Chemistry Alive: Review of Basic Concepts

• It is soooooooo important that you understand so please ask questions.

• I will post this slides to my Brookwood teacher page today.– www.brookwoodhighschool.net/tlu.php?type=F

• Select Crawford from drop down and go to handouts

Concepts of Matter

• Anything that occupies space and has mass• Mass remains constant but weight varies

with gravity• Matter can be seen, smelled and/or felt • Solid, liquid or gas• Matter can be changed physically or chemically• Liquids conform to the shape of the container• Gas- no definite shape nor definite volume

Composition of Matter

• Matter is composed of substances called elements

• Elements cannot be broken down into simpler substances by ordinary chemical methods

• 96 % of body weight is made up of 4 elements

Carbon, Oxygen, Hydrogen, Nitrogen

• Atoms are the building blocks of elements- identical particles

Elements and Atoms

• Pure substances like carbon, hydrogen and oxygen that are composed of only one type of atom are classified as elements.

• Element is designated by a one- or two- letter chemical shorthand called the atomic symbol, C is for Carbon, Na is for sodium

• Atom is derived from the Greek word meaning “incapable of being divided”

• If an atom is split into its sub particles it loses the unique properties of its element

Element Atomic

Symbol

% Role

Oxygen O

65 Component of organic and inorganic molecules. Oxidation of glucose

Carbon C 18.5 Primary element Of all organic molecules

Hydrogen H 9.5 Ionic form influences the pH of body fluids. Component of most organic molecules

Nitrogen N 3.2 Component of proteins and nucleic acids

Elements of LifeElements of Life

Element Atomic

Symbol

% Role

Calcium Ca

1.5 Salt in bones and teeth; ionic form required for muscle contraction, neural transmission and blood clotting

Phosphorus P 1.0 Salt, in combination with Ca in bone and teeth. Nucleic acids, proteins; forms part of ATP

Potassium K 0.4 Ionic form major intracellular cation (+) ;nerve impulses and muscle contraction

Sulfur S 0.3 Component of contractile proteins of muscle

Sodium Na 0.2 Major extra cellular cation; water balance, nerve impulses and muscle contraction

Element Atomic

Symbol

% Role

Chlorine Cl 0.2 Major extra cellular anion(-)

Magnesium

Mg 0.1 Bone; cofactor for enzyme activity

Iodine I 0.1 Needed to make functional thyroid hormones

Iron Fe 0.1 Component of functional hemoglobin molecule

Trace elements less than 0.1 %: Cr, Co, Cu, Fl, Mn, Mo, Se, Si, Sn, V, Zn; Many found as part of enzymes or required for enzyme activation

Molecular Substances

I. When two or more atoms are chemically bonded a molecule is formed.

II. Two atoms of the same element bond together an element is produced. I.e. O2, H2

III. Two or more different atoms form molecules of a compound, CH4

IV. Molecule is the smallest part of a compound that retains the features of that compound

Compounds• A compound is a substance made from two or more elements

which have reacted chemically with each other.

For example : The element sodium is a highly reactive metal and the element chlorine is a yellow-green poisonous gas (non-metal). When the two react together, they form a compound called sodium chloride. Sodium chloride is common salt, which you eat with food.

Chemical Bonds

• IonicIonic– Electron transferredElectron transferred

• CovalentCovalent– Electron sharedElectron shared

• Hydrogen (polar Hydrogen (polar covalent)covalent)– Electron shared Electron shared

unequallyunequally

Chemical Reactions

•When reactions take place, there is an exchange of energy.• Whenever chemical bonds are broken, energy is released. •When new bonds are formed, energy is stored. •Sometimes [when the energy stored in the new bonds of the products is less than the energy released from the reactants] energy is released during a reaction. This energy may be given off as heat, or it may be used to do work. •Sometimes, the products of the reaction store more energy in their chemical bonds than the reactants had stored. This stored energy can be held for later use.

reaction where reactants and products are balancedC6H12O6 + 6O2 6CO2 + 6H2O + ATP

Chemical Reactions

All chemical reactions involve atoms trying to getAll chemical reactions involve atoms trying to geta full outer shell of electrons. a full outer shell of electrons.

When an atom reacts with another atom, it will eitherWhen an atom reacts with another atom, it will either1. Lose electrons to form a stable positive ion.1. Lose electrons to form a stable positive ion.2. Gain electrons to form a stable negative ion. 2. Gain electrons to form a stable negative ion. 3. Share electrons to form a stable molecule.3. Share electrons to form a stable molecule.

Key to chemical reactivity is the rule of 8s. ( Octet Rule)

Synthesis reactionsSynthesis reactionsAs an example of a synthesis reaction : As an example of a synthesis reaction :

Ca + S -------------------> CaSCa + S -------------------> CaS

The + sign means "The + sign means "reacts withreacts with" or "" or "combines withcombines with" " and the arrow indicates "and the arrow indicates "to formto form".".

Synthesis Reactions: Summary

• Involve bond formationInvolve bond formation

• Energy-absorbing reactionsEnergy-absorbing reactions

• Underlie all anabolic (constructive) Underlie all anabolic (constructive) activities in body cellsactivities in body cells

• Growth and repair of worn-out or Growth and repair of worn-out or damaged tissuesdamaged tissues

Decomposition reactions

An example of a decomposition reaction is :

The products of this decomposition reaction have quite different chemical properties to the initial compound.

Decomposition Reactions• Bonds are brokenBonds are broken• Chemical energy is releasedChemical energy is released• Catabolic (destructive) processesCatabolic (destructive) processes• Molecule-degrading reactionsMolecule-degrading reactions• Digestion of food into building blocksDigestion of food into building blocks• Breakdown of glycogen to release glucoseBreakdown of glycogen to release glucose

Exchange Reactions

• Involves both synthesis Involves both synthesis and decomposition and decomposition reactionsreactions

• Bonds are both made and Bonds are both made and brokenbroken

• ATP reacts with glucose ATP reacts with glucose forming glucosephosphate forming glucosephosphate and ADPand ADP

• AB + C AC + BAB + C AC + B• AB + CD AD +CBAB + CD AD +CB

Chemical Reactions

• If a reaction releases energy it is exergonic• If a reaction absorbs energy it is endergonic

Catabolic and oxidative reactions are for the most part exergonic

4 Factors influencing chemical rxns

• Temperature: An increase in temperature increases the kinetic energy therefore the reactions are quicker

• Amount: As the concentration of reactants decline we reach chemical equilibrium

• Size: Smaller particles move faster, hence faster reactions

• Catalysts: increase a reaction without being used up, enzymes