4) States of Matter• Solid – defined volume

and shape• Liquid – defined volume

with no definite

shape• Gas – no definite volume

or shape• Plasma - no definite

volume or shape;

only exist at

extremely high

temps (sun)

Energy:• The ability to do work; the ability to

put matter into motion.

• Forms of Energy include:• Light, heat, chemical, electrical,

mechanical

Energy Conversions

• In biology, organisms typically convert energy from one form into another.

• This is metabolism !!!!

Metabolism 1.) the sum total of the chemical processes that occur in living organisms, resulting in growth, production of energy, elimination of waste material, etc. 2.) the sum total of the chemical processes affecting a particular substance in the body

1. Plants convert light energy to chemical energy (photosynthesis)

Light Energy

Chemical Energy

2. Animals convert chemical energy (food)

into heat and mechanical energy

Chemical Energy

Mechanical Energy

Where does the energy all come from ?• The sun is the ultimate

source of energy.

• Plants directly utilize the energy from the sun and then pass stored energy from one organism to the next through eating relationships (Food Chain)

Types of Energy

• Potential: Stored energy; not being used at

the time.

• Kinetic Energy: Energy being used or

released (energy of motion)

So what is Chemistry and why do we study it in Biology ?

• It’s a study of the relationship between matter and energy.

• Life doesn’t exist without chemistry.

Living things are nothing more than extremely well organized, highly complex, precisely arranged atoms.

AtomsAtoms• The smallest, most

basic unit of matter

• Too small to be seen; many theory-based models have been developed to show their structure and properties

The Basic Atom

Proton +nucleus 1.0073 AMU

Neutron No Charge nucleus 1.0087 AMU

Electron -

Moving around in orbitals, clouds, or

shells

.00055 AMU; not usually

considered in the mass of an atom

Elements

Elements: are pure substances which could not be chemically broken down into simpler kinds of matter.

• More than 100 exist• Only 30 are important to living things

The Periodic Table

• All the elements are arranged on a chart known as the periodic table

Each Element Box

• Atomic Number = # of Protons (this is what makes one element different from another)

• Atomic Mass = Protons + Neutrons (Atomic Weight, Mass Number)

• Symbol: One or two letter abbreviation • Grammar: 1st Letter Capitalized; 2nd letter lowercase if present• Symbols based in Latin

So, in stable, neutral atoms…

• The # of protons = The # of electrons(The positive particles = The negative particles)

The # of protons = the atomic number

The # of electrons = the # of protons

The # of neutrons = Mass # - # of Protons

Let’s see if we got this straight ……….

What is the:Atomic number? _____Amu? _____Number of protons? ____Number of electrons? ____Number of neutrons? ____

What is the:Atomic number? _____Amu? _____Number of protons? ____Number of electrons? ____Number of neutrons? ____

Ions are charged atoms due to a loss or gain of electrons

• Ions are not neutral atoms; they have totally different chemical properties than their stable atom counterpart.

Ions

Cation: a positively charged atom

Anion: a negatively charged atom

Cation:

Positively charged ion due to a loss of electrons.

For example…• A neutral sodium atom has 11 electron• A sodium ion (cation) only has 10 electrons• Therefore a sodium ion has a +1 Charge

(One more proton than electron)

Anion:Negatively charged ion due to a gain of electrons.For example ….

• A Chlorine atom has 17 electrons• A Chlorine (ion) anion has 18 electrons • Therefore a chlorine ion has a -1 Charge

• (One more electron than proton)

Isotopes• Different forms of the same atom due to an

unstable nucleus with extra neutrons.

• Therefore, isotopes usually have a greater atomic mass than normal stable atoms.

E.g. Carbon Isotopes• Carbon typically has a mass of 12 (6P + 6N)

• Carbon 14 is an isotope of Carbon that has a mass of 14 (6P + 8N)• C14 is used to date fossils

Radioisotopes

• Most isotopes are radioisotopes

• Over time, the extra neutrons are lost from the nucleus as a form of radiation over time.

• Others: Uranium & Plutonium are used in

nuclear energy

Biological Elements• Most elements DO NOT exist in their

“pure atomic elemental state”

• Most combine with other elements to form molecules & compounds.

Oxygen Calcium Sodium Iodine

Carbon Phosphorus Chlorine

Hydrogen Potassium Magnesium

Nitrogen Sulfur Iron

Oxygen - O• Required for cellular respiration – the breakdown

of glucose to produce energy

Carbon - C• Key element in all organic compounds (made by

living things)

• Influences the acidity of body fluids (pH)Hydrogen - H

pH = potential to attract hydrogen ions

Nitrogen - N• Key element in Proteins and DNA

Calcium - Ca• Responsible for strong skeletons and teeth

Iron - Fe• Found in hemoglobin (blood): carries oxygen

Phosphorus - P• Part of the high energy compound ATP

Potassium - K• Ions necessary for proper muscle contractions

Sulfur - S• Found in muscle proteins

Sodium - Na• Major extra-cellular cation (salt)

Chlorine - Cl• Major extra-cellular anion (salt)

Magnesium - Mg• Important for proper metabolic reactions

Iodine - I• Needed for proper thyroid functioning

GoiterGoiter

Compounds Most elements do not exist by themselves;

will combine with other elements.

Compounds are two or more different elements chemically combined

Properties of Compounds

• Compounds are much different than the elements that compose them

Sodium in water

But yet, Sodium Chloride = Salt

Molecules• Form from the Form from the covalent covalent bonding of bonding of

atoms (could be like atoms); or the atoms (could be like atoms); or the simplest part of a compoundsimplest part of a compound

• Examples:Examples:

Molecules – but not compounds

NaCl H2O

Chemical Formulas• Uses the symbols and the Uses the symbols and the

proportion of each atom proportion of each atom that makes up the that makes up the compoundcompound

• HH22O: Two hydrogen atoms O: Two hydrogen atoms and one oxygen atom and one oxygen atom combine to make watercombine to make water

Can you guess what compound has this chemical formula? C55H72O5N4Mg Chlorophyll

Coefficients• Used in front of formulas to indicate how Used in front of formulas to indicate how

many moleculesmany molecules• Example:Example: 2H2H22OO = 2 water molecules= 2 water molecules

Ions: Symbolized by raised charges• Examples: Examples:

NaNa++ = Sodium plus 1 ion= Sodium plus 1 ion

CaCa+2+2 = Calcium plus 2 ion = Calcium plus 2 ion

Physical Properties of Matter• Observable changes in matter that do not change

the chemical properties of the matter

Color, shape, phase, texture, size, etc..

Chemical Properties of Matter• Observable changes in matter that change the

chemical properties of the matter

New pieces of matter are created during a

chemical reaction – Usually non-reversible

by normal means

Chemical ReactionsChemical Reactions

Two of more substances called reactants characterized by a chemical change and yielding one or more products which are different from the reactants.

C6H12O6 + O2 CO2 + H2O

Reactants Products

Exothermic Reaction• Energy is given off from the chemical reaction (will see a

temperature increase)

Endothermic Reaction• Energy is absorbed from the chemical reaction (will

see a temperature decrease)

A common example is a chemical ice pack, which usually contains water and a packet of ammonium chloride

Chemical Bonding• Occurs when an atoms

chemical properties are not stable

• Most elements rarely exist by themselves

• The number and arrangement of electrons in an atom determines if it will combine to form compounds

Atomic Models

• 1st shell: full and stable with 2 electrons• 2nd shell: 8, 3rd shell : 8, 4th shell: 8• Octet Rule: Electron shells are stable with 8

electrons (except the 1st)

• Any element atom that does not meet the outer shell electron requirements will chemically bond with another atom

• Electrons in the outer shell are called valence electrons

Examples…

Oxygen: Carbon:

• 8 Protons• 8 Neutrons• 8 Electrons

• 2 in the 1st shell, 6 in the second shell (valence)

• 6 Protons• 6 Neutrons• 6 Electrons

• 2 in the 1st shell, 4 in the second shell (valence)

An easy way to figure valence shell electrons ….

Use Periodic Table: Columns are arranged to indicate similarities in chemical properties; The column number = the number of valence electrons

• All elements in column one = 1 valence electron• All elements in column two = 2 valence electrons• And so on…..• Column eight = inert gases (non-reactive)

1

2 3 4 5 6 7

8

How it works 1:

1st Shell Two electrons Two elements2nd Shell Eight electrons Eight elements3rd Shell Eight electrons Eight elements4th Shell Eighteen electrons Eighteen elements

• Periods are rows / represent shellsPeriods are rows / represent shells

• “Families” hint at basic chemical behavior

How it works 2:

Elements in this column Elements in this column GIVE / LOSE one GIVE / LOSE one electron electron

Elements in this column Elements in this column GIVE / LOSE two GIVE / LOSE two electrons electrons

Elements in this column Elements in this column have a FULL outer shell. have a FULL outer shell. They do They do NOTHING. (inert)NOTHING. (inert)

Elements in this column Elements in this column TAKE / GAIN one TAKE / GAIN one electron electron

Elements in this column Elements in this column TAKE / GAIN two TAKE / GAIN two electrons electrons

Elements in this column Elements in this column generally SHARE generally SHARE three electronsthree electrons

Elements in this column Elements in this column generally SHARE generally SHARE four electronsfour electrons

Elements in these columns Elements in these columns generally have little role generally have little role in living thingsin living things

1. Ionic Bonding• Occurs between positive and negative ions • Formed when one or more electrons are

transferred from one atom to another• Example: Salt - NaCl

Ionic Bonds

• Are relatively weak bonds• Do not contain much energy

2. Covalent Bonds• Form between atoms that will share one or

more pairs of electrons

• Example: Water – H2O

• Results in the formation of molecules• Strong bonds – contain much stored energy

Mixtures• A mixture is made when two or more substances are

combined, but they are not combined chemically.

General properties of a mixture: • The components of a mixture can be easily separated. • The components each keep their original properties • The proportion of the components is variable

Types of Mixtures • There are two main categories of mixtures: homogeneous

mixtures and heterogeneous mixtures. In a homogenous mixture all the substances are evenly distributed throughout the mixture (salt water, air, blood). In a heterogeneous mixture the substances are not evenly distributed (chocolate chip cookies, pizza, rocks)

1. Solutions• A mixture in which one or more

substances are uniformly distributed into another

• Can be solids, liquids, gases

• Solute: the substance dissolved• Solvent: The substance in which

the solute is dissolved

• Water = Universal Solvent

An example of a solution: Sugar in Water• Sugar = Solute• Water = Solvent

• Though the sugar dissolves in water, neither of the molecules are changed chemically

Solution Characteristics• Typically clear• Concentration = amount of solute dissolved into a fixed amount of solvent

• Saturated Solutions = No more solute can be dissolved

2. Suspension• Mixture in which

substances are typically larger, and do not readily dissolve.

• The substances will temporarily mix but, will settle out over time

• Are typically cloudy at first

3. Colloid

• In-between solution and suspensions

• Milk, Jell-O and Cytoplasm common examples

Definition: a homogeneous substance consisting of particles of one substance dispersed through a second substance. Colloids include gels, sols, and emulsions; the particles do not settle and cannot be separated out by ordinary filtering or centrifuging like those in a suspension.